Biology: For Csec®

Biology

for

CSEC®

Biology

for

CSEC®

Richard

Fosbery

Charmaine

Allison

Foster

Peart

3 Great

Clarendon

Oxford

It

University

furthers

and

Oxford

©

CXC

®

Council

The

rights

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UK

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8

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5

in

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(UK)

Ltd.,

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Acknowledgements

Cover

photograph:

Mark

Lyndersay,

Lyndersay

Digital,

Trinidad

www.lyndersaydigital.com

Illustrations

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the

Contents

Introduction

Section

5

5.8

Respiration

How

to

learn

1

6

5.9

Gas

How

to

learn

2

8

5.10

Breathing

78

5.11

Smoking

80

A:

Living

Organisms

in

74

exchange

surfaces

76

the Practice

exam

questions

82

Environment

Unit Unit

1

1.1

1.2

The

world

Ecology

1.4

Food

1.6

2

Food

you

The

6.1

Transport

6.2

Transport

6.3

The

6.4

Blood

6.5

Immunity

6.6

Xylem

6.7

Investigating

6.8

Phloem

and

energy

flow

exam

impact

The

2.3

Pollution

90

questions

of

humans

management

impact

on

and

Practice

of

and

human

recycling

What

will

of

Life

climate

the

future

activities

change

bring?

questions

Processes

3.2

Microbes

Cells

and

animal

7

Excretion

7.1

Excretion

7.2

The

7.3

Kidney

7.4

Movement

7.5

Joints,

human

urinary

system

104

functions

106

108

muscles

and

and

movement

110

exam

questions

112

36

8

Irritability

Disease

cells

8.1

Coordination

8.2

Plant

8.3

Invertebrate

8.4

Nerves

8.5

The

8.6

Eye

8.7

Drugs

8.8

The

and

survival

114

responses

Transport

bodies

across

exam

and

cell

membranes

questions

nutrition

4.3

Leaf

52

4.4

Investigating

4.5

Plant

Unit

photosynthesis

exam

Digestion

nutrition

questions

and

food

defects

Teeth

5.3

Enzymes

and

5.4

Factors

5.5

Absorption

5.6

Balanced

and

the

pupil

reflex

124

126

human

skin

exam

128

questions

130

Growth

guts

and

9.1

Growth

9.2

Sexual

9.3

The

9.4

Reproduction

9.5

Flowers

9.6

Pollination

reproduction

132

54 and

asexual

reproduction

134

56 menstrual

cycle

136

58

breathing

substances

9

and

birth

control

138

140

to

seed

dispersal

142

60 Practice

5.2

122

48

structure

mineral

120

eye

46

50

Testing

118

brain

44

Photosynthesis

Practice

responses

the

42

Nutrition

of

116

38

Types

exam

questions

144

62

64 Unit

5.7

102

34

4.2

5.1

movement

30

4.1

5

and

26

Practice

Unit

100

40

make

Practice

4

98

questions

Cells

Plant

Unit

storage

exam

32

exam

3.1

3.4

96

24

Unit

3.3

94

transpiration

22

Practice

3

transpiration

28

effects

Practice

Unit

92

and

20

Conservation

B:

88

environment

2.2

Section

86

heart

16

Unit

2.6

humans

18

together

Waste

2.5

in

14

2.1

The

84

10

webs

Living

the

2.4

Transport

12

chains

Practice

Unit

around

Sampling

1.3

1.5

6

Biodiversity

that

affect

and

diet

Malnutrition

enzymes

assimilation

10

Disease

10.1

Diseases

10.2

Mosquitoes

10.3

Sexually

66 146

68 148

70 transmitted

infections

(STIs)

150

72 Practice

exam

questions

152

3

Contents

Section

Unit

11

C:

Continuity

Genes

and

and

Variation

Unit

inheritance

11.1

DNA

154

11.2

Mitosis

156

11.3

Meiosis

–

the

11.4

Meiosis

and

process

158

variation

160

11.5

Genetics

162

11.6

Inheritance

164

11.7

Sex

Practice

exam

and

sex

questions

linkage

Variation

and

selection

12.1

Variation

170

12.2

Natural

selection

172

12.3

Species

and

12.4

Artificial

12.5

Genetic

technology

178

Practice

exam

180

Unit determination

12

13

How

their

formation

selection

to

take

176

questions

the

exam

166

13.1

Paper

1

13.2

Paper

2

13.3

Paper

182

168

Structured

data

analysis

questions

4

174

2

Section

184

B

–

essay

questions

186

Index

188

Acknowledgements

192

Introduction

This

Study

Guide

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A

2

Apparatus

habitat

is

a

place

where

an

organism

and

techniques

for

sampling

habitats

depend

nature

of

the

habitat

and

the

List

the

quadrat

is

a

frame

made

of

organisms

wire

or

in

the

area

students.

that

live

assumptions

be

made

wood

that

a

that

when

there. sampling

A

crabs

the

on must

the

of

by

lives.

3

3

would

recaptured

they

KEY

you

habitat.

recaptured

in

ways

(see

QUESTIONS

calculate

released adapted

non-

leaves.

later,

crabs, features

has

have

smaller

and

2 you

lilies

the

=

number

When

floating

their

time

marked

used

for

water

non-

1

an

a

water

SUMMARY the

in

Argentina.

wettable

predators

insects

high

leave

water

toxic

a

nocturnal.

estimates

use

tiny

insects.

Figure

To

using

collect

behind.

useful

smaller

traps

stronger

the

contents

cardboard

keep

are

rivers;

sieves

into

Pitfall

or

and

the

sorting;

•

these

ponds

to

an

forest

•

is

1.2.2).

encloses

a

and

b

with

when

a

quadrat,

using

the

mark–

2

known

area,

e.g.

1 m

.

It

is

used

to

estimate

species

density.

release–recapture

technique.

13

1.3

Ecology

LEARNING

At

the

end

should

be

A

habitat

is

a

of

this

able

topic

you

group

offspring.

define

the

ecology,

abiotic,

terms

environment,

ecosystem,

niche,

community

of

Within

biotic,

population,

and

the

community.

factors

by

species

is

list

some

biotic

•

major

abiotic

factors

different

the

on

that

can

species

habitat

breed

of

organisms.

there

together

are

to

A

species

produce

populations

of

fertile

each

species.

a

that

of

An

of

in

ecosystem

an

it

organisms

organisms

influence

species

Many

impact

The

the

with

their

live

in

comprises

organisms.

ecosystem

has

and

that

A

including

other

species

a

surroundings

particular

the

community

niche

its

is

the

trophic

(see

or

place

and

role

level

form

all

a

the

fulfilled

and

the

1.6).

and

factors

discuss

the

study

environment.

relationships •

many

organisms

to: Ecology

•

supports

OUTCOMES

abiotic

these

aspects

biotic

organisms.

of

the

influences

T able

factors

surroundings

into

(see

two

groups

T able

influence

of

organisms.

factors:

abiotic

We

can

factors

divide

and

1.3.1).

1.3.1

Abiotic

factors

Biotic

factors

Bulb

All

Sample

soil

or

of

the

non-living

ecosystem

that

organisms

in

features

influence

the

of

an

All

the

the

influences

organisms

community

have

on

in

the

each

that

community

other

leaf

Sieve

Latitude,

altitude,

climate,

Food,

water,

disease,

litter

temperature,

water,

oxygen

concentration,

carbon

concentration,

light

light

duration

predation,

dioxide

food,

intensity,

(hours

of

with

daylight),

competition

water

and

members

species

and

living

of

with

the

for

space

same

other

species

Funnel

rainfall,

water

Soil

The Figure

1.3.1

A

T ullgren

as

a

out

for

soil

provides

very

if

a

to

way

mass

cons tant

have

to

of

mass’

phrase

to

ion

soil

content

a

habitat

and

samples

This

in

the

for

leaf

many

trays

method

Another

litter

organisms.

or

on

from

You

to

surface

newspaper

depends

way

the

can

on

and

eyesight

sample

soil

for

of

sift

as

the

collect

soil.

through

many

animals

of

is

Spread

looking

the

to

animals

set

like

The

to

or

prefer

fall

shown

damp,

through

in

Figure

dark

the

1.3.1.

conditions

sieve

in

the

The

so

light

they

funnel

and

dries

move

are

out

away

the

up

soil;

a

from

collected

for

soil

the

study.

physical

features

of

soil

can

be

analysed

easily

in

the

laboratory:

describ e

de ter mine

soil

lamp,

that

use

dry

•

Water

Every

plan t

materi al .

content

day

difference

water

•

14

pH,

TIP

useful

you

soil

small.

animals

a

of

your

funnel

‘Dry

soil

mineral

habitat

animals.

are

is

depth,

funnel

samples

EXAM

soil

content,

T ake

the

between

a

sample

soil

the

of

sample

original

soil,

until

mass

weigh

the

it

mass

and

the

and

leave

stays

dried

the

it

to

same.

mass

gives

dry.

The

the

content.

Water

holding

it

a

into

–

weigh

flower

capacity

pot

or

–

T ake

fi lter

a

known

funnel

with

mass

fi lter

of

dry

paper

soil

at

and

the

place

bottom.

Pour

the

a

known

soil.

volume

•

of

water

and

it

crucible

into

a

mass

remains

Air

is

content

volume

into

the

from

soil

is

the

a

pH

from

–

by

T ake

a

T ake

crucible

open

so

top

known

that

of

a

measuring

through

is

the

to

a

cool

the

matter;

cylinder

and

mass

Bunsen

and

the

holding

of

dry

mineral

the

Place

Stir

weigh.

stays

The

capacity.

soil.

burner.

then

mass

onto

measure.

water

known

with

until

air

to

expected

fills

of

the

of

an

up

Tip

and

the

Keep

same.

matter

stir

volume

and

+

in

can

dig

soil

air

the

some

of

is

The

what

known

up.

a

in

up

the

beaker

of

Scrape

large

break

of

volume

add

it

into

to

volume

(water

soil

tin

then

the

and

The

new

empty

out

water

leave.

volume

sample

of

can.

volume

the

small

end

it

the

subtracting

the

–

a

soil

strongly

organic

the

soil

the

allow

soil)

the

the

weighing

the

Push

pieces

calculated

in

from

drains

1.3.2).

containing

and

heat

and

lost

–

that

matter

and

Allow

(Figure

water

remaining

cooling

that

of

water

mineral

frequently.

heating,

•

the

Organic

soil

•

volume

Collect

tin

water.

off

beaker

the

soil

sample

(water

is

+

can).

Shake

or

Figure

stir.

T ake

a

small

sample

of

the

water

and

put

it

on

a

tile.

Add

a

1.3.2

As

dry

soil

organic

indicator

such

as

universal

Salinity

–

This

is

heated

matter

is

the

burnt

off

indicator. leaving

•

is

pH

measured

with

a

conductivity

meter.

T ake

20 g

to

of

be

the

mineral

matter

weighed.

3

dry

soil

the

water.

higher

and

add

Put

the

distilled

100 cm

the

probe

reading

the

into

more

water.

the

salt

water

there

Shake

and

is

in

well

take

the

a

and

pour

reading.

off

The

SUMMARY

1 Important

components

of

the

air

in

the

soil

and

in

the

atmosphere

Explain

the

•

Oxygen

–

See

for

5.8

Carbon

there

required

details

dioxide

are

regions

–

for

of

the

required

soil

of

plant

roots

and

all

organisms.

of

the

following

pairs

terms:

respiration.

microscopic

of

respiration

differences

are: between

•

QUESTIONS

soil.

as

plants

where

a

raw

and

light

material

algae

reaches

that

for

live

them.

a

abiotic

and

b

habitat

c

population

biotic

photosynthesis;

in

See

the

4.2

and

niche

upper

for

details

and

of community

photosynthesis.

•

Nitrogen

the

–

an

nitrogen

inert

to

gas,

make

but

into

some

microorganisms

organic

forms,

such

as

are

able

amino

to

d

species

a

Discuss

acids

2

abiotic T wo

other

important

abiotic

factors

that

influence

the

distribution

of

organisms

are

as

of

energy

green

a

source

organisms,

the

rate

There

at

are

such

which

many

distribution

and

light

as

and

for

algae

and

chemical

aspects

of

and

and

plants

some

of

of

temperature.

and

other

bacteria.

reactions

both

behaviour

wavelength,

light

occur

these

maximum

in

for

and

is

the

bodies

that

b

minimum

light

the

c

duration

for

of

animals

in

the

soil.

temperatures.

live

Write

a

these

the

the

abiotic

influence

in

factors

plants

that

soil.

factors

plants

that

ponds.

set

of

practical

POINTS instructions

soil 1

Ecology

2

Biotic

is

and

the

Abiotic

biotic

each

study

abiotic

abundance

3

importance

how

in

Discuss

that

3 KEY

Explain

grow

organisms.

influence

example

live

influence

influences

of

the

factors

needed

photosynthetic

T emperature

factors

organisms,

Light

population

and that

abundance

and

use

of

factors

factors

other.

of

living

factors

organisms

are

are

all

all

the

the

organisms

affect

in

the

in

their

distribution

for

the

for

an

analysis

following

of

features:

environment.

a

water

b

air

c

organic

content

d

water

and

ecosystems.

non-living

influences

features

that

of

an

organisms

holding

capacity.

ecosystem;

have

on

You

could

diagrams

use

(see

flow

page

chart

8).

15

1.4

Food

chains

energy

Food LEARNING

the

end

chains

of

this

topic

food

chain

be

able

define

the

terms

the

the

feeding

relationships

between

some

of

the

ecosystem.

food

chain

food

and

in

Figure

energy

1.4.1,

flows.

the

arrows

Arrows

show

always

the

point

direction

away

from

in

the

omnivore, food

food

an

herbivore, which

carnivore,

in

to:

In •

shows

you organisms

should

flow

OUTCOMES

A At

and

chain,

producer

and

towards

the

organism

doing

the

feeding.

In

this

food

chain

and the

grasshopper

is

a

herbivore

and

the

lizard

and

the

broad-winged

consumer hawk

•

draw

a

plant,

and

•

food

chain

herbivore,

with

are

carnivores.

a

carnivore

omnivore

draw

pyramids

of

numbers,

Grass

biomass

and

Long-horned

Lizard

Broad-winged

energy. grasshopper

Figure

Many

1

Tertiary

Primary

different

are

at pyramid

of

two,

fruits

and

at

are

seeds)

four

trophic

levels

omnivores

and

as

they

feed

on

animals.

feeding

levels

in

a

animals

food

are

chain

are

called

consumers.

trophic

Herbivores

levels.

are

or

and

more,

carnivores

trophic

are

levels.

secondary

If

you

eat

consumers.

primary

fish,

then

it

is

Omnivores

likely

that

feed

you

are

numbers

eating

hawk,

YOU

mockingbirds,

the

producers,

consumers

DID

organisms

Producers

1 500 000

A

as

with

consumers

Plants

1.4.2

such

(especially

chain

consumers

The

Figure

food

consumers

Secondary

200 000

A

birds,

plants

90 000

1.4.1

hawk

animals

that

that

feeds

at

are

carnivores.

the

top

of

a

An

food

animal,

chain

is

such

a

as

the

tertiary

broad-winged

consumer

KNOW?

Pyramids

In

some

communities

most

of After

the

plants

which

but

are

large

pyramid

small

are

trees

small

in

of

in

bulk.

and

estimating

the

data

can

This

numbers

gives

a

The

actual

of

organisms

at

each

trophic

level,

very

many

be

used

to

draw

pyramids

of

numbers

(Figure

1.4.2).

with

a

shape

of

communities

a

pyramid

there

are

of

numbers

many

depends

producers

with

on

far

the

community .

fewer

In

consumers.

base. are

Organisms

•

Habitats

left

to

samples

habitat

Algae

growing

seaweeds

and

on

the

levels.

A

pyramid

of

biomass.

per

are

metre

in

g m

(grams

squared).

higher

cannot

up

support

is

the

and

The

trophic

support

a

food

large

multiplying

data

is

the

levels

large

chain

tend

to

be

numbers

of

large

it

is

lost,

so

larger.

there

organisms.

is

not

As

much

energy

carnivores.

quantity

estimates

this:

of

biological

up

by

biomass

presented

in

the

of

a

material.

estimated

the

Weighing

numbers

organisms

pyramid

of

at

representative

present

different

biomass

in

a

trophic

(Figure

1.4.3).

of

the

biomass

in

trees

and

animals

is

not

available

to

the

next

The

–2

figures

at

for

rocks

Much 1.4.3

reasons

flows

Biomass

3987

two

•

energy

16

populations

number

There

Figure

the

shrubs

trophic

one

level.

trophic

As

a

level

result,

to

the

biologists

next

and

estimate

this

is

the

shown

energy

in

a

that

flows

pyramid

of

from

energy

At

the

top

of

the

pyramid

there

is

too

little

energy

to

support

another KEY

trophic

level

(Figure

POINTS

1.4.4).

1

Herbivores

carnivores

eat

eat

omnivores

plant

matter;

animals;

eat

plants

and

animals.

67

2

Predatory

fish

Tertiary

consumers

Food

chains

feeding

organisms.

Producers

are

consumers

Tadpoles

14 000

Primary

consumers

that

the

relationships

between

1600

show

feed

as

carnivores

green

are

plants;

animals

herbivores,

or

omnivores.

Water 87 000

Producers

weeds

3

The

arrows

show –2

Figure

1.4.4

A

pyramid

of

energy.

The

figures

are

in

kJ m

the

per

(kilojoules

per

of

energy

to

Pyramids

by

plants

through

is

a

habitat

shows

that

much

of

the

of

numbers,

lost

as

a

result

of

respiration

and

heat

environment

(Figure

1.4.5).

Much

is

also

lost

in

dead

loss

leaves

waste

(faeces

and

urine)

to

about

give

the

trophic

to in

an

ecosystem.

and

5 animal

energy

energy

levels

the

from

consumers.

and

information

absorbed

chain

energy

year).

biomass

flow

food

of

metre

4

The

a

–1

y

producers squared

in

flow

Energy

is

lost

from

each

decomposers.

trophic

level

of

as

heat

in

a

movement

the

result

and

form

of

respiration,

Released

or in

in

food

material

that

respiration

is

egested

and

metabolic

Tertiary

wastes

that

are

excreted.

consumers Dead

remains,

Released faeces, in

etc.

6

respiration

About

10%

entering Secondary

the

energy

consumer

trophic

Production

level

Dead

Released

remains,

faeces,

etc.

respiration

Primary

sresopmoceD

consumers

in

a

of

of

is

available

for

the

next

heat

trophic

level.

SUMMARY

QUESTIONS

consumers Dead

remains,

faeces,

etc.

1

Released

in

respiration

Draw

a

food

following

beetles

Producers

chain

using

information:

feed

on

bananaquits

small

orange

eat

small

the

leaves;

beetles.

Dead

remains,

2

Use

the

food

chain

you

etc. Energy

have

input

drawn

following:

primary

to

identify

producer,

consumer,

the

herbivore,

carnivore,

Sun

secondary

3 Figure

1.4.5

Energy

trophic

flow

level

in

is

a

habitat;

available

about

for

the

10%

next.

of

the

energy

that

enters

consumer.

Bananaquits

also

feed

a

on

oranges.

food

extra

chain

Redraw

to

show

information.

bananaquits

your

this

Why

described

are

as

omnivores?

17

1.5

Food

A LEARNING

terrestrial

the

end

of

this

topic

be

able

1.5.1

that

define

the

•

construct

term

a

shows

there

a

are

food

many

web

more

for

a

terrestrial

feeding

food

•

Food

than

webs

shown

in

food

food

chains.

web

web

from Barn

given

habitat.

relationships

to: simple

•

web

you show

should

food

OUTCOMES

Figure At

webs

owl

information

describe

predator–prey Antilles

racer

(snake)

relationships

•

explain

the

numbers

changes

of

in

predators

and Mangrove

cuckoo

prey Dominican

•

outline

the

use

of

the

role

anole

(lizard)

biological

control Caterpillars

•

explain

of

Common

decomposers.

Grass

Figure

1.5.1

This

food

web

organisms

If

Figure

1.5.2

Anolis

lizards

important

webs

in

are

part

the

of

an

you

are

given

area,

then

plant

may

most

habitats,

many

on,

so

prey

each

species

predator

to

their

numbers

do

eaten

have

animal

a

about

food

of

the

feeding

relationships

between

Dominica.

the

web.

feeding

relationships

Remember

that

each

in

an

type

of

by

different

more

than

species

one

of

herbivore,

predator

and

each

species

omnivores

eat

of

both

species.

Relationships

food

and

fall

in

such

a

•

web

on

Quantity

as

YOU

between

predators

and

their

prey

shows

at

least

that

two

the

success

biotic

of

a

herbivore

in

its

habitat

factors:

regular

plants

of

plant

decrease

there

is

not

food

then

the

enough

available

herbivore

food

and

–

If

the

number

population

some

animals

will

and

biomass

probably

may

die

of

of

decrease

starvation.

KNOW? •

Number

– mongoose

is

thought

to

If

for

the

there

extinction

Caribbean

birds

effect

night

the

Antiguan

owl.

many

and

the

predators

and

prey

they

species

have

that

few

prey

they

feed

species

on

then

of

the

greater

predators

than

if

there

on

any

were

one

few

species

predators

of

herbivore

with

many

will

be

different

including

prey Jamaican

predators

of

much

the

of

are

be

the responsible

hawk

species

for

them

to

eat.

and

The

has

18

draw

in

trees

not

pattern.

several

be

may

and

depends

The

information

can

some

forest

Forest

feed The

DID

shows

a

Fruits,

FOCUS

has

rise

you

in

Leaves,

Caribbean.

plant

In

bat

food

herbivore

STUDY

fruit

Bush-crickets

relationship

been

between

studied

in

the

different

numbers

habitats.

of

predators

Figure

1.5.3

and

prey

shows

species

the

changes

that

in

numbers

predator

only

of

a

prey

feeds

on

species

one

prey

that

has

only

one

predator

and

species.

Prey

As

the

the

predator

offspring

they

lack

eat

of

food

reproduce,

The

for

number

to

of

as

prey

so

species

its

the

prey

do

As

species

predators

predators

gain

the

so

means

not

increases,

numbers

reproduce.

many

of

the

species

survive

more

of

also

numbers

that

decreases

increase

number

fewer

enough

and

there

of

of

is

prey

the

and

cycle

food

because

predators

more

increases,

decrease.

offspring

food

more

survive

starve

starts

to

srebmuN

for

population

The

to

death.

Predator

again.

Time

Figure

Biological

1.5.3

A

predator–prey

control relationship

Predators

control.

to

the

the

from

sugar

introduced

such

used

the

India

cane

to

Caribbean.

leaves

cause

are

disease

species

the

larvae

Alternative

in

(Figure

of

pest

Indian

to

They

the

so

pests

of

of

methods

was

of

armyworms

rats

that

fed

of

as

on

and

control

wasps

they

eat

that

to

lay

were

with

in

many

too.

the

large

quantities

beans

and

maize.

resistant

release

their

to

much

species

become

are

as

crops

soya

harmful

introduced

prey

moths

onions,

caterpillars

pest

that

other

biological

be

eating

However,

vegetable

the

may

were

successful

callaloo,

ineffective

called

mongoose

many

(caterpillars)

is

that

Caribbean.

mongoose

this

pesticides

control

were

of

crops

species,

chemical

small

1872

serious

often

control

parts

destroying

Pesticides

them.

The

The

crop.

other

are

to

use

in

introductions,

Armyworms

of

be

avoids

environment.

Jamaica

of

can

It

to

viruses

eggs

that

inside

pest

1.5.3).

Figure

1.5.4

A

highly

control

Decomposers

its

Decomposers

matter.

are

Bacteria

microorganisms

and

fungi

are

that

feed

decomposers

on

dead

that

and

secrete

decaying

enzymes

eggs

dead

material

material

releasing

therefore

playing

and

digest

much

an

of

it

it.

They

into

important

the

role

break

down

atmosphere

in

the

huge

as

recycling

quantities

carbon

of

the

eat

hatch

the

caterpillar

inside

out.

carbon.

POINTS

QUESTIONS A

food

web

between Define

the

eggs

the

lays

caterpillars.

dioxide,

1

1

inside

larvae

biological

wasp

of

KEY

SUMMARY

this

When

from

onto

effective

–

the

terms

food

web,

biological

control

and

shows

food

the

chains

links

in

a

decomposer community.

2

Use

this

information

The

algae

to

draw

a

food

web

for

a

pond. 2

weeds

that

are

eaten

overhanging

Dead

and

leaves

water

primary

grow

by

trees

and

lice.

in

water

small

are

and

decomposers

Small

the

crustaceans;

decomposed

Dragonfly

consumers.

on

are

larvae

fish

by

dead

feed

by

diving

on

of

water

leaves

bacteria

eaten

and

leaves

water

on

fungi.

a

boatmen

beetles

algae,

prey

from

and

small

feed

on

water

boatmen.

Herons

feed

on

fish

and

each

a

Sketch

prey

b

a

graph

over

Explain

to

show

the

fluctuations

increase

Predators

you

have

drawn

in

predator

part

and

means

Explain

agent

why

is

careful

released

to

research

control

is

a

needed

pest

before

species.

a

An

increase

often

leads

numbers

of

in

to

its

and

parasites

of

are

used

of

biological

than

using

as

a

control

pesticides.

a 4

4

in

species

rather

changes

other.

species

and

dependent

larvae.

time.

the

are

crustaceans

dragonfly

of

predator

predator.

pest

3

of

species

prey

an

the

3 and

Numbers

new

biological

Decomposers

and

fungi

and

decaying

are

that

bacteria

feed

on

dead

matter.

19

1.6

Living

Eat LEARNING

and

the

end

of

this

topic

chains

and

be

able

define

the

symbiosis,

following

give

examples

species.

closeness

terms:

and

of

mutualism

each

are

show

not

the

the

feeding

only

relationships

relationships

that

within

exist

and

Many

with

species

different

‘live

together’

degrees

of

harm

with

or

different

benefit

to

degrees

each

of

other .

Symbiosis

of The

these

webs

these

parasitism,

commensalism

•

But

to: between

•

food

you communities.

should

eaten

OUTCOMES

Food At

be

together

term

symbiosis

means

any

form

of

close

relationship

between

relationships. two

that

are

species.

there

is

covered

plants,

In

many

little

in

such

not

as

harm

light

plants,

known

These

the

forests

reaching

bromeliads

photosynthesis.

do

tropical

trees;

as

and

plants

they

the

just

canopy

forest

floor.

epiphytes

air

do

the

plants,

not

use

take

of

Many

(Figure

gain

as

of

a

is

from

place

to

so

the

1.6.1).

sufficient

anything

them

leaves

dense

trees

These

light

the

for

their

trees

and

grow.

Commensalism

Commensalism

from

the

Egrets

feed

are

on

move

is

a

form

relationship

white

the

birds

insects

about

but

that

that

(Figure

of

the

symbiosis

other,

have

are

a

in

which

usually

close

disturbed

the

one

relationship

from

species

larger,

the

is

with

ground

benefits

unaffected.

cattle.

as

the

They

cattle

1.6.2).

Parasitism

Parasitism

Figure

1.6.1

This

coconut

covered

in

tree

is

gains

at

Animals

gain

by

herbivores,

a

good

living

such

is

chances

nutrition

the

and

in

that

stems

absorb

species

internal

inside

dodder

other,

where

the

one

host.

organism,

Lice

and

the

ticks

is

mammal

parasites,

gut

and

reproduction

the

a

and

water ,

the

of

larvae

plant

uses

from

that

some

ions,

to

as

(Figure

external

of

them

other

and

1.6.3).

tapeworms.

food.

millions

penetrate

sugars

bird

digested

produce

parasitises

suckers

mineral

such

absorb

to

and

of

will

plants.

the

other

These

Much

eggs

invade

to

Dodder

host’s

of

hosts.

twines

transport

molecules

the

maximise

new

tissues

(Figure

1.6.4).

large

1.6.3

A

human

body

louse

Figure

1.6.4

Yellow

dodder,

hippos. parasitic

20

parasite,

are

cattle, Figure

buffalo

of

of

source

with

as

have

used

to

food

also

energy

around

of

form

many

live

Y ellow

Egrets

of

parasites

the

1.6.2

a

expense

epiphytes.

parasites

Figure

is

the

plant

a

Mutualism

Not

all

many

which

have

relationships

examples

both

This

sexually.

reward

that

ensures

The

the

many

monkeys

and

the

more

trees

about

Legumes

fruits.

The

are

roots

with

tropical

this

is

participants.

in

such

pollinated

is

a

edible

disperse

as

can

competition.

that

See

plants

are

and

9.5

and

reproduce

(Figure

seeds

are

in

birds

solution,

food

fruits

Many

insects,

sugary

the

There

relationships

and

energy-rich

produce

avoid

the

mutualism.

which

of

animals

to

called

nectar,

trees

of

existing

animals,

are

supply

These

one

by

plants

a

spread

to

species

to

1.6.5).

eaten

this

and

by

ensures

9.6

for

this.

Many

bacteria.

the

produce

birds.

are

more

pollinated

that

plants

harmful

or

benefit;

are

animals

Similarly,

that

are

two

partners

flowers

bats.

of

flowering

of

of

the

legumes

These

plants

tree

with

species

have

bacteria

distinctive

that

live

swellings,

convert

in

fl owers

the

known

as

atmospheric

and

Caribbean

nodules

nitrogen

pod-like

are

that

(N

)

legumes.

contain

into

2

organic

use

a

to

forms

make

supply

within

of

the

of

nitrogen,

their

protein.

nitrogen

nodules,

in

such

This

organic

and

a

as

is

amino

acids,

mutualism,

form

supply

of

and

the

energy

that

the

because

bacteria

in

the

host

the

gain

form

plants

plant

of

gains

protection

Figure

1.6.5

This

bat

sugar

Pallas’s

is

long-tongued

pollinating

a

banana

flower.

(produced

Figure

by

the

1.6.6

a

plant)

The

swellings

root

are

(Figure

of

this

root

on

1.6.6).

the

b

legume

These

root

vertically

nodules.

where

nodules

to

show

have

the

nitrogen-fixing

been

pink

sectioned

areas

bacteria

inside

are

most

c

This

electron

inside

root

micrograph

nodules

are

shows

full

of

that

cells

bacteria

(× 300).

active.

SUMMARY

1

KEY

1

a

Define

POINTS

Any

form

of

close

relationship

between

two

or

more

species

QUESTIONS

the

following:

symbiosis,

commensalism,

parasitism

and

mutualism.

is b

Give

an

example

of

each

symbiosis. of

2

In

of

commensalism

the

species

species

(usually

live

the

together

to

the

benefit

of

one

these

explaining

smaller).

or

harm

species 3

A

parasite

from

the

lives

host

in

or

and

on

a

host

causing

it

species,

obtaining

its

In

mutualism

both

species

benefit

from

2

the

to

the

benefit

each

of

the

involved.

food

harm.

Make

the 4

relationships,

learning

different

notes

on

relationships

relationship.

described

to

help

here.

See

page

6

you.

21

Unit

SECTION

1

The

1

1:

most

Practice

Multiple-choice

common

reptile

exam

questions

questions

in

a

mangrove

4

A

student

used

a

quadrat

to

find

the

density

2

community

feeds

on

is

a

species

insects

of

Anolis

including

moth

lizard.

It

of

caterpillars

a

plant

quadrats

species.

were:

The

14,

6,

results

12,

8,

for

10.

five

The

1 m

mean

2

and

of

is

prey

bird.

mangrove

Which

of

trophic

food

to

the

Moth

pearly-eyed

caterpillars

thrasher,

feed

on

the

a

type

leaves

density

m

of

the

species

was:

A

8

B

10

C

12

D

15

trees.

the

level

following

of

these

correctly

four

identifies

organisms

in

the

this

chain?

5

Producer

A

per

of

Primary

Secondary

T ertiary

consumer

consumer

consumer

Anolis

pearly-

mangrove

moth

lizard

eyed

tree

caterpillar

Using

to

predators

reduce

the

and

parasites

damage

to

of

crop

pest

plants

species

is

known

as

A

biological

control

B

community

C

ecological

D

population

control

thrasher

B

pearly-

Anolis

moth

mangrove

eyed

lizard

caterpillar

tree

6

thrasher

Fungi

and

carbon C

mangrove

moth

Anolis

pearly-

tree

caterpillar

lizard

eyed

they

thrasher

D

moth

mangrove

pearly-

Anolis

caterpillar

tree

eyed

lizard

control

control

bacteria

and

are

nitrogen

important

in

in

ecosystems

recycling

because

are:

A

decomposers

B

herbivores

C

parasites

D

producers

thrasher

7 2

Nitrogen-fixing

bacteria

live

inside

the

Some

students

collected

a

soil

sample

in

a

tin

root 3

can nodules

of

legumes.

This

is

an

example

with

a

volume

of

400 cm

.

They

added

of 3

the A

soil

to

300 cm

of

water

in

a

beaker

and

commensalism stirred

B

decomposition

C

mutualism

found

to

remove

that

the

all

the

volume

air

of

from

water

the

and

soil.

the

They

solid

3

soil

particles

volume D

3

of

was

air

in

500 cm

the

soil

one

of

the

following

is

not

an

A

25%

B

40%

C

50%

D

71%

abiotic

factor?

22

A

oxygen

B

mineral

C

salinity

D

the

concentration

content

of

the

numbers

of

soil

of

of

the

in

a

river

water

soil

wetland

bacteria

in

a

ecosystem

soil

sample

8

Herbivores

are

A

primary

B

producers

C

secondary

D

tertiary

consumers

consumers

consumers

The

percentage

sample

parasitism

Which

.

was:

by

SECTION

9

Some

by

2:

Short

students

drawing

water ,

trees

a

began

line

across

50 m

answer

the

from

a

study

transect

beach

the

questions

of

from

to

a

beach

a

coastal

the

group

as

area

which

shallow

of

shown

acacia

in

are

urchins

Figure

are

1.

grazed

are

eaten

predators

and

eat

of

turtles,

i

Define

ii

Draw

the

a

Identify

B

Figure

C

D

1

iv

Describe

the

procedure

to

follow

Use

data

for

a

line

and

groupers.’

given

(1)

showing

in

the

trophic

The

students

regions,

i

A

State

the

ii

to

of

given

the

in

plants

used

in

of

pitfall

C

traps

why

D

of

were

The

to

in

the

information

to

explain

provided

the

the

B.

(2)

the

Some

meaning

a

students

Explain

investigated

living

what

(4)

Figure

2

is

in

leaf

the

litter

small

in

a

is

meant

by

the

term

(3)

a

diagram

of

a

pooter

mark–release–

the

study

traps

number

area.

are

numbers

caught

beetles

later

suitable

of

ground

and

marked

33

on

the

first

day.

how

students

they

caught

16

were

beetles

two

given

in

1.2

total

your

number

of

marine

other

of

to

working.

ecologist

the

seagrass

One

of

the

students

in

about

communities

that

Many

of

the

also

grass

the

in

noted

were

provides

turtles.

Many

how

the

grass

which

the

students

the

the

animals.

(4)

in

the

found

in

the

leaf

soil.

the

for

soil

provides

small

a

suitable

invertebrates.

(5)

Total

Caribbean.

15

marks

feeding

mentioned:

food

for

sea

organisms

including

these

ecology

practice

questions

urchins

live

on

photosynthetic

examples

can

be

found

the on

sea

(3)

area

and

and

in

invertebrates

live

Further

‘Sea

to

(3)

working

students

relationships

ways

collect

environment talked

pooter

beetles.

Explain A

a

to

litter all

use

invertebrates

of

b the

small

marked.

formula

calculate

would

T wo

could

d

2

Describe:

ii 7

Show

forest

found

collect

the

marks

ecosystem.

i ground

Use

25

(2)

students

which

the

(3)

Figure

days

of

ecosystem.

a

The

this

community

invertebrates

smaller

beetles.

ii

in

students

estimate

the

10

influence

area.

and

D.

1.

determine

beetles

pitfall

sampling

that

the

food

four

Figure

and

four

the

(4)

into

region

would

and

beetles

in

shrubs

region

method

Explain

for

trees,

ground

ground

i

of

in

factors

live

you

regions

recapture

shown

that

how

in

Nocturnal

as

area

(2)

when

transect.

the

abiotic

plants

Explain

living

D

two

density

c

divided

four

passage.

levels

have

the

between

Total b

catch

(4)

the

term collecting

Groupers

Humans

ecology.

chain

you

Sea

fish.

chain.

question a

term

the

organisms

A

parrotfish

relationships

organisms

iii

parrotfish.

puffer

parrotfish.

food

feeding

by

by

the

accompanying

CD.

algae,

23

2

The

impact

the

of

Waste

and

Have LEARNING

you

end

of

this

topic

•

be

able

distinguish

between

biodegradable

and

biodegradable

waste

discuss

the

recycling

of

so

body

broken

down

cannot

break

materials

indefinitely.

importance

and

data

management

the

In

difficulties

places

and

are

on

STUDY

FOCUS

Landfill

sites

in

the

you

produce

each

year?

(urine,

are

faeces

and

carbon

biodegradable

dioxide

wastes.

They

in

breath)

can

by

decomposers

down

many

Both

and

of

and

manufactured

wastes

types

(bacteria

remain

waste

can

in

be

fungi).

be

products

the

Decomposers

and

these

environment

hazardous

to

the

often

health

of

us.

with

good

treated

in

sanitation,

sewage

human

body

wastes

enter

sewers

works.

household

areas

These

their

are

managed

to

and

dumped

the

monitored

the

world

often

close

the

have

to

do

no

human

and

not

aquatic

regularly

dumps

have

for

good

habitats,

by

garbage

proper

disposal.

sanitation

drinking

organised

rubbish

habitation.

water

and

and

collection

Household

non-biodegradable

for

day

biodegradable

garbage

leaking

the

of

to

soil.

reduce

oxygen,

human

some

and

garbage

foods.

garbage

is

a

mix

rubbish

not

a

When

full,

material

is

not

sorted

and

removed

from

the

produced

is

warmth

total

and

volume.

damp

Decomposers

conditions.

need

Warmth

a

good

and

problem

in

the

Caribbean.

However,

garbage

is

water

usually

is so

much

that

there

is

not

enough

air

for

fungi

and

any bacteria

to

respire

efficiently,

so

biodegradation

is

rarely

complete.

vented Few

places

have

the

facilities

for

composting

wastes

(see

2.6).

burnt.

Plastic

forms

waste.

this

is

is

one

used

into

Plastic

T urtles

eat

of

for

problem

goes

space.

•

It

a

waste

the

largest

packaging

when

we

rubbish

waste

want

dumps

causes

plastic

components

because

to

or

special

containers

it

dispose

landfill

of

plastic

non-biodegradable

not

decay

plastics.

sites

problems

and

of

does

in

where

the

bags

it

sea

easily.

Most

takes

up

(Figure

mistaking

However ,

plastic

a

lot

2.1.1):

them

for

jellyfish.

•

Marine

wire

•

Figure

2.1.1

Non-biodegradable

collected

from

a

quantities

mammals

and

Plastic

netting

may

animals

waste

of

this

wildlife.

up

many

fish

get

trapped

in

discarded

that

ingested

plastic

suffocate.

into

build-up

in

tiny

food

pieces

are

by

small

chains.

Plastics

absorb

endanger

toxic

substances,

such

as

PCBs

(polychlorinated

rubbish

biphenyls) like

break

and

and

and

beach.

• Huge

24

of

waste.

liquid

compressed

methane

collected

surroundings

are

in

is

designated

materials

supply

Each

in

biodegradable

the

covered

to

environmental

Impermeable

them

rubbish

taken

contaminate

places

Often impact.

and

Caribbean.

is

and

waste

waste

wastes

waste.

much

of

Many

are

food

environment

collectors

line

how

doing

interpret

reduce

wastes

discarded

Similarly,

•

wondered

non-biodegradable

non-

manufactured

materials

ever

to:

the •

recycling

you and

should

management

OUTCOMES

Human

the

on

environment

2.1

At

humans

and

DDT

(dichlorodiphenyltrichloroethane);

marine

chemicals

persist

and

build

up

in

food

chains.

these

of

Difficulties

The

30

quantity

years.

and

not

of

to

solid

time

these

harm

dumped

In

problems

Toxic

The

partial

Methane

in

the

wastes

properly

managed

poor

waste

from

the

landfill

greenhouse

of

waste

to

legal

sites

that

tonnes

problems

over

the

past

non-biodegradable

of

is

generated

disposal

take

precautions

waste

(Figure

each

sites.

is

illegally

2.1.2).

There

disposal:

sites

the

taken

300 000

doubled

more

tonnes

are

environmental

ultimately

a

million

Almost

has

become

tonnes

into

surrounding

land,

water

sea.

decomposition

is

Caribbean

have

1.2

area.

severe

leak

and

management

828 000

local

with

liquids

waste

the

Jamaica,

are

the

causing

courses

•

waste

Approximately

None

•

of

Over

hazardous.

year .

are

in

of

gas

organic

(see

matter

produces

methane.

2.4).

Figure

2.1.2

Illegal

dumping

unsorted

•

Diseases

spread

from

waste

dumps.

Houseflies

transmit

diarrhoeal

diseases

like

sorts

of

environmental

typhoid. problems,

in

Waste

management

Integrated

waste

comprises

island

and

Deglos

clay

management

the

industrial

provided

eleven

landfill

piping

site

sanitary

upgraded

sanitary

lining,

from

an

one

and

and

both

collection

providing

a

system

two

and

kerb

site

ponds

tyre

and

zones,

garbage

a

site

at

at

in

St

that

the

are

to

run

100%

Waste

bins,

by

of

in

toxic

north

the

private

of

south.

The

The

site

are

leaching

also

has

services

organised

contractors,

Explain

YOU

Studies

with

an

are

levels

at

KNOW?

showed

in

the

autopsy

second

twice

livers

were

only

as

that

to

high

of

the

as

much

and

levels

in

nearly

the

UK.

thereby

POINTS

difference

between

biodegradable

waste

and

Decomposers

(bacteria

nonfungi)

break

the

over

volume

the

down

waste. biodegradable

has

high,

Japan

QUESTIONS

biodegradable

Why

Jamaicans

very

island.

and

2

cadmium

into

1 1

here

the

facility

substances

collection

and

the

the

KEY SUMMARY

shown

Belize.

Lucia

engineered

groundwater .

shredder .

which

in

Fort

purpose

prevent

communal

collection

Deglos

Vieux

nine-hectare

contaminating

autoclave

for

landfill

disposal

is

as

solutions

DID This

of

causes

diseases, all

e.g.

waste

past

of

30

waste

in

the

Caribbean

increased

into

so

carbon

ammonia

years?

waste

dioxide,

and

other

simple

compounds. 3

The

in

table

St

shows

the

quantities

of

waste

taken

to

the

two

sites

2

Lucia.

Non-biodegradable

cannot

Year

Waste

quantity

be

sanitary

landfill

Veux

Fort

disposal

waste

T otal

3

23 130

73 015

2005–6

59 426

22 191

81 617

2006–7

58 663

20 173

78 836

The

and

to

19 836

increase

rarely

reduce

bury

it

the

in

percentage

St

Lucia

increase

between

in

the

2004–5

quantity

of

waste

2007–8.

4

St

Outline

the

environmental

problems

of

the

in

seen

solid

the

wastes

facilities

quantity

in

a

and

sanitary

illegal

dumping

sites.

Lucia

waste

which 4

this

has

84 527

total

and

has

safely

landfill

collected

and

environment

Caribbean

huge

Calculate

the

indefinitely.

49 885

64 691

in

facility

2004–5

2007–8

waste

down

(tonnes)

persists

Deglos

broken

has

an

integrated

management

is

a

model

system

that

other

of

countries

could

follow.

rubbish.

25

2.2

The

impact

of

human

activities

Population LEARNING

The At

the

end

of

this

topic

be

able

world’s

19th

century.

discuss

global

population

and

rate

regional

fell

high

growth

on

distinguish

renewable

until

20th

significantly

century,

since

the

populations

middle

of

in

the

Caribbean

the

from

by

1–2%

the

1960s.

After

increased

per

1930s

this

even

year .

This

onwards

the

birth

though

was

while

because

the

death

rate

large

the

too

birth

rate

started

numbers

of

to

remained

decrease.

people

migrated

to

Panama,

of

increase

North

America

and

Europe

during

the

20th

century.

Rates

non-

now

vary

throughout

the

region

with

some

countries

having

resources

rates •

increased

the

between

and

renewable

average

steeply

Populations •

has

During

to: increased

•

population

you the

should

growth

OUTCOMES

describe

the

activities

on

impact

the

of

as

low

as

or

lower

than

countries

in

Europe

(Figure

2.2.1).

human

following

Resources natural

resources:

minerals,

forests,

energy,

As

fish

the

are •

discuss

the

effect

of

population

being

used

fish

stocks

in

outline

•

the

world

increases,

materials

fall

more

into

two

raw

materials

main

categories:

resources

and

non-renewable

resources

the

Caribbean

•

the

Raw

humans

renewable on

of

up.

effects

Renewable

Examples

of

molluscs

deforestation.

The

•

are

and

term

solar

resources

timber

for

wind

Non-renewable

is

be

replaced

building

crustaceans

‘renewable’

power,

can

and

harvested

also

energy,

by

making

from

applied

to

include

sea

forms

of

and

energy

and

paper,

the

hydroelectricity

resources

plants

animals.

and

and

fish,

from

energy,

lakes.

such

ethanol-based

sources,

such

as

as

fuels.

the

8.0

fossil

fuels,

and

minerals,

such

as

copper,

nickel,

zinc

and

lead.

7.0

When

we

have

used

these

resources,

they

are

gone

forever.

elpoep

6.0

5.0

fo

Fossil

fuels

4.0

snoilliB

3.0

Most

of

our

energy

comes

from

the

combustion

of

fossil

fuels,

which

2.0

will

1.0

run

out

eventually.

Caribbean

countries

import

most

of

their

1950

energy

as

oil

and

natural

gas.

Only

Trinidad

and

Cuba

have

reserves

0.4

since

2

human

increased

0

The

Oil

from

a

population

has

about

Catches

1850.

by

LINK

are

with

in

2.6;

the

exam

questions

some

data

on

tankers

run

aground

or

there

is

a

leak

in

the

Gulf

marine

of

Mexico

in

2010.

They

have

environment.

and

taken

Japan,

stocks

to

of

of

help

Venezuela

fish.

catch

storms.

foreign

of

late

have

the

dominated

1980s,

habitat

reefs

Reefs

Much

the

and

Coral

fish.

fleets

and

until

overfishing

coastal

other

by

increased

have

also

been

those

since

destruction.

been

region’s

by

but

blown

damaged

deep

sea

from

South

fish

T aiwan.

Minerals

practice

the

CD

have

populations

major

industry

is

bauxite

extraction,

which

is

concentrated

in

in Guyana

and

Suriname.

In

Jamaica

the

industry

has

had

severe

Caribbean. effects

26

as

the

because

habitat

dynamite

are

Jamaica, the

oil

population

The about

on

coastal

declined

the

hurricanes

Korea,

growth

platform,

effects

from

have

stocks

about

when

Fisheries

up

more

occur

exponentially

Reefs

is

drilling

devastating

AD

then

There

spills

0

2.2.1

oil.

9

Figure

0 0 9 1 0 0 7 1

1

1

5

0

0

0

0

0

0 0 5

Years

of

on

the

environment,

such

as

the

red

lake

at

Mount

Rosser

which

is

heavily

Dominican

in

a

Cuba,

huge

coastal

largely

where

area

of

have

land

Asia

years.

welfare

cleared

for

temperate

East

has

Deposits

companies

of

the

is

led

extracted

to

entered

have

carry

local

in

Cuba

environmental

the

Cabañas

destroyed

out

most

275

River

in

the

and

hectares

mining.

environment

and

degradation

the

They

of

have

past.

resources

Humans

provide

the

Nickel

has

waste

water .

Large

alkali.

mining

mining

coastal

ignored

with

Nickel

toxic

vegetation.

Forest

in

polluted

Republic.

regions

and

Many

Latin

of

forests

settlements

have

been

America

these

are

for

over

and

10 000

provide

affected.

have

been

years

to

transport

Tropical

cut

down

grow

links.

forests

over

food,

Most

in

the

forests

South-

past

100

rainforests.

Figure

There

has

been

large-scale

deforestation

to

provide

the

2.2.2

Deforestation

question

•

timber

•

paper

•

land

for

for

building

newsprint

cane

farms,

and

•

land

for

•

firewood

soya

and

other

forms

of

paper

and

and

cattle

ranches

and

plantations

of

oil

palms,

It

towns

and

charcoal

has

as

is

to

factories

Layers

of

soils

caused

vegetation

formation

degraded

is

in

very

term s

fuels.

environmental

tropical

removed

of

gullies

after

all

impo rtant

the

corre ct

when

problems

(Figure

answ ering

2.2.2):

rainforests

the

and

the

soil

loss

trees

is

of

are

are

very

washed

plant

cut

thin.

away,

When

causing

nutrients.

The

the

soil

land

is

term

good

erosion,

contex ts.

rapidly

see

how

Flooding

The

is

water

more

is

not

atmosphere.

the

rate

of

reaches

by

soil.

and

absorbed

Forests

act

evaporation

the

affected

frequent

Diego

flooding

as

by

from

Martin

because

as

plants

the

in

of

water

and

of

soil

runs

off

transpired

water,

and

their

the

Trinidad

is

into

leaves

rate

an

the

Many

habitats

are

destroyed

forests

are

•

even

When

been

studied

vegetation

atmosphere.

is

There

and

burnt,

is

at

which

example

in

as

roots,

that

some

Many

of

down

a

place

KEY

species

face

extinction

POINTS

The

human

species

in

rainforests

is

not

absorbed

carbon

releases

by

have

has

exponentially

since

not the

1850s.

Caribbean

dioxide

is

added

decomposition

of

to

populations

increased

significantly

in

the

plant

more

carbon

dioxide.

plants

as

they

have

been

the

20th

material,

This

cut

often

by

1–2%

a

year .

carbon

Increasing

population

puts

down.

pressure

SUMMARY

population

when

2 dioxide

it

book.

classified.

increased

also

this

water

century

such

revise ,

times

the

slow

about yet

a

severa l

deforestation.

and

destroyed.

is

in

you

man y

increased tropical

As

use

land.

1 •

to

down.

rapid

‘stores’

ques tions .

resou rces

word

appear s

•

(see

37)

TIP

know

T he

•

Belize

page

sugar

exam ination Deforestation

on

cardboard

beans

roads,

10

materials

EXAM

for

in

following:

energy,

QUESTIONS

on

resources

minerals,

–

forests

and

fisheries.

1

Outline

the

human

population

growth

over

the

past

500

years. 3

2

Describe

the

the

effects

on

the

environment

of

energy

provision

Fish

are

in

stocks

under

the

threat

overfishing

Caribbean.

in

and

Caribbean

from

habitat

destruction. 3

Explain

the

the

effects

of

overfishing

on

marine

environments

in

4

Caribbean.

Deforestation

has

environmental 4

Describe

the

impact

of

population

growth

in

the

Caribbean

such the

region’s

consequences,

on as

flooding.

forests.

27

2.3

Pollution

Anything LEARNING

that

At

the

should

end

be

released

of

this

able

topic

has

the

pollutants

you

carbon

to:

define

the

•

describe

term

and

products

•

discuss

the

by

practices

of

as

and

describe

aquatic

•

discuss

garbage

the

the

or

sources

from

Pollution

of

best

impact

much

or

of

to

type

if

to

drain

crops

of

it

are

such

material,

power

also

as

such

stations

pollutants.

activities

the

to

land

increase

to

use

Problems

fertiliser

are

causes

the

is

that

into

their

for

can

added

can

reef

mainly

short,

of

human

We

activity

think

fertilisers,

as

and

of

oil

human

noise

Pollution

are

harmful

rivers

yield.

their

occur

before

and

grows

reef,

faster

Do

we

pollute

have

this

the

right

egret’s

to

fairly

and

not

body

from

most

and

wastes.

industrial

is

to

the

the

release

of

environment.

and

lakes.

Fertilisers

are

if

a

Farmers

particular

a

farmer

period

of

need

soil

uses

to

and

too

heavy

know

crop

the

and

much

how

fertiliser

rain.

•

lead

from

•

mercury,

•

cadmium,

•

PCBs,

car

60%

and

not

coast

of

St

one

Kitts

of

keen

ecosystem

this

purple

to

see

with

tube

provide

pollution

ends

up

to

eat

the

them

plant

the

Caribbean,

in

the

sea

polyps

The

polyps.

so

with

In

Coral

symbionts.

energy

can

enriched

ions.

seaweeds.

as

causes

are

phosphate

as

microalgae

they

where

build

microalgae

The

seaweed

overshadow

photosynthesising,

so

the

reef

the

dies.

industry

produce

like

is

next

is

hot

build

used

is

large

water.

up

from

in

quantities

Others

food

and

gullies.

to

gold

of

are

waste.

taken

chains.

up

Some

by

Examples

of

these

organisms

are:

in

mining

industrial

products

such

improper

properly,

waste

in

used

making

rubbish

and

the

in

managed

other

not

The

mangroves

correctly

it

wastes

Riverton

in

and

has

electrical

such

as

anywhere

disposal

Jamaica.

the

a

as

garbage

thrown

produced

paints

It

building

site

Duhaney

huge

disposal

such

is

insulation.

as

near

119

rubble

into

Kingston

hectares

River.

As

environmental

the

should

rivers,

in

site

impact

receives

area

is

on

the

off

area

and

to

the

health

of

local

people

(Figure

2.3.1).

A

attract

wide divers

this

such

microalgae

so

which

used

surrounding the

and

This

waters

batteries

which

disposed

streams

this

pollution.

that

habitat?

be

like

from

processes

Household

reefs

of

herbivores

the

harmless,

Pollution

Coral

ions

algae,

and

excreted,

water

means

much

of

than

Pollution

are

nitrate

contain

preventing

Industrial

cause

which

so

growth

photosynthesise

28

result

ecotourism.

rivers

2.3.2

a

pollutant.

agriculture

fertiliser

fertiliser

nutrients,

Figure

from

from

eutrophication,

2.3.1

as

a

substances,

biological

human

from

add.

the

Excess

Figure

as

released

is

disposal

pollution

on

chemical

harm

of

environments

pollution

environment

cause

the

industrialisation

effects

domestic

substances

applied

•

being

heat

Fertilisers

improper

the

to

pollution

pollution

agricultural

potential

monoxide

However ,

•

into

OUTCOMES

the

riches

range

of

air

pollutants

are

produced

when

the

dump

burns;

diverse

like

sponge.

amongst

these

hydrogen

are

cyanide,

particulates,

nitrogen

such

oxides

as

dust,

(NO X),

carbon

sulfur

monoxide,

dioxide

and

dioxins.

The

public

health

•

water

pollution

•

pollution

•

heavy

•

pesticides

of

risks

into

Hunts

metal

from

the

Riverton

Duhaney

Bay,

which

contamination

for

use

in

are:

River

(used

scientists

from

eliminating

for

call

‘The

cadmium,

disease

drinking

Dead

and

Zone’

manganese

vectors

and

bathing)

and

plant

lead

KEY

POINTS

pests. 1

Pollution

is

the

substances

Pollution

and

the

marine

environment

are

three

important

marine

ecosystems

in

the

coastal

ecosystems

•

ecosystems

dominated

by

mangrove

shallow

water

where

sea

their

to

the

human

presence

in

environment.

trees

2 in

or

from

of

Caribbean:

the

•

harmful

environment

activities There

release

grasses

are

the

Agriculture

and

industry

dominant release

wastes

that

pollute

vegetation the

•

coral

reefs.

3

Mangrove

tropics;

trees

shrimp

building

protect

fishing,

development

coastlines

pollution,

have

and

estuaries

throughout

deforestation,

damaged

them.

storms

Sea-grass

the

and

in

shallow

waters

throughout

the

region

are

The

improper

garbage

coastal

breeding

sites

for

many

species.

They

too

are

important

at

from

pollution

and

Aquatic

with

reefs

over

are

a

one

of

million

consumption,

the

high

risk

protection

biodiverse

species;

for

they

coastlines

places

in

provide

and

are

a

the

fish

World

for

been

2.3.2).

In

the

tourist

reefs

have

Caribbean

been

it

is

estimated

that

over

destroyed

and

many

are

Some

scientists

have

predicted

that

coral

23%

considered

reefs

will

the

reef

end

off

from

of

the

land

the

coast

21st

of

run-off,

agricultural

century.

Tobago,

poorly

run-off,

Reefs,

have

treated

fertilisers,

such

been

as

the

severely

sewage,

herbicides,

at

Ecotourism

famous

domestic

by

have

had

removing

devastating

too

many

effects.

Overfishing

herbivorous

fish,

such

has

so

that

seaweeds

have

grown

as

and

grey

of

income

from

in

corals

of

sunlight.

Disease

has

also

also

out

graze

algae

on

coral

and

oil QUESTIONS

and

the

Make

a

table

sea

to

reefs

is

of

show

land,

air

and

urchins, In

your

table

state

the

reefs.

the threat

to

symbiotic

sources

Another

at

contributed,

water.

which

is

water,

parrotfi sh

wiped

many

It

pollution.

pollutants

algae

for

countries.

Pollution

chemicals

starved

important

Buccoo

1

surgeonfish,

an

high

SUMMARY

spills

is

disappear

degraded.

pesticides,

climate

of

risk by

and

change.

Caribbean risk.

by

development,

attraction

source coral

Caribbean

damaged

overfishing

human

5 (Figure

the

of

development.

most

different

hazards.

ecosystems

pollution,

Coral

of

and

feeding

have destruction

health

environmental

throughout and

disposal

poses

ecosystems

4 found

environment.

sea

water

becoming

more

acidic.

The

of

each

effects

pollutant

that

it

has

on

and

the

pH

environment. of

sea

such

water

as

has

clams,

decreased

to

make

making

shells

of

it

more

calcium

difficult

carbonate.

for

organisms,

The

same

applies 2

to

coral

polyps

that

secrete

the

calcium

carbonate

that

makes

State

some

pollutants,

the

skeleton

of

the

coral.

With

global

carbon

dioxide

this

is

likely

to

get

and countries

conserving

in

areas

the

like

Caribbean

these

for

have

the

realised

aesthetic

the

and

benefits

economic

bring.

Ecotourism

has

describe

the

effects

their

that

become

important

as

visitors

have

on

on

the

environment

humans.

of

benefits 3

they

and

worse. they

Many

and

concentrations sources

increasing,

industrial

up

from

a

Explain

the

term

abroad ecotourism

wish

to

see

the

spectacular

wildlife

associated

with

coral

reefs

and b

tropical

forests.

Pollution

has

a

negative

effect

on

such

areas

and

Outline

is cause

countries

like

Belize,

Dominica

and

Costa

Rica,

which

rely

why

ecotourism

can important

in

the

on Caribbean.

ecotourism,

to

lose

some

important

sources

of

revenue

and

income.

c

Explain

form

of

the

threats

to

this

tourism.

29

2.4

The

effects

climate

Life LEARNING

the

end

of

this

topic

be

atmosphere

able

explain

the

following

greenhouse

gases,

greenhouse

effect

terms:

keep

radiated

explain

greenhouse

what

climate

is

outline

of

the

climate

heat

a

blanket

gases

inside

space.

which

gases

meant

by

warm

in

surrounding

the

atmosphere

the

act

Earth

like

a

keeping

it

greenhouse.

the

atmosphere

These

are

are

carbon

greenhouse

that

otherwise

dioxide,

water

would

be

vapour

and

gases.

allow

it.

solar

Some

of

energy

this

to

pass

energy

through

enters

food

to

the

chains

Earth’s

and

is

surface

eventually

the to

the

atmosphere

as

heat.

This

radiates

away

from

the

Earth’s

change surface.

•

like

effect

lost

term

is

the

the

and

•

of

into

methane,

the

and

These enhanced

Some

to: They

•

greenhouse

you warm.

should

the

change

OUTCOMES

The At

in

of

likely

effects

change

on

the

and

Some

emitted

gases

keep

of

this

energy

towards

our

the

escapes

Earth

atmosphere

at

as

into

space,

infra-red

the

but

radiation

temperatures

much

is

(heat).

that

allow

absorbed

Greenhouse

life

to

exist.

environment. The

greenhouse

average

over

the

gases

DID

YOU

effect

temperature

last

from

100

on

years,

human

is

a

the

natural

Earth

there

processes

has

been

(Figure

greenhouse

gases

and

CFCs

the

oxides

CFCs

which

from

fertilisers

(chlorofluorocarbons),

were

also

a

and

without

about

build-up

it

–17 °C.

of

the

However,

greenhouse

2.4.1).

Ear th

used

in

destroy

upper

radiates

are heat

nitrous

be

KNOW?

The

Other

process

would

Radiation

the

Sun

the

Ear th

back

into

space

from

war ms

aerosols.

ozone

atmosphere,

Some

in

is

Space

which

H

absorbed

radiated

into

radiation

space

O 2

protects

us

from

the

harmful CH 4

effects

of

ultraviolet

light.

H

CO

O

2

2

CO 2

H

O 2

Greenhouse

gases

CO 2

CH 4

absorb

some

radiation

Atmosphere

CO 2

H

O

Most

2

is

Figure

EXAM

Do

no t

effec ts

CFCs

ozon e

confus e

of

Power

fossil

carbon

and

towards

Ear th

effect

stations,

me th ane

acid

due

to

and

transport

use

fuels

and

release

As

we

huge

have

amounts

seen,

of

carbon

deforestation

dioxide

has

into

resulted

in

the

large

of

forest

farming,

being

removed.

releasing

carbon

In

Latin

dioxide

America

into

the

the

trees

are

atmosphere

cleared

when

they

rain

sulfu r

po llu tion

atmos phere ).

heating

by

are

is

domestic

with areas

and

factories,

dioxid e,

destru ction

dioxid e

greenhouse

these

atmosphere.

(whi ch

of

burnt.

tree

parts,

Microbes

in

producing

the

even

soil

decompose

more

carbon

roots

and

other

remaining

dioxide.

the There

has

also

greenhouse

rearing.

the

anaerobic

extraction

been

gas)

Cattle

wetlands.

30

The

radiation

back

TIP

for

CFCs ,

2.4.1

absorbed

radiated

significant

to

excrete

the

oil

found

material

and

in

natural

increase

expansion

methane

conditions

Rotting

of

a

due

and

in

in

are

methane

rice

bacteria

flooded

landfill

gas

of

sites

other

also

rice

and

(another

cultivation

release

fi elds

and

rubbish

sources

of

and

it

cattle

in

natural

tips

and

methane.

the

Of

all

the

dioxide,

greenhouse

which

molecules

of

greenhouse

The

air

effect

warm

energy

other

a

than

Climate

Human

activities

the

between

If

the

the

are

by

flooding

such

increase

last

a

30

much

carbon

in

the

dioxide

back

out

as

has

been

years.

greater

water

space.

of

methane,

question

on

on

causes

vapour

Human

carbon

which

9

carbon

impact

atmosphere

into

in

However,

the

dioxide.

and

atmosphere

(see

the

average

by

2039,

2070

ice

of

causing

so

0.7 °C

and

temperature

polar

of

gases

the

dioxide

enhanced

that

0.5–1.0 °C

in

gases,

gases

warmed

suggest

have

carbon

straight

increase

the

a

heat

activity

dioxide

has

the

the

the

is

and

greater

CD).

change

greenhouse

causing

largest

in

CFCs

greenhouse

carbon

the

10%

molecules

Without

pass

large

by

and

than

greenhouse

impact

has

of

up.

would

causing

gases,

risen

methane

presence

to

has

many

increase

is

greenhouse

over

the

past

temperatures

0.8–2.5 °C

in

the

effect.

century.

in

from

concentration

getting

the

warmer.

The

surface

Global

to

of

climate

Caribbean

2040

This

2069,

will

the

Earth

models

rise

and

of

is

by

0.94–4.8 °C

2099.

of

would

an

atmosphere

the

start

Arctic

to

and

melt.

low-lying

Antarctic

This

areas.

would

These

were

to

cause

would

a

rise

rise

include

above

in

sea

most

0 °C,

level

of

the

and

capital Figure

cities

of

the

Caribbean

and

much

of

the

region’s

farmland

(Figure

2.4.2

If

2.4.2).

sea

areas

of

There

could

also

be

a

change

in

wind

patterns

and

the

the

rainfall,

world

are

leading

agricultural

climate

Asia

areas,

could

and

to

expected

a

extreme

become

such

mean

North

more

to

as

parts

massive

America.

very

The

of

weather.

dry.

the

USA

reduction

pattern

Some

Some

of

in

of

and

the

the

parts

these

Asia.

grain

world’s

of

are

be

affected

with

economic

and

political

the

Warming

crops

food

St

of

of

to

reduce

the

effects

of

global

emissions.

and

Strategies

using

to

do

and

power

renewable

this

warming

of

and

ethanol-based

involve

Caribbean

is

at

high

risk

of

in

be

in

lost.

Carbon

using

energy

energy

such

dioxide,

methane

reducing

CFCs

as

are

greenhouse

more

solar,

that

absorb

infra-red

wind

from

the

Earth

and

fuels.

emit

The

could

here

POINTS

radiation wave

Lucia,

as

consequences.

include

sources

Caribbean,

Central

gases efficiently

most

facilities

distribution

and carbon

tourism

the

1 Measures

low-lying

important

KEY could

rise,

provide

distribution the

of

levels

that

storm

damage.

The

severity

of

it

back

to

heat

up

the

tropical atmosphere.

storms

has

been

increasing,

with

eight

Category

5

hurricanes

between

2 the

years

2001

and

2010,

compared

with

a

total

of

23

between

The

greenhouse

maintains and

2000.

Storms

are

also

reaching

high

intensity

more

quickly.

storms

will

increase

damage

to

the

mangroves.

If

the

provided

by

mangroves

is

lost,

erosion

happens

the

more

a

Define

b

Name

term

greenhouse

greenhouse

Explain

what

3

Describe

is

meant

by

gases.

the

the

in

result

the

greenhouse

Global

climate

involves

sea 2

steps

that

can

be

enhanced

greenhouse

taken

to

reduce

carbon

specific

examples

to

outline

of

an

gases.

the

likely

effects

of

change

temperatures

air

and

and

more

weather,

such

emissions. more

and Use

exist.

effect

as

4

can

concentration

increased

unpredictable

the

life

greenhouse

gas 3

two

is

increase

QUESTIONS

the

so

quickly.

of

1

Earth

enhanced

effect

SUMMARY

temperature

coastal

The protection

the

More

of severe

effect

1928

frequent

storms

and

hurricanes

rises

in

sea

global

level. climate

change

on

island

states.

31

2.5

Conservation

Reducing LEARNING

Farmers At

the

end

of

this

topic

be

able

can

describe

impact

in

which

agriculture

environment

can

be

not

the

on

the

reduced

use

outline

methods

use

of

agriculture

the

use

effect

of

that

fertilisers

chemicals,

such

have

as

on

the

fertilisers,

environment

pesticides

and

the

They

should

as

agriculture,

natural

to

soil

to

of

apply

‘just

which

methods

the

only

insurance

in

does

not

fertilising

decay

the

chemicals

case’.

use

crops.

naturally.

Some

when

farmers

chemicals.

Animal

Farmers

plant

also

and

turning

Organic

and

can

necessary

are

to

farmers

wastes

reduce

the

are

use

for

of conserving

the

them

organic

added •

impact

to:

ways

of

reduce

controlling

herbicides.

•

environmental

you by

should

the

OUTCOMES

pesticides

by

using

biological

control

(see

1.5).

natural

environment

•

outline

methods

degraded

land

for

and

restoring

Conservation

As aquatic

(marine

we

have

seen

Our

producing

that

we

benefit

the

very

world

existence

of

future

of

But

genetic

it

should

provides

many

of

our

renewable

depends

on

the

Other

We

No

like

this

large

set

ocelot

areas

aside

of

and

of

for

have

a

species

activity

of

wastes.

It

organisms

have

a

benefit

duty

area,

a

different

of

as

well

care

species.

country

habitats

or

in

is

to

fully

to

habitats

services,

and

giving

substances

maintain

•

Protecting

a

wide

the

have

role

by

as

in

by

as

and

such

us

such

species

as

Biodiversity

the

area

for

treating

areas

as

balance

keeping

for

is

a

whole

and

the

the

waste,

recreation.

They

medicines.

of

life

–

large

wardens.

of

so

Here

tracts

Parks

vital

pests

to

the

we

are

of

organisms

are

right

guardians

isolation,

of

but

much

habitats.

Parks

variety

understand,

example

and

National

on

the

planet,

e.g.

and

live

have

a

some

also

this

duty

to

in

aside

be

interact

in

in

life

ways

on

this

check.

planet

(Figure

ways

set

that

continuing

diseases

on

planet

land

may

for

as

we

do.

2.5.1).

conserve

which

for

this

wildlife

occupied

by

is

done:

and

people.

species

areas

of

the

sea

from

damage

from

fishing

and

pollution

requires

land

to

by

be

establishing

marine

parks.

protected

deforestation

Rescuing

endangered

animals,

breeding

them

in

captivity

and

returning

them

to

the

wild.

development.

•

Growing

endangered

establishing

32

the

maintain

even

an

important

as

species.

with

fuels

useful

help

lives

•

• from

us

and

with

species

patrolled conservation

an

the

each

our

endangered

in

ecosystems,

provide

support

not

ecosystems

The

includes

for

our

cycles.

Habitats

planet,

•

We

protect

species

within

food

us

nutrient

do

environment

and

the

conserve

Ecosystems

we

decomposing

generations.

also

Ecosystems

provide

•

the

and

reasons:

providing

•

all

diversity

following

•

food

biodiversity

world.

We

our

conserve

catalogue

2.5.1

natural

environments. in

Figure

the

and resources.

freshwater)

methods

damaged

them

in

plants

the

in

wild.

botanical

gardens

and

re-

and

then

•

•

Reducing

habitat

forests

preventing

or

Encouraging

allowing

but

•

not

seeds

store

seeds

wild.

Their

or

produce

Removing

bottle

from

habitats

Rica,

•

T ree

•

Restoring

•

Restoring

the

logging

in

useful

the

when

in

species

they

crop

such

at

hope

forests,

are

very

to

removed

become

low

collect

extinct

improvement

as

dodder

In

trees

areas.

world

case

for

as

ecosystems.

large

valuable

products,

following

day

lake

may

in

the

land

been

in

and

in

the

the

future

drugs.

(see

are

1.6),

lionfish

and

take

Jamaica

severe

at

Mount

land

forest

up

to

and

effects

by

is

or

destroyed

an

by

important

part

of

examples:

where

dry

degraded

degraded

catastrophes

ecosystems

which

reduce

soda

have

natural

establishing

planting

to

that

and

The

example

land

or

around

such

of

replanting

clearing

species

be

species,

Re-establishing

Costa

for

methods

activities

conservation.

for

may

licences

brush.

Restoring

•

many

valuable

Restoration

human

banks

or

by

endangered

genes

issuing

management

habitats

Seed

alien

e.g.

altogether.

replacement

of

temperatures.

•

it

sustainable

natural

destroying

Storing

to

destruction,

in

300

of

in

become

years

schemes

heavy

mining

Rosser

has

Guanacaste

in

to

to

reforest

(Figure

waste

Park

in

achieve!

Haiti

rain

and

degraded,

National

degraded

2.5.2).

disposal,

for

example

Jamaica. Figure

mangrove

to

protect

coasts

that

are

at

risk

of

storm

2.5.2

No-one

to

damage.

is

plant

mango,

Education

of

and

public

conservation

awareness

work.

Much

campaigns

can

be

are

achieved

an

by

important

people

in

part

their

fruit

in

legislate

habitat

to

restoration

protect

habitats

and

at

conservation.

risk

from

Governments

development

and

can

using

need

energy

to

be

conserved

efficiently

may

as

well.

conserve

We

fossil

have

fuels.

already

aluminium,

glass

and

paper

reduces

energy

discussed

Recycling

environment

(by

creating

less

waste)

and

materials,

consumption,

saves

raw

are

globally

becoming

has

increased

exhausted

or

considerably

polluted.

and

Water

materials.

many

must

not

must

be

used

sensibly

so

that

everyone

may

have

to

erosion.

T aking

steps

use

of

reduce

fertilisers

and

Water

sources

be

to

to

by

integrating

of use

with

biological

wasted control

and

other

help

such

damage

their

water

will

POINTS

pesticides

consumption

provide

for

how

the

the

soil

and

this

also

1

as

will

destruction.

KEY Resources

like

habitats

organisms

own

young

tree

which

and

reduce

locality

too

a

can

reduce

the

some. impact

of

agriculture

on

the

environment.

SUMMARY

QUESTIONS 2

Conservation

protection 1

Outline

how

the

effects

of

agriculture

on

the

environment

ecosystems

Suggest

how

resources

3

Explain

individuals

and

how

can

promote

conservation

depletion

of

damaged

environments

can

be

3

restored.

Tree

Discuss

the

benefits

of

Suggest

ways

restoration

in

can

which

be

control

and

planting

tree

soil

prevent

the

helps

erosion,

to

provides

planting. habitats

5

maintain

extinction.

energy.

reduce 4

to

reduced. biodiversity,

2

the

management

can of

be

is

and

success

monitored.

of

conservation

and

habitat

and

for

other

restores

organisms

degraded

habitats.

33

2.6

What

will

the

future

bring?

Population LEARNING

Populations At

the

end

of

this

topic

be

able

of

outline

the

influence

including

animals,

resources

plants

and

space

and

microbes

available.

increase

However,

if

there

there

are

are

certain

to: factors

•

of

you plenty

should

growth

OUTCOMES

factors

that

limit

the

maximum

numbers

in

a

population.

These

are:

that

population

reference

•

availability

of

•

competition

food

and

water

growth

to

for

space,

food,

water

and

mating

sites

(e.g.

nesting

invasive

sites

for

birds)

species

• •

outline

the

factors

that

disease

rapidly human

population

explain

the

projections

human

globally

discuss

challenges

environmental

and

do

that

on

of

solutions.

a

species

competitors,

species

much

of

natural

Since

the

the

living

The

has

Department

encouraging

lionfish

people

than

more

on

on

larger

populations

than

environment,

no

disease.

the

in

and

new

small

1.5.

feeds

have

Indian

The

from

or

in

other

environment

may

are

be

invaded,

(Figure

the

a

and

has

examples

new

in

the

2.6.1)

USA.

species

no

many

mongoose

lionfish

aquaria

on

there

There

of

It

comes

has

fish.

It

increased

from

colonised

has

in

no

numbers.

human

on

populations

our

numbers

and

Many

are

infectious

predators.

to

there

More

began

have

shows

better

diseases

people

overconsumption

pandemic

us

to

of

that

grow

been

exponentially

reduced.

facilities

have

demand

Food

for

been

storage

and

controlled.

higher

standards

We

of

resources.

population

there

and

may

other

increase.

come

a

time

diseases

With

we

are

not

when

that

are

antibiotic

completely

resistance

free

antibiotics

currently

are

curable

no

on

the

longer

become

There

flesh

as

one

controlling

more

about

this

in

12.2.

are

also

concerned

identical.

This

that

makes

our

it

main

highly

crop

likely

plants

that

are

too

diseases

of

crops

approach

wheat,

maize

and

rice,

will

wipe

out

all

the

different

varieties

numbers.

of

exist,

seeds

as

plants

LINK

2.2

to

population

remind

yourself

growth.

An

wild

They

of

banana

are

varieties

of

to

what

plants

reproduction,

varieties

may

resistance

example

new

those

from

important.

to

is

to

that

34

spread

in

like

back

diseases

populations

KNOW?

Fisheries

about

effect

introduced,

of

increased

lead

to

genetically

Go

its

foods.

HIV/AIDS

checks

Scientists

to

in

any

which

incurable.

eat

greater

and

escaped

checks

have

effective

is

and

1850s,

the

increase,

Jamaica

large

lionfish

of

The

a

new

been

effects

Caribbean

transporting

YOU

number,

populations

production

not

a

described

predator

because

do

have

The

Asia

Human

DID

have

predators

were

South-East

The

in

on

populations.

invades

no

that

Caribbean

2.6.1

also

smaller

environment.

Figure

effect

ones

predators

When

future

increase

greater

and

regionally

•

a

population

they growth

populations

have

for

• future

as

and

growth

small •

–

affect

all

our

genes

crops

that

very

and

we

can

similar.

from

use

The

local

to

collection

varieties

give

our

is

crop

diseases.

might

by

the

have

genetically

happen

taking

plants

stem

are

is

the

banana.

cuttings.

genetically

As

Farmers

this

identical.

is

a

propagate

form

The

of

asexual

Cavendish

variety

to

of

two

the

fungi

cannot

by

banana

diseases:

that

be

cause

like

the

Projections

global

increasing

birth

in

rate

the

has

for

any

global

dropped

in

will

people

other

Michel

rate,

but

be

an

in

way,

variety

and

has

not

ageing

the

land

resistant

in

the

reached

the

to

is

susceptible

2.6.2).

fungicides

will

20th

7

In

be

If

and

wiped

out

century.

billion.

some

past

countries

population

it

populations

everywhere.

over

and

(Figure

Cavendish

was

just

of

sigatoka

local

Caribbean

the

areas

black

become

remarkably

some

than

huge

and

diseases

population

fast

rate

there

elderly

a

in

across

disease

these

Gros

human

at

birth

future

grown

controlled

disease,

The

is

Panama

few

means

with

a

It

is

still

countries

decades.

that

higher

in

the

The

the

fall

near

proportion

of

past. Figure

2.6.2

A

banana

with

Challenges

If

our

species

growth

and

standard

of

resources

cane

is

We

in

are

should

waste

to

living.

and

which

a

in

We

is

to

of

to

to

make

of

to

our

use

of

waste

make

a

valuable

resource

for

agriculture

and

be

the

to

collect,

biodegradable

cannot

energy

threats

be

composted

or,

to

as

a

the

separate

waste

last

or

and

(Figure

2.6.3).

to

Sugar

make

Nuclear

totally

by

caused

power

pollution.

by

composted

This

recycled

resort,

buried

environment

are

could

in

household

into

compost.

be

is

We

Figure

2.6.3

Fossil

improper

to

fuels

landfill

of

energy

solar

every

solution

brings

its

to

that

KEY

produce

where

the

1

Factors

that

they

burn

and

in

some

places

there

is

no

market

toxic

for

is

in

a

form

many

of

hunting.

parts

of

the

Fish

farming,

world,

notably

or

aquaculture,

in

South-East

countries

have

invested

in

aquaculture,

is

some

farms

that

rear

the

fast

growing

tilapia

although

fish.

we

started

to

farm

fish

as

we

did

cattle,

sheep

Human

it

water ,

predation.

populations

by

same

goats

these

are

not

factors

extent.

The

to

HIV/

pandemic

is

an

example

many a

factor

that

is

limiting

ago. human

SUMMARY

3

QUESTIONS

population

Human

Explain

why

a

population

of

organisms

does

not

this

increase

the

indefinitely.

growth.

populations

growing

1

and

resources,

is

of

millennia

for

there

Perhaps

and

food

are:

Few

AIDS

time

houses

practised

Asia.

the

are

to

buildings.

influence

of

and

affected

Caribbean

these

compost.

2

widely

use

fitting

gases

disease

Fishing

like

commercial

growth

competition

when

by

POINTS

population

Plastics

last

make

provide

minimised.

problems.

can

while

waste

availability

But

not

We

provide

waste,

sites

will

forever.

needs

The

incinerated

sanitary

that

sigatoka.

France.

horticulture.

store

decomposes

black

population

and

organisation

infected

reasonable

panels

a

plant

fungus

non-renewable

gasohol.

like

problems

can

reduce

with

fermentation

environment

the

of

to

energy

for

countries

solve

Biodegradable

to

way

everyone

better

sugar

petrol

ruining

some

sources

provide

with

find

support

industrialised

technology

disposal.

must

renewable

mixed

danger

apply

need

Brazil

number

we

resources

develop

in

causes

solutions

survive,

provide

grown

ethanol,

used

is

and

the

at

a

presents

high

are

rate

problems

environment

and

and

for

human

health. 2

Outline

billion

the

problems

facing

a

world

population

in

excess

of

7

4

people.

Population

slowing 3

Summarise

the

environmental

problems

facing

your

Suggest

ways

problems

you

in

which

have

new

technology

identified

in

may

question

3.

solve

many

is

countries

country. in

4

in

growth

some

of

the

if

the

this

Caribbean;

will

be

proportion

an

of

the

impact

increasing

elderly

people.

35

Unit

SECTION

1

The

1:

Practice

Multiple-choice

concentration

Earth’s

2

2

Which

of

of

increase?

this

the

A

increase

B

less

C

more

D

melting

Which

of

carbon

has

following

in

sea

dioxide

increased

is

the

in

the

5

significantly.

most

likely

cause

levels

combustion

of

the

human

ice

of

in

causes

the

toxic

fossil

fuels

caps

activity

waters

drainage

of

questions

questions

photosynthesis

coastal

A

of

atmosphere

exam

eutrophication

6

Species

that

successfully

habitat

are

known

species

are

more

in

new

their

competitors

B

limited

C

no

D

parasites

colonise

invasive

likely

habitat

A

Tree

as

if

to

a

become

they

new

species.

These

established

have

resources

predators

planting

is

an

example

of

Caribbean?

compounds

from

A

conservation

B

environmental

C

organic

C

recycling

rubbish monitoring

tips

B

overuse

of

fertilisers

in

C

overuse

of

pesticides

D

pollution

adjacent

7

3

Different

to

see

fish.

50%

the

pest

how

The

of

by

control

chemicals

poisonous

the

fish

dose

In

1900

the

population

of

Guyana

was

oil

they

concentration

lethal

farming

farmland

within

50

of

were

were

to

pesticide

four

(LD50).

days

The

is

tested

287 000.

By

769 000.

The

freshwater

population

that

2010

kills

known

table

2010

this

had

percentage

of

Guyana

increased

increase

between

in

to

the

1900

and

was:

as

shows

A

32%

B

37%

C

63%

D

168%

the

results.

Pest

control

LD50/parts

chemical

per

million

8

A

DDT

B

dieldrin

C

malathion

D

parathion

Which

most

0.01

chemical,

serious

to

of

the

following

influence

the

growth

12.20

2.11

A,

effect

B,

on

C

or

D,

will

freshwater

contaminate

a

have

fish

A

competition

B

diseases

The

quantity

Caribbean

C

light

of

solid

countries

not

directly

A

burying

it

all

B

composting

in

be

sanitary

the

C

incinerating

D

introducing

the

collected

reduced

landfill

biodegradable

D

predators

for

food

if

Which

an

is

the

island

best

definition

of

the

biodiversity

in A

all

the

B

the

C

all

species

living

within

the

country

genetic

diversity

of

all

the

species

sites

the

different

ecosystems

wastes and

offshore

wastes D

schemes

state?

by:

non-biodegradable

recycling

animal

river?

wastes

can

an

intensity

island

36

does

the

of

4

of

population?

9 allowed

Which

0.03

all

of

the

above

within

the

SECTION

10

a

2:

Short

‘Tropical

Explain

answer

forests

this

have

questions

great

biodiversity.’

statement.

f

(3)

Fish

are

two

ways

an

conserved Scientists

have

to

the

used

satellite

imaging

important

in

which

for

the

resource.

fish

stocks

Suggest

can

(2)

techniques

Total follow

b

List

four

loss

of

forests

reasons

countries

in

the

for

all

over

the

Belize

1

and

2

deforestation

in

11

Caribbean.

show

between

the

1980

loss

and

marks

a

i

Define

the

term

ii

Distinguish

pollutant.

(1)

(4)

of

forest

cover

between

biodegradable

non-biodegradable

waste.

(2)

in

2010.

b

Make

and T able

25

world.

and T ables

be

future.

a

table

effects

to

of

show

three

the

sources

named

pollutants

1

that

have

significant

effects

on

the

2

Year

Forest

1980

cover/km

environment

in

the

The

of

solid

region.

(3)

16 834 c

1989

16 443

1994

15 452

2000

14 652

quantity

Caribbean

over

14 153

2010

13 900

d

years.

of

Outline

the

reasons

for

the

waste

increased

such

in

the

considerably

Suggest

governments

quantity

2004

has

recent

regional

T able

Caribbean

ways

can

in

reduce

which

the

waste.

(4)

environmental

conserving

and

natural

economic

habitats

in

region.

(5)

2

Total

Years

Area

deforested

15

marks

Percentage

12

Coral

reefs

are

polluted

by

water

draining

2

each

year/km

loss

per

year

from

1980–89

12

–0.3

1989–94

207

–1.4

71

–0.9

2000–04

291

–0.9

2004–10

61

–0.3

farmland.

fertiliser

a

1994–2000

Describe

coral

b

and

As

a

result

they

often

receive

sewage.

the

effect

of

this

pollution

on

reefs.

Describe

(5)

two

other

threats

to

coral

reefs.

(4)

c

Data

adapted

Belize

from

SERVIR:

Forest

Cover

and

Deforestation

i

in

State

three

become

reasons

why

organisms

extinct.

(3)

1980–2010

ii

Scientists

have

suggested

that

some

2

c

The

total

land

mass

of

Belize

is

22 167 km animals

Use

i

the

the

of

data

Belize

that

showing

the

the

percentage

and

ii

in

that

mean

of

was

which

your

tables

calculate

total

forested

was

land

in

forested

recent

mass

2010,

area

between

of

(4)

Belize

1980

and

that

was

DNA

have

be

become

‘brought

techniques

from

cloning.

One

back’

including

museum

such

extinct

is

the

Discuss

d

the

Outline

mean

the

continued

percentage

environmental

deforestation

in

loss

per

year.

consequences

the

rights

and

wrongs

Explain,

using

between

examples,

renewable

resources.

and

such

(3)

15

marks

of

Belize.

the

of

(2)

(6) Further

e

and

Cuban

programme.

Total iii

using

isolation

specimens

animal

in

macaw.

a

2010

times

modern

of

1980

in

working.

annual

deforested

the

to

that

distinction

and

non-renewable

on

practice

examples

the

questions

can

be

found

accompanying

CD.

(4)

37

3

Cells

3.1

Plant

LEARNING

At

the

end

Cell

structure

Cells

are

be

of

this

topic

able

describe

the

generalised

cells

and

between

of

sometimes

cells.

structure

animal

state

the

and

significant

animals,

of

plant

differences

between

membrane

is

quite

and

identify

cell

organelles

of

see

and

and

and

contain

Even

that

them.

of

in

life’,

as

all

common,

organisms

although

are

there

Figure

with

are

not

between

bacteria

the

are

cytoplasm,

3.1.1

very

shows

and

but

the

light

we

types.

surrounded

plant

powerful

visible

different

all

rest

cells

of

seen

the

an

a

from

cell

cell

structure

through

microscopes

need

Cells

by

electron

there

a

light

are

cell

microscope

Figures

taken

3.1.2

with

and

3.1.3

electron

have

been

microscopes

drawn

that

from

allow

us

to

see

in structures,

called

organelles,

found

within

cells.

diagrams

cells Animal

•

‘units

features

walls

these photographs

fungi

different.

photographs •

the

share

cell

to membranes

called

cells

differences

plants,

microscope.

them

distinguish

All

to:

structures •

cells

you

are

•

animal

OUTCOMES

made should

and

distinguish

and

plant

cell

structure

between

chloroplasts

and

mitochondria Cell

Microvilli

•

relate

the

structure

Endoplasmic

organelles

to

their

wall

of

functions.

with

reticulum

ribosomes

Chloroplast

Cytoplasm

Cell

membrane

Mitochondrion

Large

vacuole

Nucleus

Small

vacuole

Ribosomes

Figure

Figure

3.1.1

Cells

have

they

cell

are

from

a

are

pond

shape

weed

of

STUDY

by

These

leaf

cells

green

organelles

Make

large

38

cell

can

drawings

3.1.2

and

annotate

Figure

3.1.3

of

unspecialised

3.1.3),

the

and

use

drawings

by

plant

them

for

adding

and

your

1000).

A

plant

cell

of

each

structure

you

have

animal

labelled.

cells

revision

information

chloroplasts

functions (×

animal

FOCUS

(Figures

You called

An

because

surrounded

walls.

full

a

fixed

3.1.2

notes.

about

the

Functions

T able

of

cell

3.1.1

Cell

structures

structures

and

Cell

structure

Functions

Cell

wall

•

(plants

only)

their

made

from

when

they

•

gives

•

allows

pass

membrane

cellulose;

are

fixed

and

through

•

forms

a

•

keeps

•

allows

full

–

to

barrier

cells

from

bursting

water

cells

dissolved

freely

see

stops

of

shapes

water

permeable

Cell

functions

(often

substances

described

to

as

freely

3.4)

between

cells

and

their

surroundings

cells,

•

contents

simple

e.g.

controls

out

of

of

cells

oxygen,

e.g.

to

carbon

movement

cells,

inside

substances

of

enter

dioxide

other

glucose

and

and

leave

water

substances

and

into

and

Figure

3.1.4

A

chloroplast,

organelle

ions

that

the

carries

photosynthesis

•

often

(see

Nucleus

described

•

holds

•

controls

all

•

controls

how

•

place

e.g.

the

chromosomes,

in

the

cells

carries

Chloroplast

•

carries

(plants

•

stores

which

of

carry

•

plants

DNA

inside

(see

11.3)

cells

chemical

and

reactions

making

out

aerobic

out

photosynthesis

proteins

respiration

take

for

(Figure

(Figure

place,

cells

3.1.5)

3.1.4)

starch

Figure

3.1.5

A

mitochondrion,

–

large

and

full

of

water

to

where

and

‘firmness’

of

within

–

small

and

stores

enzymes

for

digestion

State

are Remember

to

include

a

column

headed

‘Features’

when

four

found

your

Similarly,

table

comparing

remember

question

this

if

plant

you

and

decide

animals

tables

cells

are

a

in

question

good

structures

in

both

that

plant

and

you animal

answer

QUESTIONS

FOCUS 1

make

40 000)

cells SUMMARY

STUDY

occurs

cells (×

animals

the

aerobic

maintain respiration

shape

•

out

10 000)

genetic

organelle

Vacuole

(×

permeable

develop

many

respiration

•

form

activities

where

Mitochondrion

only)

differentially

3.4)

information

Cytoplasm

as

way

cells.

2.

to

2

3.

Make

a

table

structure

of

to

compare

plant

and

the

animal

cells.

3 KEY

Distinguish

each

1

Some

cell

details

only

structures

of

be

these

seen

can

be

structures

with

an

seen

and

electron

with

some

the

very

light

small

microscope;

structures

can

microscope.

Animal

and

plant

cells

have

cell

membranes,

nuclei,

of

pairs:

and

cell

chromosome

membrane;

nucleus.

You

wall

could

and

use

cytoplasm for

this

question

and

mitochondria. add

3

following

chloroplast

cell

tables and

the

mitochondrion;

and 2

between

POINTS

Plant

cells

vacuoles.

have

cell

Animal

walls,

cells

do

chloroplasts

not

have

and

these.

large,

central

more

these

information

structures

through

the

rest

as

of

about

you

this

work

unit.

39

3.2

Microbes

Microbes LEARNING

OUTCOMES

Bacteria, At

the

end

of

this

topic

fungi,

viruses

microorganisms should

be

able

state

that

viruses

bacteria,

and

do

fungi,

protists

not

do

not

of

these

the

just

protists

are

microbes

structure

groups

of

of

is

similar

to

chloroplasts.

than

have

animal describe

that

have

smaller

are

microbes

•

or

often

for

known

short.

as

Fungi

have

a

cell

to: structure

•

and

you

plant

cells

and

at

the

structure

Bacteria

animal

all.

do

cells.

Protists

of

not

plant

have

Viruses

have

more

are

in

cells

except

nuclei

quite

and

that

are

different

common

with

they

much

as

they

plant

and

cells.

each

microbes

Bacteria •

state

the

similarities

differences

different

and

between

groups

of

Each

the

microbes.

You

there

and

no

bacterium

can

see

are

only

plant

are

a

cells.

nucleus;

there

is

that

the

no

made

the

of

cell

few

of

Their

the

a

cell

cell

cell

genetic

cytoplasm

other

one

has

and

wall

structures

material

contains

structures

is

described

and

is

a

cell

you

in

can

the

ribosomes

(Figure

as

unicellular.

membrane,

see

in

the

cytoplasm

to

make

as

but

animal

there

proteins

is

but

3.2.1).

Cytoplasm Stored Cell

wall

food

Fungi Cell

reserve

membrane

Ribosomes

Yeast

is

yeast

cell

ways

a

fungus

has

yeasts

a

that

is

also

nucleus,

are

like

unicellular,

mitochondria

plant

cells

except

but

and

that

a

unlike

large

they

bacteria

vacuole.

have

no

each

In

many

chloroplasts.

Flagellum A

loop

of

Plasmid

Figure

3.2.2

shows

a

mould

fungus.

Many

of

these

do

not

have

DNA

separate

Figure

3.2.1

A

bacterial

cell.

are are

small

loops

cells

at

all

but

long

thin

threads,

known

as

hyphae

which

Plasmids

of

not

sub-divided

into

cells

but

contain

all

the

structures

in

one

DNA.

long

‘tube’.

Genetic

Nucleus

Mitochondrion Endoplasmic

Protein

Surface

coat

proteins

reticulum

Ribosomes

Figure

3.2.3

Viruses

have

Vacuole

Cell

genetic

membrane material

protein

40

enclosed

capsule.

in

a

Figure

3.2.2

The

cell

structure

of

a

mould

fungus

Cell

wall

Viruses

All

viruses

are

parasites

of

cells

of

organisms.

They

are

thought

to

EXAM have

developed

composed

of

from

genetic

cells,

but

material

now

all

they

have

(DNA

or

RNA)

is

a

central

surrounded

by

a

protein

It coat

or

capsule.

Some

of

them

are

enveloped

in

cell

TIP

core

membrane

is

diffi cult

remem ber their

host

cell

(Figure

Protists

(suc other

microbes,

protists

have

a

cell

structure,

h

fung i,

as

similar

to

that

nuclei.

of

Some

plants

and

protists

are

animals;

more

for

example,

animal-like,

their

such

as

3.2.4);

others,

such

as

Euglena

(Figure

3.2.5),

Not

all

protists

are

small

unicellular

organisms;

are

more

some

are

grow

organisms.

up

to

50

Seaweeds,

metres

long,

including

are

the

classified

as

large

kelps,

which

protists.

DID

and

with

see

into

YOU

five

and

the

contain

either Amoeba

uses

Figure

3.2.5

Euglena

uses

called

pseudopodia

movement

feeding.

KEY

1

Note

algae

inside

food

they

digested

for

places

and

green

where

flagellum

light

the

(×

to

there

is

classify

organisms

fungi,

kingdoms:

animals,

protists.

The

organisms

unicellular ,

Euglena,

bodies

plants

protists

that

e.g.

are

Amoeba

made

or

of

have

simple

many

cells.

photosynthesis

400).

trapped

vacuoles

are

(×

60).

Bacteria

are

unicellular

without

organelles,

with

cell

walls

and

cytoplasm

but

Fungal

cells

have

such

cell

as

walls,

but

no

nuclei,

large

vacuoles

and Make

a

table

do

enclosed

not

in

a

have

cells.

protein

They

are

made

of

genetic

and

material

protists,

others,

large.

such

as

such

of

compare

bacteria,

the

fungi

viruses.

coat. 2

Some

to

chloroplasts. structure

Viruses

QUESTIONS

nuclei.

1

4

crosse s

1.

POINTS

mitochondria,

3

and

KNOW?

SUMMARY

2

compl e te

reach

where

for

then

ticks

all

they

its

and extensions

show

that

different

bacteria,

3.2.4

to

ques tion

Biologists

Figure

table

large

– may

a

featu res

plant-

it multicellular

and

viruse s.

cells

have like.

and

Amoeba

the (Figure

pro tis ts

which

Mak e have

be tw een

Amoe ba

Eugl ena) is

simila rities

differe nces

bacteri a,

the

the

3.2.3).

and

Unlike

to

from

as

Amoeba

seaweeds,

are

and

Euglena,

multicellular

are

and

unicellular;

can

be

very

Distinguish

the

and

between

following

viruses;

fungi;

pairs:

yeasts

bacteria

and

each

of

bacteria

and

mould

protists.

41

3.3

Cells

Animals LEARNING

the

end

should

be

of

this

able

topic

cell

you

–

The

to:

work

a

define

the

terms

tissue,

organ

explain

egg.

continue

cells

the

retain

stem

with

to

multicellular

bodies

This

cell

grow

the

divides

and

ability

to

to

divide

carry

organisms

made

of

produce

to

on

form

a

develop

many

a

two-celled

much

dividing

from

larger

throughout

a

cells

single

embryo.

structure.

life:

cells

(see

11.2).

Other

cells

lose

the

ability

to

these

divide

and

system change

•

multicellular

Most

organ are

and

are

together .

fertilised

cells

Some •

plants

bodies

OUTCOMES that

At

and

make

what

is

meant

by

in

structure

to

become

specialised

for

certain

functions.

cell

specialisation

Specialised •

list

some

examples

specialised

and

cells

in

To

animals

function

out

plants

certain

divided •

explain

being

the

cells

of

advantages

efficiently

we

functions.

between

have

This

different

cells

means

that

that

groups

of

are

the

specialised

functions

of

to

the

carry

body

are

cells.

of

multicellular. Animal

cells

Epithelial

cells

are

found

on

the

surfaces

of

organisms,

for

example

Nucleus

forming

the

outer

layer

of

our

skin.

They

also

line

internal

structures,

Cell

such

as

the

windpipe

and

lungs.

T wo

are

described

here:

ciliated

membrane

epithelial

Ciliated

cells

and

reproductive

on

their

In

to

from

Cytoplasm

to

the

lungs,

the

Ciliated

cells

the

from

windpipe

squamous

the

cells

layer

and

cells

from

of

3.3.1).

back

in

the

air

fallopian

These

and

passages

tubes

cells

forth

to

in

have

in

the

tiny

create

a

the

lungs

female

hair-like

current

in

cilia

the

move

and

ovary

surfaces.

to

the

throat.

the

mucus

In

the

that

traps

fallopian

dust

tubes,

and

cilia

pathogens

move

the

egg

uterus.

the

like

form

lining

impulses

the

(Figure

The

cells

one

cells

line

are

of

the

very

tiny

blood

air

thin

cells.

pockets

in

They

the

form

lungs.

the

outer

Squamous

vessels.

Nerve

cells

in

the

specialised

spinal

animal

cord

which

are

visible

that

and

Plant

cells

cells

(×

70).

3.3.2,

many

have

very

distances

of

have

in

long

the

short

these

in

processes

body.

processes

the

brain

that

Some

that

and

transmit

nerve

cells,

connect

the

spinal

nerves

cord

are

move

are

far

in

the

have

a

our

often

fewer

gut

and

single

skeleton

called

types

other

nucleus

are

muscle

of

places

(Figure

different.

fibres

specialised

in

They

rather

cells

the

body

3.3.4).

each

than

in

The

are

have

muscle

plants

long

‘cells’

than

in

thin

the

many

cells

in

cells.

in

Epidermal

cells

form

the

tissue

that

surrounds

leaves.

four

The these

cells

each

nuclei

There

are

cells)

great

Figure

There

muscle

animals. nuclei

in

(nerve

over

3.3.3).

muscles

The

the

and

neurones

together.

are

epithelial

skin

alveoli

nerve

42

beat

the

the

Most

of

Cilia

found

in

cells.

Nucleus

human

3.3.2

are

and

(Figure

cell

cilia

nose

Squamous

Figure

system

surfaces.

next

the

up

3.3.1

cells

bronchi)

epithelial

membrane

fluid

Fig

squamous

epithelial

(windpipe

Cell

and

guard

cells

that

open

and

close

the

stomata

are

specialised

epidermal

cells.

Root

hair

cells

that

absorb

water

and

mineral

ions Cell

are

also

Some

cell

cells

wall

easy

do

epidermal

to

not

They

become

as

they

develop

are

used

specialised

develop;

transport

water

thick

for

membrane

cells.

they

from

cell

the

for

transport.

also

lose

roots

walls

to

and

transport

of

cell

leaves

retain

a

Xylem

their

(see

some

solution

cells

gain

contents

6.6).

of

rich

a

thick

make

Phloem

their

in

to

it

cells

contents.

sucrose,

amino Nucleus

acids

and

and

other

fruits

solutes.

(Figure

This

fluid

moves

from

leaves

to

roots,

flowers

3.3.5).

Cytoplasm

Organisation

Most

of

specialised

similar

Ciliated

cells

function

dirt

or

the

are

to

trachea

is

an

organs:

root,

trachea

organ

one

stem

or

and

of

more

for

The

of

idea

that

body.

Most

of

and

of

the

major

through

labour.

tissue

the

of

cells

Cells

there

leaf.

Any

of

A

the

is

a

Figure

3.3.4

Muscle

on

need

other

and

take

conditions,

can

work

cells

and

away

such

as

trachea.

carrying

leading

in

An

the

make

muscle

secrete

organ

for

is

a

body.

structure

the

any

Their

bacteria,

up

tissue,

mucus.

group

Plants

in

the

a

some

The

of

of

tissues

have

plant

whole

is

exchange

that

In

work

the

transpiration

certain

for

for

sucrose

out

efficient

one

is

tissues

their

to

waste

(see

Figure

provide

the

products.

and

0.2.3

pH,

on

like

this

the

reproductive

The

page

the

trachea

and

in

arteries

the

and

veins.

6.6)

of

and

the

known

as

in

the

division

of

the

body

body

that

and

maintains

so

that

3.3.5

Xylem

and

phloem

they

the

SUMMARY

QUESTIONS

cells

9).

1

Define

the

following

terms:

specialised,

organ,

organ

system

POINTS and

Cells

in

multicellular

function

2

of

are

tissue,

1

in

system,

An

multicellular,

KEY

found

6.8).

substances

constant

also

wall

Cells

transport

functioning

function

are

the

gut.

for

transport

(see

(see

functions

the

there

from

three

system.

excretion,

cells

human

a

together

animals,

systems

as

the

walls

gas

body.

are

to

carry

that

coordination,

such

together

that

cartilage,

organs

the

temperature

efficiently

cell

group

Figure

rely

nerve

function.

organs.

up

there

compounds

cells

tissue

major

line

lungs

several

other

make

plants,

specialised

is

three

several

specialise

A

one

that

the

glands

movement,

work

of

functions

these

plant

out

sheets

organ.

functions

in

tissues.

carry

from

one

and

an

lungs

digestion,

translocation

just

comprises

reproduction;

water

is

more

one

and

system

systems

or

3.3.3

in.

example,

blood

one

modification

The

tissue

into

to

thin

away

breathe

example

perform

into

mucus

we

For

tissue,

organised

together

arranged

that

trachea.

are

work

move

Figure

cells

cells

that

epithelial

nervous

that

is

dust

Ciliated

of

cells

of

or

Epithelial

several

cells,

organisms

related

nerve

cells,

are

specialised

for

one

major

2

functions.

muscle

cells,

xylem

cells

division

Name

the

of

specialised

tissues

and

up

human

the

labour

organs

gas

cells,

that

make

exchange

and system.

phloem

cells

are

examples

of

specialised

cells.

3 3

Cells

are

organised

into

tissues;

tissues

are

organised

Make

on organs;

organs

are

organised

into

organ

some

learning

notes

into the

specialised

cells

in

this

systems. section.

on

page

these

See

6

How

to

to

help

Learn

you

1

make

notes.

43

3.4

Transport

across

cell

membranes

Cells LEARNING

cannot

have

At

the

end

should

be

of

this

able

topic

Cell

you

the

to:

to

take

define

the

cell,

but

terms

and

total

isolation

explain

important

why

for

surround

they

are

kept

a

that

from

the

partial

in;

they

their

need

surroundings,

cytoplasm

barrier

others

are

to

and

and

get

rid

keep

they

their

wastes.

everything

movement.

exchanged

of

with

Some

the

inside

useful

surroundings.

diffusion,

active

allow

some

substances

to

enter

but

not

others;

this

is

transport why

and

in

substances

are

Membranes

osmosis

in

membranes

substances

•

exist

OUTCOMES

they

they

are

described

as

differentially

permeable

membranes.

are

cells

Diffusion •

explain

that

special

type

osmosis

of

is

a

Oxygen

diffusion

is

needed

concentration •

explain

how

active

from

by

mitochondria

oxygen

within

for

our

aerobic

cells

is

respiration.

very

low

as

it

The

is

used

up

all

transport

the differs

of

time.

The

concentration

outside

the

cell

in

the

tissue

fluid

is

much

diffusion.

higher.

more

Molecules

pass

movement

their

of

through

is

oxygen

the

diffusion

concentration

Unicellular

oxygen

body

carbon

surface.

surfaces

like

In

the

and

the

gradient,

organisms,

and

move

membrane

such

dioxide

as

into

alveoli

our

cell

are

from

to

high

Amoeba,

large

randomly

the

molecules

across

contrast,

in

about

the

animals

lungs

rely

cell

said

low

on

over

pass

to

time,

out.

move

This

down

concentration.

the

diffusion

membrane

have

(see

and,

than

that

specialised

of

forms

gas

their

exchange

5.9).

Osmosis

The

diffusion

The

movement

solutions

is Figure

3.4.1

These

yeast

placed

has

in

cells

blue

diffused

have

dye

into

the

on

of

water

of

either

diffusion

of

through

water

side

is

of

water

membranes

influenced

the

from

by

membrane

a

place

is

the

known

(Figure

with

a

as

osmosis.

concentration

low

3.4.1).

of

the

Osmosis

concentration

of

been

which

them.

solutes

(dilute

solutes

(more

solution)

to

a

concentrated

place

with

solution)

a

higher

across

a

concentration

differentially

of

permeable

membrane.

Blood

STUDY

proteins

FOCUS

blood

Cellulose

cell

fully

all

substances

them.

no

or

walls

as

freely

will

but

find

throughout

Make

sure

mean

and

44

means

pass

can

others

these

this

you

can

drops

Figure

of

in

a

3.4.2

blood

are

solution

shows

put

of

salts,

what

into

that

means

terms

blood

cells

in

a

concentration

salt

as

B

Red

blood

cells

in

tap

C

Red

blood

cells

in

a

solution

blood

that

has

about

the

plasma

water

used

guide.

what

them

Red

same

salt

they

correctly.

Figure

3.4.2

greater

than

the

solution

with

a

concentration

concentration

of

blood

to

different

through.

A

glucose

happens

three

as

cannot.

know

use

suspended

plasma.

when

pass

study

cells

through

permeable

substances

through,

Y ou

can

called

cells

of

described

pass

Impermeable

Differentially

some

are

permeable

can

substances

consists

of

plasma

and

red

solutions.

In

A,

the

liquid

becomes

cloudy

red.

If

a

small

drop

of

this

liquid

is LINK

examined

shape.

In

cloudy.

under

has

Plant

microscope

are

is

a

no

the

the

cells

cell.

and

osmosis

wall.

is

behave

When

much

the

the

cells

blood

The

when

to

has

has

goes

of

C,

they

is

is

not

put

Amoeba

–

see

is

a

unicellular

protist

3.2.

osmosis

the

moves

because

but

each

that

and

usual

water

by

around

water

water,

their

red,

the

moved

volume

cells

into

have

entered

In

in

animal

put

some

membrane

water

decrease

are

cells

water

water

membrane.

cells

differently

plant

cells

because

permeable

So

burst

and

red

change.

blood

This

differentially

into

the

sudden

red

microscope.

cell

by

a

there

increased

cells

cell

B,

There

a

through

blood

under

red

volume

out

become

they

have

absorb

of

the

crinkly.

a

water

by The solution outside the

osmosis.

wall

The

making

high

vacuole

the

cell

concentration

fills

with

turgid.

of

water

When

solutes,

and

pushes

placed

water

into

leaves

against

a

the

the

solution

cell

by

cell

with

cell is more concentrated

than in the vacuole

a

osmosis

and Water

the

vacuole

shrinks

pulling

the

cytoplasm

and

the

cell

out

away

cells

cell

from

in

to

the

this

cell

cell

state

by

wall.

are

This

is

described

osmosis

when

called

as

they

plasmolysis

flaccid.

have

Water

cell

(Figure

can

contents

passes

membrane

move

with

by

3.4.3);

from

different

of

the

cell

osmosis

Cell

wall

Cell

membrane

concentrations. As cytoplasm is pulled

away from the cell

wall, the cell becomes

Active

Active

a

cell

transport

transport

through

the

is

plasmolysed

the

cell

movement

membrane

of

ions

against

a

or

molecules

in

concentration

or

out

of

Figure

3.4.3

When

with

gradient,

put

a

solutes,

using

energy

released

during

respiration.

Cell

membranes

into

high

plant

and

proteins.

work

to

These

move

ions

carrier

and

proteins

molecules

span

into

the

or

cell

out

of

solution

cells

of

become

have plasmolysed

carrier

a

concentration

like

this.

membrane

cells

by

active

transport.

KEY Active

transport

important

villi

in

from

the

the

in

occurs

nerve

small

soil

in

and

kidney

intestine

by

active

almost

(see

all

cells

5.5).

cells,

and

Root

but

also

as

the

hair

we

will

cells

cells

see

that

absorb

it

line

POINTS

is

the

mineral

1

ions

Substances

out

uptake.

QUESTIONS

definitions

concentration

of

the

following

gradient,

terms:

and

active

active

the

molecules

differentially

Make

a

table

diffusion,

column

to

to

show

Explain

why

it

is

permeable

does

not

the

and

the

similarities

active

features

and

transport.

that

you

differences

Remember

are

between

to

include

a

comparing.

of

molecules

water

solution

with

Describe

how

important

that

the

concentration

of

the

become

too

low

or

too

active

transport

occurs

to

a

with

high

a

solutes

from

low

solutes

to

a

solution

concentration

(concentrated

across

a

differentially

blood membrane.

high.

move

a

molecule

Active

transport

is

the

out of

molecules

and

cell. ions

5

of

solution)

movement of

a

(dilute

of

4 4

diffusion

membrane,

permeable plasma

gradient.

is

solution) 3

a

transport

show

osmosis

movement

Osmosis

concentration

2

transport.

down

the

and

diffusion,

a osmosis

is

into

diffusion,

concentration

3 Write

move

by

and

Diffusion

of

1

cells

osmosis

2

SUMMARY

of

Make

a

spider

membranes.

yourself

diagram

(See

about

How

how

to

to

summarise

to

Learn

do

this.)

2,

on

movement

page

8

to

across

remind

cell

across

against

a

gradient

a

cell

membrane

concentration

using

energy

from

respiration.

45

Unit

SECTION

1

3

1:

Practice

Multiple-choice

Chloroplasts

in

a

palisade

exam

questions

questions

mesophyll

cell

are

in

5

Which

of

the

following

is

an

following

is

a

organ?

the

A

cytoplasm

B

nucleus

C

sap

D

space

A

blood

B

epidermis

C

kidney

D

xylem

vacuole

between

the

cell

wall

and

the

cell 6

Which

of

the

membrane

2

Which

to

3

occur

must

between

a

be

cell

present

and

A

cell

wall

and

cell

B

cell

wall

and

cytoplasm

C

cytoplasm

D

vacuole

The

table

and

and

cell

shows

the

microbes.

A,

or

D,

C

A

a

bacterium

B

Amoeba

C

a

D

yeast

osmosis

surroundings?

mould

membrane

wall

of

B,

its

for

membrane

cell

groups

in

4

structures

components

Which

indicates

the

of

of

the

four

following,

components

found

bacteria?

Cell

Cell

membrane

wall

Nucleus

Chloroplast

Mitochondrion

A

✓

✗

✓

✗

✓

B

✓

✓

✓

✓

✓

C

✓

✓

✗

✗

✗

D

✓

✓

✓

✗

✓

Substances

transport,

the

cross

cell

diffusion

correct

membranes

and

examples

of

osmosis.

each

of

by

active

Which

these

shows

three

processes?

Active

A

transport

Glucose

by

epithelium

small

B

Mineral

of

root

Osmosis

ions

hair

by

Carbon

cells

red

dioxide

blood

ions

hair

by

cells

Oxygen

by

epithelium

Water

of

in

by

pond

Amoeba

water

alveolus

C

Oxygen

blood

by

red

cells

Carbon

red

dioxide

blood

cells

by

Glucose

Water

in

46

by

pond

Amoeba

water

Mineral

root

ions

hair

by

cells

by

epithelium

small

D

by

cell

intestine

Mineral

root

Diffusion

of

intestine

Oxygen

blood

by

cells

red

fungus

protist?

SECTION

7

2:

Visking

Short

tubing

membrane

Some



Six

in

is

similar

that

students

pieces

answer

of

it

is

questions

to

cell

surface

differentially

followed

Visking

this

e

Predict

permeable.

of

procedure.

tubing

in

length

were

make

a

bag.

Five

tied

bags

at

one

concentrations

were

of

students

filled

peeling

they

weighed

10.0 g.

a

sugar

with

distilled

water

The

bags

were

suspended

in

tied

a

with

large

The

sixth

bag

After

6

blotted

hours,

dry

the

with

of

the

cotton

beaker

bags

paper

of

were

small

onions

The

are

investigation

They

divided

the

into

five

batches

same

Each

of

batch

10

was

onions

placed

solution

of

different

concentrations

of

into

salt

mass.

thread

and

distilled

each

water .

The

chloride).

batch

was

students

mass.

The

After

immersion

surface

dried

calculated

table

the

shows

and

for

two

percentage

their

hours

reweighed.

change

results.

removed,

towels

results

hours.

(3)

their

onions.

them.

and Concentration

reweighed.

mass

18

was

in 

the

prediction.

continued

50

weighed

(sodium



to

another

solution

a

filled

for

with

and

until

your

happen

left

end

peeled

different

will

if

measuring

by

to

what

bags

Explain

The

140 mm

the

shown

in

Figure

Mean

mass

of

onions/g

Percentage

–3

1.

of

salt

/

g dm

change before

after

in

2

mass immersion

hours

22

immersion

0

147

173

+18.0

25

153

165

+8.0

50

176

172

−2.0

100

154

149

150

149

142

−4.5

200

183

175

−4.5

20

g/sruoh

18

6 retfa

16

ssaM

14

Information

and

data

used

to

compile

the

table

from

Practical

12 osmosis

in

Education

vegetable

(1993)

27

pickling,

(2),

Ray

pages

W

James.

Journal

of

Biological

90–91

10

0

50

100

150

200

250

f

300

i

Concentration

of

Calculate

in

–3

sugar/g dm

mass

the

for

percentage

the

onions

change

kept

in

the

–3

100 g dm Figure

salt

solution.

Show

your

1

working.

a

Explain

why

the

ii

i

included

a

bag

that

contained

distilled

water

surface-dried

Make

Figure

c

a

the

bags

before

weighing

table

to

record

the

data

shown

(4)

the

results

of

the

the

One

student

that

they

how

graph

the

to

calculated

the

mass.

(1)

percentage

change

concentration

of

solution.

iv

Use

in

salt

(5)

your

which

graph

there

to

is

find

no

the

salt

change

in

Total

not

solution

mass. (1)

25

marks

the

results

saying

reliable.

procedure

should

make

the

results

practice

questions

be examples

can

be

found

more on

reliable.

of

against

and changed

in

(5)

criticised

were

a

mass

Further State

students

change

students’

investigation.

d

in

Draw

in

(1)

1.

Explain

why

(2)

them.

b

State

percentage

iii

ii

(2)

students

the

accompanying

CD.

(1)

47

4

Nutrition

4.1

T ypes

Producers LEARNING

At

the

end

should

be

define

of

this

able

the

nutrition,

nutrition

topic

Y ou

will

and

food

terms

autotrophic

these

into

heterotrophic

and

the

three

webs

and

give

from

show

chemical

compounds

saprophytic

complex

differences

types

of

chains

examples

of

and

energy.

(carbon

organic

autotrophic

1.4

and

feeding

1.5

that

we

can

relationships.

write

food

Producers,

chains

such

as

green

(Figure

webs.

These

and

compounds.

type

the

at

base

energy

absorb

and

of

the

light

also

water)

The

and

are

convert

organisms

dioxide

nutrition

4.1.2),

They

use

simple

them

nutrition

organisms

that

of

almost

from

to

used

feed

the

all

Sun

inorganic

make

by

producers

this

way

are

between

autotrophs.

Consumers

are

not

able

to

utilise

simple

inorganic

nutrition

compounds •

to

phytoplankton

food

called the

remember

to:

is state

consumers

you

nutrition

•

and

nutrition

OUTCOMES

plants

•

of

each

type

or

absorb

and

make

use

of

light

energy.

Instead

they

feed

of on

other

organisms.

This

type

of

nutrition

is

heterotrophic

nutrition

nutrition. and

organisms

that

Autotrophic

Autotrophic

simple

and

hydrogen

make

the

means

a

are

and

are

larger

iron

and

raw

as

Figure

4.1.1

Mangrove

all

green

trees,

plants,

called

eat

the

in

solid

the

the

are

of

food

ocean,

48

like

need

elements

major

phosphorus.

about

other

are

elements

elements,

such

these

Carbon

elements

dioxide

carbon,

elements

absorbed

required

These

as

only

are

by

green

required

magnesium,

elements

in

in

sulfur,

4.5.

food

in

a

variety

into

food

of

way.

Protists,

vacuoles.

This

such

as

process

(see

of

(see

3.2

their

the

it

is

food

body

like

this

6.4).

Multicellular

using

and

(see

suck

6.8)

jaws

and

body

and

animals

is

teeth.

fluids.

Fluid

Aphids

mosquitoes

that

feeders

feed

feed

on

from

blood

10.2).

supported

the

and

dead

The

by

fruiting

an

wood.

digested.

bodies

extensive

These

The

of

hyphae

hyphae

mushrooms

network

then

of

release

absorb

in

hyphae

that

enzymes

the

onto

products

feed

of

and

in

a

variety

their

use

hosts.

of

ways.

Lice,

piercing

Some

ticks

and

mouthparts

parasitic

fleas

to

animals

hold

suck

onto

blood.

live

the

on

body

Many

of

parasitic

the

the

live

gut

inside

or

on

the

bodies

nutrients

of

that

their

are

hosts

feeding

transported

in

on

the

digested

blood.

food

There

planktonic

these.

to

from

are

in

algae

more

heterotrophic.

are

where

host

animals autotrophs

way

all

surface

their

microscopic

and

with

the

need

digestion.

the

open

is

other

three

particles

into

plants

through

Parasites

the

bite

of

4.1.5

spreads

main

their

food

surface

same

Figure

the

food

phloem

Fungi

In

The

environment.

provide

autotrophs

These

organisms

nutrition

phagocytosis

pierce

4.1.2

heterotrophs

like

are

autotrophic.

Figure

gain

engulf

called

their

that

addition

potassium

There

Heterotrophic

Amoeba,

in

compared

calcium.

Heterotrophs

are

Autotrophic

from

materials

ions.

nitrogen,

quantities

way

feeding’.

substances.

surroundings

plants

‘self

oxygen;

of

this

substances

the

range

in

nutrition

inorganic

water

feed

are

some

parasitic

fungi

that

live

on

human

skin;

ringworm

is

an

example.

animals;

typhoid

There

are

examples

and

than

bacteria

on

living

species

affect

tuberculosis

Saprophytic

Many

many

that

us

(TB)

of

bacteria

are

(see

the

that

bacteria

are

parasites

that

cause

of

cholera,

10.1).

nutrition

and

fungi

feed

organisms.

on

Earlier

dead

we

and

decaying

considered

matter

these

rather

organisms

Figure

as

decomposers

because

they

break

down

the

dead

remains

4.1.3

Animals

cattle,

plants

and

animals

and

help

to

recycle

elements,

such

as

nitrogen.

This

is

a

form

of

heterotrophic

nutrition

because

guts

the

source

and

such

as

them,

T able

carbon

then

fungi

the

absorbing

that

world

4.1.1

compounds

grow

would

summarises

the

on

be

by

soluble

dead

full

the

secreting

of

products.

wood,

dead

enzymes

can

but

differences

not

onto

Many

digest

their

these

that

termites

contain

food

microbes

digest

their

that

help

food.

decomposers,

cellulose.

decomposed

between

sheep,

and

they many

obtain

as

horses

carbon have

and

such

of

three

Without

trees.

types

of

nutrition.

T able

4.1.1

Types

of

nutrition

Figure

Feature

T ypes

of

4.1.4

This

nutrition

Autotrophic

the

Heterotrophic

boy

has

ringworm

of

scalp.

Saprophytic

(saprotrophic)

Source

of

Light

Complex

energy

Source

e.g.

of

Carbon

dioxide

Complex

carbon

Types

(as

of

All

organism

green

plants;

fat,

compounds

protein,

compounds

of

carbon,

cellulose

of

carbon

above)

Animals;

algae;

carbon

starch,

fungi

parasitic

Decomposers

and

–

many

Figure

4.1.5

species

These

mushrooms

Costa

Rican

millions

some

bacteria

bacteria;

plants,

parasitic

of

e.g.

bacteria

YOU

Scientists

4000 m

have

in

the

found

base

of

the

communities

Cayman

penetrates

to

food

T rench

these

webs

organisms

between

depths,

obtain

of

so

their

the

Jamaica

at

depths

and

autotrophic

energy

from

Cuba.

of

Draw

a

spider

show

the

at

using

sulfur

and

hydrogen

sulfide

released

floor

known

as

hydrothermal

include

organisms

the

type

of

from

holes

Make

each

a

table

involves

the

conversion

of

compounds

(carbon

dioxide

and

compounds.

The

energy

for

this

water)

comes

to

Heterotrophic

nutrition

involves

Name

from

Saprophytic

involves

matter.

nutrition

feeding

on

is

a

form

organic

the

levels

Give

feeding

on

of

organic

heterotrophic

material

from

dead

a

type

and

of

examples

level

from

in

your

locality.

the

type

of

of

the

compounds.

nutrition

and

special

between

sheep

light. the

their

a 3

show

complex

and

2

to

trophic

relationship organic

each

simple 3

inorganic

to

trophic

each

wildlife

nutrition

show

vents.

POINTS

Autotrophic

of

in

nutrition.

1

that

types

named

chemical

assign

KEY

to

nutrition.

different sea

diagram

different

nutrition;

No

bacteria

simple

over

2

the

QUESTIONS

1.6)

KNOW?

light

reactions

spores.

fungi

(see

1 DID

tiny

a

release

and

SUMMARY dodder

of

in

forest

bacteria

stomachs

that

(see

live

1.6

in

for

hint).

that

decaying

4

Suggest

fungi

why

saprophytic

produce

many

spores.

49

4.2

Photosynthesis

LEARNING

At

the

end

should

be

Water

weeds

rivers.

During

oxygenate

of

this

able

topic

in

you

oxygen

–

daylight

the

define

the

state

the

the

raw

reactions

term

and

source

of

materials

products

of

energy,

and

write

word

product

of

in

is

which

a

process

carbon

only

is

in

absorbed

by

that

and

ponds,

of

lakes

gas

and

that

(Figure

are

rich

4.2.1).

light

energy

water

are

to

drive

changed

chemical

to

glucose

a

green

pigment

which

is

found

chloroplasts.

process

is

summarised

in

this

role

word

equation:

balanced

equations

the

uses

and

chlorophyll,

energy

for dioxide

+

water

glucose

photosynthesis

state

tanks,

bubbles

photosynthesis

carbon

•

fish

photosynthesis

dioxide

light

chemical

in

release

oxygen.

Light

the

The

•

they

to:

photosynthesis

•

water

hours

waste

Photosynthesis

•

the

OUTCOMES

+

oxygen

chlorophyll

of

chlorophyll

in The

chemical

equation

for

photosynthesis

is:

photosynthesis

light

•

describe

the

fate

of

the

6CO

+

6H

2

products

of

the

process

used

The

to

The

• bright

sunshine

freshwater

releases

in

plant,

bubbles

as

should

learn

these

realise

many

used

Elodea,

of

gas

rich

and

in

two

in

gains

from

A

cellulose

to

reactions

chloroplasts.

reactions

50

a

the

in

for

to

a

dioxide

light

to

These

simple

ions

energy

plant.

water

water

and

to

diffuse

form

electrons

are

sugar.

photosynthesis

the

and

split

Some

is

used

is

to

produce

respired

needed

to

keep

the

produce

to

make:

a

immediately

cells

alive.

the

this

is

glucose

they

transported

and

fleshy

around

dispersal

(see

fruits

6.8,

to

the

plant

9.5

attract

in

the

and

animals

phloem.

for

It

is

pollination

9.6)

storage

organs,

(e.g.

Irish

such

as

seeds,

potatoes),

as

a

swollen

roots

long-term

(e.g.

energy

yams),

store

splitting

gains

help

leaves

to

to

make

seeds

store

cell

energy

walls,

disperse

in

for

also

the

use

used

in

to

respiration

make

fibres

at

in

night

cotton

bolls

wind

that lipids

to

make

cell

membranes

and

for

energy

storage,

e.g.

in

seeds.

In

combining

where

acids

sugars

and

with

then

use

nitrogen

them

to

from

make

nitrate

ions,

proteins,

plants

such

as

These

of

a

electrons

reduction

in

can

make

carbon

electrons.

the

reaction

substance

called

2

glucose

stems

•

they

(see

water.

–

starch

amino

come

of

use

seed

starch

By these

dioxide

provides

oxygen.

dioxide

produced

carbon

absorbs

and

substances

nectar

•

•

within

of

6O

oxygen.

but

summarise

one

+ 6

FOCUS

equations,

occur

it

plants

sucrose

of

Chlorophyll

carbon

sugar

fate

swollen

You

O 12

the

•

STUDY

photosynthesis,

electrons

reduce

range

cells

The

ions,

simple

wide

by

of

chloroplasts.

hydrogen

In

H 6

chlorophyll

into

4.2.1

C

2

photosynthesis.

In

Figure

energy

O

is

reaction.

5.3)

and

carrier

proteins

in

cell

membranes

(see

3.4).

enzymes

Gas

exchange

in

plants STUDY

Plants

use

the

oxygen

they

make

for

their

own

aerobic

respiration Using

(see

5.8).

However ,

they

cannot

use

all

of

it

and

much

diffuses

leaves

into

the

atmosphere

for

other

organisms,

like

us,

to

bullet

use.

to

the

day

carbon

dioxide

diffuses

into

leaves

through

make

stomata

diffuses

out.

At

night,

photosynthesis

cannot

occur

as

there

light.

some

and

Most

remain

some

stomata

partially

carbon

tend

open

dioxide

to

to

to

close

allow

diffuse

at

night

some

out.

to

conserve

oxygen

Much

to

more

water ,

diffuse

Y ou

Uptake

during

the

day

than

is

produced

at

night

(Figure

good

can

also

put

the

same

into

chart

spider

diagrams

diagrams.

T ry

but

into

carbon

flow

converting

the

information

the

glucose

on

leaves

dioxide

fate

of

into

a

diagram

is (see

absorbed

a

is or

no

is

learning

and information

oxygen

your

So notes.

during

points

out way

of

FOCUS

question

3).

4.2.2).

of

carbon

dioxide

No

net

uptake

or Release

release

of

SUMMARY

QUESTIONS

carbon

dioxide

1

a

Write

out

chemical

the

balanced

equation

for

photosynthesis. 00.00

06.00

12.00

18.00

24.00

b

Annotate

the

equation

Time/h

by Figure

4.2.2

The

uptake

and

release

of

carbon

dioxide

from

a

plant

during

identifying

materials, hours

on

a

very

bright

sunny

on graph

because

it

shows

is

that

respiring

at

night,

and

not

the

plant

releases

carbon

over

the

next

hour

the

photosynthesising.

light

intensity

The

increases

sun

and

rises

so

of

photosynthesis.

At

08.00,

the

in

respiration

for

its

plant

uses

all

the

photosynthesis

and

carbon

does

from

the

air .

higher

Between

than

the

09.00

rate

of

and

11.00

the

respiration

so

rate

the

of

equation.

not

the

role

of

chlorophyll

photosynthesis.

dioxide

Make

a

spider

diagram

to

absorb

what

happens

to

photosynthesis

the becomes

the

Explain

show any

of

products

the

3 produced

source

the

at

does

in

rate

the

and

dioxide

2

07.00;

raw

day.

energy

The

the

24

plant

absorbs

glucose

produced

in

more

photosynthesis. carbon

dioxide

from

the

air .

4

KEY

Make

POINTS

occur

1

Photosynthesis

to

2

sugars

is

using

Photosynthesis

the

light

conversion

as

occurs

a

in

of

carbon

of

energy.

source

dioxide

and

water

and

Chlorophyll

is

the

green

chloroplasts.

pigment

in

5

The

for

chloroplasts

that

the

that

mitochondria

during

the

the

occurs

gas

exchange

between

leaves

absorbs

sugar

produced

storage,

is

sucrose

combined

used

to

make

in

photosynthesis

for

with

transport

nitrogen

and

to

is

converted

cellulose

make

for

amino

to

cell

acids

starch

the

atmosphere

During

the

stomata

day

and

day,

Explain

walls.

and

your

reference

a

during

which

and

to

b

at

night.

answers

by

photosynthesis

respiration.

proteins. 6

5

show

energy.

Some

are

to

substances

between

Describe

the

4

of

day

and light

diagram

chloroplasts

that 3

a

exchanges

carbon

oxygen

dioxide

diffuses

diffuses

out;

at

into

night

leaves

the

through

reverse

happens.

Discuss

the

importance

photosynthesis

for

life

of

on

Earth.

51

4.3

Leaf

Leaves LEARNING

the

end

should

•

be

describe

of

this

able

the

topic

leaf

you

to:

external

that

a

typical

describe

of

a

organs

midrib

the

main

which

vein

all

is

adapted

green

for

the

leaf

to

contains

over

the

with

the

the

a

photosynthesis.

large

stem.

main

thin

part

A

surface.

Extending

vein.

of

flat

typical

Minor

the

leaf

The

leaf,

from

veins

known

petiole

the

branch

as

or

petiole

the

is

from

blade

structure 4.3.1).

leaf

the

typical

hibiscus,

attaches

the

Some •

of

stalk

(Figure

of

plant

OUTCOMES like

At

are

structure

internal

leaf

as

of

the

external

features

are

adaptations

for

photosynthesis:

structure

seen

in

•

green

to

absorb

•

large

surface

•

veins

–

light

–

the

green

colour

is

chlorophyll

cross-section

•

explain

how

adapted

for

leaves

•

If

to

carry

–

and

oxygen

you

as

so

tear

viewed

two

to

water

blade

hibiscus

and

petiole

of

a

the

there

the

absorb

as

much

light

as

possible

and

ions

throughout

the

leaf

and

carry

When

are

a

cells

are

typical

short

of

Figure

light

scattered

allow

They

is

leaf

blade

with

guard

Stomata

leaf.

of

epidermis.

stomata

The

out

thin

lower

4.3.1

–

photosynthesis. sucrose

Figure

area

are

some

leaves

4.3.2

that

microscope.

control

to

another

the

the

diffuse

cut

in

distances

is

You

lower

can

for

of

the

out

to

peel

that

Each

hole

of

carbon

the

the

of

there

a

are

stoma

in

air

dioxide

off

epidermis

see

epidermis.

and

for

possible

the

width

in

adaptation

are

it

shows

throughout

gases

leaves

diffusion

leaf

many

consists

between

spaces

them.

inside

the

photosynthesis.

cross-section

and

studied

under

a

leaf.

microscope,

they

Figure

is

same

4.3.4

have

drawn

the

from

appearance

a

section

of

the

through

leaf

in

Figure

another

leaf

4.3.3.

from

the

plant.

Cuticle

Upper

epidermis

Chloroplast Palisade

mesophyll

Figure

4.3.2

Carbon

diffuse

dioxide

and

through

stomata

(×

oxygen

Air

space

these

200).

Vascular

bundle

(xylem

and

Spongy phloem) mesophyll

Lower

Figure

4.3.3

A

cross-section

of

a

see

leaf

blade.

large

spaces,

a

of

the

You

can

intercellular

stoma

and

epidermis

edge

air

a

Sub-stomatal

air

space

Figure (×

52

100).

Guard

cell

Stoma

vein

4.3.4

This

drawing

shows

the

tissues

inside

the

blade

of

a

leaf.

of

T able

in

4.3.1

Figures

T able

summarises

4.3.3

4.3.1

and

Functions

Tissue

Function

Upper

Cells

epidermis

vapour

are

the

of

make

to

the

a

tissues

waxy

the

air

transparent

mesophyll;

Palisade

Cells

mesophyll

the

to

functions

of

the

tissues

that

you

can

see

4.3.4.

contain

cells

are

capture

pushes

allow

many

Cells

mesophyll

mesophyll

to

throughout

Xylem

Supplies

Phloem

Phloem

by

water

light

to

light

to

as

the

pass

loss

through

to

the

much

the

large

light;

vacuole

each

cell

spaces

than

in

carbon

below)

chloroplasts

of

of

water

cells

epidermis

absorb

allow

possible;

diffusion

of

epidermal

lower

to

to

edge

air

the

and

(see

together

larger

allow

the

reduces

cuticle

chloroplasts

much

separated

that

stomata

chloroplasts

Spongy

leaf

6.7);

have

packed

as

a

cuticle

(see

to

may

in

palisade

dioxide

leaf

and

transports

ions

sucrose

away

from

the

leaf

to

other Figure

parts

of

the

4.3.5

This

plant

of

electron

the

inside

shows

Lower

Cells

are

like

those

of

the

upper

epidermis;

some

specialised

as

pairs

of

guard

cells

that

control

cylindrical

oxygen

Some

of

the

of

stomata

diffuse

internal

in

features

through

and

are

out

which

and

carbon

water

adaptations

dioxide

vapour

for

and

diffuses

close

leaf

packed

–

to

palisade

maximise

mesophyll

absorption

cells

of

light

near

the

where

the

stomata

diffuse

•

thin

–

(usually

into

the

short

atmosphere

in

lower

leaf

(and

distance

to

the

for

cells

epidermis)

oxygen

to

diffusion

of

the

to

upper

its

allow

diffuse

of

surface

intensity

is

of

palisade

and

cells

shape

of

leaf

is

a

air

(×

very

and

extensive

spaces

inside

200).

carbon

QUESTIONS

the

highest

dioxide

to

Make

a

large

hibiscus

out)

carbon

in

photosynthesis:

1

•

there

system

out.

SUMMARY

•

leaf

the that

aperture

a

palisade

are are

epidermis

that

micrograph

of

leaf

Annotate

dioxide

spongy

from

to

the

show

features

mesophyll

drawing

in

your

how

are

Figure

of

the

4.3.1.

drawing

the

external

adaptations

for

photosynthesis. •

large

the

intercellular

mesophyll

•

xylem

to

•

phloem

air

spaces

–

for

diffusion

of

carbon

dioxide

to

all

cells

bring

2

water

and

Make

ions

each to

transport

sucrose

to

the

rest

of

the

diagram

of

to

tissue

of

leaf,

with

Annotate

show

how

a

cross-

showing

two

or

three

your

the

diagram

internal

POINTS

structure

1

a

plant. cells.

KEY

a

section

Leaves

are

the

site

are

green

of

most

photosynthesis

that

takes

place

for

in

of

a

leaf

is

adapted

photosynthesis.

plants. 3

2

Leaves

energy;

they

absorption

for

3

Internally,

cells

of

carbon

of

leaves

closely

light

have

and

diffusion

and

as

they

are

large

contain

large

are

carbon

packed

dioxide

a

they

surface

thin

the

the

that

to

absorb

maximise

there

are

vein,

light

short

for

air

State

photosynthesis

layer

spaces

atmosphere

to

for

to

all

by

allow

the

many

absorption

diffusion

mesophyll

of

cells.

4

functions

in

cells

of

leaves:

palisade

guard

distances

having

maximum

the

following

light

air

palisade

intercellular

from

area

to

dioxide.

adapted

in

so

chlorophyll

the

epidermis,

mesophyll,

and

intercellular

spaces.

Use

Figure

diagram

section

to

4.3.5

to

show

through

a

draw

a

horizontal

the

palisade

mesophyll.

53

4.4

Investigating

photosynthesis

T esting LEARNING

Testing At

the

end

leaves

for

of

this

topic

leaves

for

starch

be

able

describe

solution

how

to

presence

•

describe

to

test

of

use

of

iodine

leaves

for

if

the

to

you

and

into

The

simply

decolourised

starch

how

starch.

show

chlorophyll

starch.

colour

put

by

•

explain

for

what

destarched

Put

outline

the

is

meant

by

of

temperature

dioxide

a

leaf

2

If

to

you

of

3

Put

the

the

and

intensity,

a

removing

boiling

so

you

Bunsen

leaf

4

Stand

concentration

on

into

the

5

Remove

test

and

a

a

plant

has

been

photosynthesis

is

is

used

iodine

a

leaf.

to

detect

solution

The

the

cannot

leaves

must

presence

be

seen

first

be

chlorophyll.

water

for

extract

one

the

minute.

This

destroys

chlorophyll.

burner

to

boil

the

water ,

turn

it

off

afterwards.

tube

of

ethanol.

The

chlorophyll

dissolves

tube

in

a

beaker

of

hot

water

for

about

10

minutes.

the

leaf

rehydrates

in

the

cold

leaf

water.

which

This

removes

softens

it

and

the

makes

it

photosynthesis.

to

spread

Spread

the

eye

protection

Safety:

ethanol

is

flammable

If

out.

leaf

on

out

flat

water

If

leaf

you

for

goes

test

Is

Turn

off

Bunsen

a

about

a

has

plant

used

a

white

to

Follow

leaf

is

there

from

week

you

a

surface

light

needed

these

and

put

iodine

is

for

starch

in

to

is

it

present.

If

it

stays

in

a

dark

a

light

starch.

that

has

has

sugars

Plants

instructions

of

no

find

converted

that

starch

is

plant

will

destarched.

show

light

blue-black,

colour

been

production

Iodine

on

it.

the

The

that

been

no

starch

and

have

necessary

for

in

used

in

been

it.

place

All

of

the

respiration.

destarched

are

photosynthesis.

photosynthesis?

to

show

that

light

is

needed

for

the

photosynthesis.

solution

1

T ake

tin

a

destarched

foil

or

black

plant

and

paper

to

attach

it

cover

prevent

part

light

of

a

leaf

getting

with

some

through.

be

Make

sure

you

firmly

using

tape

or

paper

clips.

not

burn

yourself

Figure

4.4.1

Testing

a

leaf

for

2

Leave

3

Test

the

the

plant

leaf

for

in

the

starch

light

as

in

for

a

few

Figure

hours.

4.4.1.

starch

STUDY

The

FOCUS

results

present

or

therefore

54

on

the

can

test

wash

and

starch

to

in

the

Ethanol

careful

solution

with

solution

yellow-brown

Safety:

that

ethanol.

solution

Boiling

show

carbon

6

wear

to

produced

investigate

light

easy

Safety:

Iodine

change

the

into

use

ethanol rate

way

sugar

a

leaf

how

effect

the

photosynthesis

in •

good

are membranes,

necessary

a

of

that 1

light

Some

to: converted

•

is

you photosynthesising.

should

starch

OUTCOMES

from

not;

how

testing

they

do

much

leaves

not

for

tell

us

starch

how

photosynthesis

show

much

took

whether

starch

place.

is

starch

present

is

and

Results:

•

•

Only

the

light

go

The

a

Is

parts

parts

of

the

these

production

a

test

leaf

that

were

left

uncovered

and

received

that

needed

instructions

of

were

covered

did

not

receive

light

and

are

colour.

chlorophyll

T ake

the

leaf

yellow-brown

Follow

1

of

blue-black.

starch

destarched,

in

to

for

photosynthesis?

show

that

chlorophyll

is

needed

for

the

photosynthesis.

variegated

plant

such

as

a

hibiscus

(Figure

4.4.2). Figure

(Variegated

2

the

leaves

the

white

Place

the

means

must

be

parts

plant

of

in

the

leaves

green

the

the

have

and

different

white.

There

colours;

is

no

in

this

chlorophyll

Pick

a

leaf

and

draw

it

for

about

six

Examples

hours.

carefully

to

show

the

distribution

of

of

their

and

green

parts

(or

take

a

Test

this

variegated

drawing

of

the

leaf

results

for

or

starch

take

a

The

much

effect

of

temperature

water

the

weed

rate

of

as

in

Figure

4.4.1

and

make

a

is

light

iodine.

photograph.

light

intensity,

the

in

rate

Figure

carbon

of

2

photosynthesis

dioxide

concentration

photosynthesis

on

page

can

be

59.

can

The

be

three

investigated

by

and

investigated

intensity

to

is

factors

59.

using

for

than

Benedict’s

in

5.1.

that

–

by

putting

a

lamp

at

different

–

by

putting

the

plant

in

beakers

QUESTIONS

affect

1

Explain

why:

changing:

distances

from

Leaves

of

water

at

must

b

different

concentration

hydrogen

carbonate

–

by

adding

(NaHCO

)

to

different

the

quantities

be

when

testing

starch.

Destarched

be

dioxide

first

decolourised

the

used

leaves

when

light

should

finding

is

out

needed

of for

sodium

in

page

leaves

rather

test

whether carbon

shown

on

described

SUMMARY

temperatures

•

test

sugar

This

for

temperature

10

with

plant

•

and

possible

reducing

a

•

9

photosynthesis?

on

as

experiments

are

photograph).

solution

How

leaves

the

It

4

these

results

questions white

hibiscus

LINK

and 3

Variegated

in

leaf.)

light

4.4.2

case

photosynthesis.

water.

3

2

a

Predict

would

the

expect

hibiscus KEY

if

leaves

you

variegated

are

tested

POINTS for

1

result

To

test

first

for

by

starch,

boiling

in

chlorophyll

ethanol

has

and

to

then

be

removed

testing

with

from

leaves

b

starch.

Explain

your

prediction.

iodine 3

In

experiments

to

measure

solution. the

2

A

plant

leaves

kept

and

is

in

the

dark

for

a

week

uses

up

all

the

starch

in

its

intensity

destarched.

The

need

for

light

can

be

on

shown

by

using

destarched

are

partially

covered

with

light-proof

Variegated

leaves

with

green

and

white

parts

are

used

keep

the

5

that

Counting

to

chlorophyll

the

determine

bubbles

the

rate

is

needed

produced

of

for

by

rate

it

is

light

of

important

temperature

Suggest

why

this

so.

to 4

show

the

material. is

4

changing

leaves constant.

that

of

photosynthesis

to 3

effect

Suggest

why

bubbles

is

counting

photosynthesis.

a

water

photosynthesis.

weed

can

be

used

to

a

measure

good

the

way

rate

of

photosynthesis.

55

4.5

Plant

Plants LEARNING

need

mineral

the

end

should

be

of

this

able

topic

mineral

you

need

to:

ions

other

needed •

explain

that

plants

to

nutrients

outline

how

effect

to

of

deficiencies

explain

just

than

and

minerals.

carbon,

These

hydrogen

complex

DNA.

transport

the

(see

on

plant

why

absorption

of

these

many

terms

and

compounds,

called

different

refer

to

oxygen.

such

mineral

as

the

Most

salts,

elements

minerals

amino

acids,

salts,

plants

are

proteins,

Plants

3.4).

absorb

Root

the

hair

mineral

cells

ions

provide

a

they

large

require

surface

by

area

plants

elements

of

mineral

ions.

elements

are

nitrogen

and

magnesium.

Even

though

is

a

huge

quantity

of

nitrogen

in

the

form

of

nitrogen

gas

(N

)

2

growth the

air,

most

plants

are

unable

to

use

it.

The

exceptions

are

the

require flowering

the

make

of

in •

to

sometimes

investigate

there minerals

order

roles

T wo the

in

are

many

for

•

or

nutrients

require

for

active different

These

make

chlorophyll mineral

nutrients

nutrition

OUTCOMES compounds.

At

mineral

nitrogen

plants,

known

as

legumes,

such

as

Pride

of

Barbados

and (Figure

4.5.1).

These

plants

have

root

nodules

full

of

bacteria,

which

magnesium can

•

explain

these

how

plants

obtain

take

acids

elements.

of

nitrate

The

1.6).

ions

roles

Nitrate

xylem.

of

nitrogen

(see

ions

the

and

leaves

Leaves

so

make

of

are

in

new

amino

the

phloem.

4.5.1

Pride

of

Barbados

is

You

can

tell

of

the

the

characteristic

seed

can

you

in

KNOW?

deprive

a

plant

the

of

about

start

a

to

week,

turn

its

can

in

and

the

not

56

for

the

chlorophyll.

energy

when

broken

it

is

to

make

not

It

and

of

leaves

for

rebuild

in

the

Magnesium

trapping

chlorophyll

is

part

light

in

their

magnesium.

sugars

Amino

uses

to

they

acids

them

to

flowers,

produce

are

in

exported

make

root

from

proteins

tips

and

in

areas

seeds.

deficiencies

effects

that

mineral

nutrients

have

on

plants

when

they

are

not

available.

grown

water

or

using

sand

(solution).

nutrients

hydroponics.

and

supplied

Solutions

plants

require

are

This

with

the

is

minerals

prepared,

normally

where

plants

they

containing

(complete

are

require

all

the

solution).

needed

for

plant

growth

are

being

investigated,

When

the

leaves

yellow

synthesised.

stimulus

make

of

is

be

water

as

may

have

different

salts

dissolved

in

it

to

give

all

the

mineral

the nutrients

chlorophyll

the

growth

minerals

water will

form

light the

for

amino

pods.

mineral If

investigate

studying

grown

YOU

to

the

shape

Plants

DID

it

in

plants

responsible

down

the

in

chlorophyll.

is

leaves,

mineral

convert

nitrogen

transported

supply

plant

new

and

this

by by

which

ions.

soil

absorb

a

We legume.

as

are

make

using

The

such

the

to

soil.

ions

to

break

nitrate

in

nutrients

constant

acids

and

Investigating

Figure

a

air

have

the

needed

constantly

growth,

in

molecule,

need

photosynthesis

leaves

water

magnesium

ions

Plants

and

the

plants

mineral

chlorophyll

energy.

from

other

from

of

Both

gas

All

that

plants

require

(control).

More

solutions

are

prepared

down

Light

plant

is

a

one

type

nitrogen

and

without

of

mineral

nutrient

in

each

case,

e.g.

without

magnesium.

to

waste

chlorophyll

needed.

omitting is

Figure

of

4.5.2

mineral

shows

how

deficiencies.

to

use

hydroponics

to

investigate

the

effect

Cotton

Seedling

wool

Black

paper

to

keep

out

light

Figure

2

1

3

4.5.3

Plants

grown

using

4

hydroponics

Normal

culture

No

magnesium

solution

Figure

Plants

they

with

4.5.2

with

deficiency

leaves,

make

leaves.

continually

so

to

nitrogen

cannot

few

How

use

(nitrate)

the

magnesium

older

leaves

to

nitrate

investigate

deficiency

protein.

lower

synthesise

of

hydroponics

much

The

No

ions

They

leaves

chlorophyll

sends

have

a

all

they

very

as

mineral

slowly

A

magnesium

and

of

roots

the

need.

yellow

water

effect

short

yellow

the

mottled

grow

have

turn

the

Distilled

ions

deficiencies

because

and

plants

stems

cannot

plant

with

it

to

has

green

a

the

new

appearance. Figure

4.5.6

Bladderworts

plants

YOU

Pitcher

and

that

animals,

such

insects.

plants,

they

4.5.4

Crop

soils

do

plants

grown

deficient

not

grow

in

in

Figure

4.5.5

A

nitrogen

leaf

trap

They

aquatic

Explain

b

Describe

deficiency

KEY

why

plants

how

the

Plant

roots

nitrate

a

Explain

need

plants

mineral

obtain

appearance

ions

how

they

their

of

plants

nitrate

for

in

ions.

minerals

b

mineral

grown

magnesium

carnivorous

plants

Nitrate

ions

make

are

amino

the

trophic

ions.

obtain

plants

the

mineral

nutrients

3

If

a

levels

in

occupied

wetland

needed

acids;

without:

need.

bladderworts

growth.

ions.

to

mineral

plant

by

carnivorous

ions

make

ions

are

used

by

chlorophyll.

are

develops

such

lacking,

deficiency

as

plants,

yellowing as

ions

healthy

ions.

symptoms, Suggest

such

grow

nitrate

absorb

magnesium

a

b

digest

All

POINTS

to

that

the

and

animals.

in

grow

of

magnesium

2

3

are

QUESTIONS

a

Describe

traps

digest

that

trap

deficient

needed

2

and

throughout

wetlands

including

1

fly

in

1 SUMMARY

small

this

showing

symptoms

well.

as

carnivorous

plants

Caribbean.

Figure

Venus

are

Bladderworts

habitats

trap

flea.

carnivorous

small

green

little

KNOW?

sundews

plants:

are

have

bladders

water

DID

that

of

the

leaves.

ecosystems.

57

Unit

SECTION

1

4

1:

Multiple-choice

Carnivorous

They

use

What

do

digest

Practice

plants

proteins

these

the

trap

from

plants

and

the

exam

questions

digest

insects

produce

in

insects.

5

for growth.

order

catalase

B

proteases

C

hormones

D

hydrochloric

the

plants

elements

by

plants

movement

carry

of

out

gas

Which

gases

at

exchange

summarises

night

night

and

A

calcium,

iron,

carbon

the

oxygen

B

nitrogen,

magnesium,

C

nitrogen,

phosphorus,

D

phosphorus,

The

raw

dioxide

out

out

in

B

out

in

in

out

C

in

out

in

out

D

out

in

out

in

materials

carbon

dioxide,

B

carbon

dioxide

C

chlorophyll

D

chlorophyll,

Most

of

the

A

palisade

B

lower

4

nutrition

C

spongy

D

upper

8

Which

involves

chemical

energy

into

converting

dioxide

simple

complex

feeding

during

complex

carbon

one

on

of

organic

and

organic

light

dead

the

and

compounds

water

light

light

and

chloroplasts

water

in

a

leaf

are

in

the:

mesophyll

of

mesophyll

epidermis

the

following

for

the

of

would

highest

a

rate

tropical

provide

the

of

plant?

Light

Carbon

T emperature/

intensity

dioxide

°C

decaying

following

does

organisms

not

occur

photosynthesis?

of

light

B

conversion

of

glucose

C

reduction

of

by

carbon

splitting

of

water

A

high

low

30

B

low

high

20

C

low

low

30

D

high

high

35

compounds

chlorophyll

to

sucrose

dioxide

to

a

carbohydrate

58

and

compounds

absorption

energy

water

water

inorganic

A

D

and

concentration

converting

Which

are:

epidermis

energy

D

sulfur

photosynthesis

light

and

photosynthesis

into

for

A

conditions

C

potassium,

day

in

converting

potassium

the

A

Autotrophic

potassium

carbon

dioxide

into

magnesium

the

during

During

oxygen

B

largest

with

7

A

in

to

day?

3

required

are:

acid

atmosphere.

At

mineral

insects?

A

Green

The

quantities

6

2

questions

molecules

using

light

SECTION

9

A

1

2:

student

to

Short

used

the

investigate

intensities

pond

on

plant.

temperature

table

shows

answer

the

the

The

apparatus

effect

rate

of

student

throughout

the

questions

of

shown

in

different

the

student’s

i

Describe

would

light

photosynthesis

monitored

a

Figure

the

of

room

investigation.

ii

The

the

these

why

during

iii

collects

State

the

apparatus

tank

with

State

why

down

water

is

(4)

produced

investigation.

(1)

the

the

air

bubble

moves

tubing.

(1)

here

b

i

Calculate

the

rate

photosynthesis Test

to

results.

gas

the

student

results.

Glass

Gas

use

obtain

a

how

of

missing

from

tube

the

Pond

ii

plant

table.

Draw

c

Explain

d

Predict

a

graph

the

the

(1)

of

the

results.

results.

results

(5)

(4)

that

would

0

be

10

obtained

between

Scale/mm

plant

20

is

Explain

when

the

lamp

50 mm

your

the

distance

and

and

the

pond

600 mm.

predictions.

(4)

30

Movement

of

e

i

State

two

sources

of

error

in

40 air

bubble Moveable

this

investigation.

(2)

50 lamp

ii Air

bubble

capillary

in

Suggest

how

this

investigation

60

could

tube

be

improved.

(3)

70

Total

25

marks

80

10

a

Describe

in

a

how

flowering

photosynthesis

occurs

plant.

(5)

Ruler

b

Make

a

fully

showing

structure

Figure

annotated

how

of

a

the

diagram

internal

leaf

is

adapted

photosynthesis.

c Distance

Distance

Rate

Describe

lamp

travelled

by

the

fate

(7)

of

the

products

of

of of

for

1

photosynthesis.

(3)

photosynthesis/

–1

from

pond

plant/mm

air

5

bubble

in

Total

mm/min

100

30

6.0

150

26

5.2

200

14

3.5

300

7

Further

and

on 500

15

marks

minutes/mm

3

practice

examples

the

questions

can

be

found

accompanying

CD.

0.6

59

5

Digestion

5.1

LEARNING

and

T esting

food

The

diet

substances

the

end

should

•

be

this

how

between

starch,

and

that

formed

and

carry

to

our

out

broken

these

eat.

T able

fibre

substances

Details

5.1.1

Nutrient

reducing

are

of

the

Chemical

and

carbohydrates,

are

water.

present

tests

tests

are

for

There

in

samples

given

food

are

in

T able

proteins,

chemical

lipids

of

the

tests

(fats),

to

foodstuffs

show

that

5.1.1.

substances

large

Reagents

Procedure

sugars,

lipids

by

minerals,

distinguish

non-reducing

proteins

are

you

we

to

tests

explain

topic

that

to:

chemical

sugars,

•

of

able

describe

in

substances

OUTCOMES vitamins,

At

breathing

Starch

molecules

Iodine

Add

solution

drops

few

to

sample

condensation

down

a

Positive

Negative

result

result

Blue-black

Yellow-

a

orange

of

food

by

hydrolysis.

STUDY

Reducing

Benedict’s

Heat

in

sugars

solution

boiling

water

(e.g.

bath

with

glucose

solution

and

the

a

of

food

because

the

test

change

from

solution

to

green,

or

–

remains

blue

Boil

acid

with

solution

sugars

sodium

ions.

(e.g.

sucrose)

reducing

to

become

for

copper( )

Hydrochloric

reducing

so

called

reducing

During

sugars

the

copper

copper( )

precipitate

red

Non-

are

copper( II)

electrons

that

red

are

Benedict’s

reaction

ions

The

sugars

they

contains

donate

change

blue

colour

FOCUS

Reducing

the

No

orange

fructose)

agents.

Colour

you

reducing

see

ions.

Colour

No

change

change

cool;

from

solution

hydroxide

neutralise

to

(NaOH),

with

orange

Benedict’s

test

solution

Benedict’s

(HCl),

HCl;

NaOH;

with

solution

in

sugars

sample

blue

green,

or

colour

–

remains

blue

red

as

above

is

oxide. Protein

Biuret

Add

solution

–

a

few

drops

of

solution

biuret

of

solution

sodium

hydroxide

a

(NaOH)

the

and

to

solution

of

Colour

No

change

change

from

solution

to

blue

lilac

or

colour

–

is

blue

purple

sample

copper

sulfate

(CuSO

) 4

Lipids

and

(fats

oils)

Water

and

ethanol

Dissolve

White

No

sample

emulsion

emulsion

Greasy

No

spot

spot

in

ethanol,

pour

into

Filter Figure

5.1.1

Testing

for

paper

Rub

water

the

60

the

food

greasy

reducing

The

into

highest

concentration

on

then

solution

sample sugars.

white

right.

of

sugar

is

the

paper

leave

to

and

dry

which

is

translucent

Precautions:

tubes

into

a

When

water

you

bath.

carry

The

out

the

water

Benedict’s

must

be

at

a

test,

put

the

temperature

test

above

EXAM 80 °C;

it

when

does

not

carrying

have

out

to

these

be

boiling.

tests.

It

is

Always

essential

wear

to

eye

neutralise

the

reaction

Y ou mixture

in

the

non-reducing

sugar

test

because

the

Benedict’s

not

work

if

acid

is

can

call

the

starch

These

do

to

tests

not

tell

modify

biuret

as

of

tests

the

Joining

so

give

and

that

of

and

of

acid

acts

as

solution,

the

people’s

is

are

present,

present.

Benedict’s

colours

starch,

is

water

is

sugar

may

and

more

or

protein

colours

to

a

differ.

acid

catalyst

breaks

of

this

(see

a

bond

bond

5.3).

between

uses

water;

Breakage

of

the

bonds

by 5.1.2

Different

hydrolysis

a

synthesis

of

sucrose

involves

reacting

glucose

and

fructose

chemical

reaction

is

bond

a

molecules,

is

formed

between

condensation

such

as

starch

or

and

a

them

when

dehydration

protein,

involves

water

is

reaction.

forming

formed.

Making

way

–

a

process

known

as

dehydration

many

This

bonds

hydrolysis

and

condensation.

Explain

how

are

involved

in

the

formation

and

breakdown

of

of

Explain

b

Name

the

two

Explain

with

it

A

term

reducing

reducing

how

food

starch

has

contains

food

How

KEY

sample

would

sugar.

sugars

and

differs

from

a

separate

hydrochloric

one

non-reducing

sugar.

hydrolyses

form

right

test

the

solution

sample

to

see

if

sugar .

it

Then

just

been

developed.

non-reducing

is

you

thought

prove

to

sample

acid.

The

molecules

the

reducing

with

acid

of

sucrose

sugars

glucose.

sugar,

How

starch,

would

you

protein

and

contain

both

glucose

and

and

fructose.

confirm

fat?

and

breakdown

of

sucrose

sucrose.

this?

POINTS Removal

forms

1

the

reducing

Synthesis

4

sugar

out

Benedict’s

test

Benedict’s

glucose

that

the

sucrose.

to

novel

carrying

First

any

boil

a

A

on

a

has

3

the

these

with

c

on

highest

QUESTIONS

processes

2

the

FOCUS

non-reducing

twice.

molecule

solution:

with

in

testing

Define

0%,

synthesis

involves

1

is

concentration

The

SUMMARY

biuret

of

tested

larger

STUDY

this

solution

together . left

A

concentrations

protein

with

The

it

they

Figure

using

‘iodine

call

possible

solution

comparing

judgment

It

become

reducing

by

no t

molecules

breakage

a

The

obtained

hydrochloric

The

substances

Do

‘iodine ’.

tests

substance

colours.

are

breaking

with

food

each

iodine

results

fructose.

hydrochloric

the

of

ranges

standards

and

chemical

concentration

sucrose

glucose

much

However,

colour

Boiling

these

whether

how

the

increases.

set

show

us

solution

intense

of

reage nt

test

present.

so lutio n’.

Limitations

the

test

fo r does

TIP

protection

Benedict’s

solution

solution

used

is

proteins;

the

to

is

used

test

emulsion

for

to

identify

starch;

and

greasy

reducing

biuret

spot

sugars;

solution

tests

tests

identify

of

water

Addition

bond

breaks

of

water

bond

iodine

for

lipids.

+ 2

Sucrose

and

starch

are

formed

by

condensation

reactions

Glucose

between

smaller

hydrolysis

molecules.

reactions.

These

bonds

are

broken

Fructose

by

Figure

5.1.3

The

synthesis

breakdown

and

of

sucrose

61

5.2

T eeth

The LEARNING

digestive

the

end

should

•

be

identify

of

this

able

the

human

topic

you

the

to:

parts

of

alimentary

the

canal

ingest

digested.

on

This

pancreas

part

to

•

the

of

its

structure

the

of

alimentary

canal

the

structure

(Figure

all

in

chewing

the

mechanical

role

of

the

of

that

is

the

mouth,

fat

do

consists

and

the

organs,

of

then

the

egest

tissues

and

anything

Chemical

of

are

a

as

in

not

digestion

starch,

broken

alimentary

canal,

the

is

liver

not

and

breakdown

churning

the

small

change

of

of

food

intestine.

the

food

in

into

the

These

chemical

stomach

are

nature

smaller

pieces

and

physical

of

food.

teeth

into

down

is

the

breakdown

small,

by

soluble

hydrolysis,

of

large,

molecules.

catalysed

by

insoluble

Large

molecules,

molecules

enzymes

within

the

canal.

in

digestion.

Soft Mouth

SUMMARY

palate

cavity

QUESTIONS (buccal

cavity)

Throat

1

cells

that

5.2.1).

by

alimentary

describe

system

digestion

such

tooth

•

of

food

each

functions

describe

consists

digest

Mechanical

processes relate

and

emulsification

diagrams

•

system

guts

OUTCOMES that

At

and

Distinguish

between

(phar ynx)

mechanical Mouth Epiglottis

and

chemical

digestion. Tongue

2

Describe

the

role

of

teeth

in Salivar y

feeding

and

gland

digestion.

Gullet

3

Describe

what

happens

to (oesophagus) Diaphragm

food

small

in

the

stomach

and

the

Ring

intestine.

of

muscle

(pyloric

Describe

the

roles

liver

the

pancreas

sphincter)

the

in

the

Stomach

Liver

system. Gall

bladder Duodenum

Bile

duct

Enamel Ileum Pancreas

Pulp

llamS

and

digestive

of

enitsetni

4

cavity

Caecum

Appendix

Gum Abdominal

cavity

Root Rectum

Cement

Anus

Nerves

Ring

of

around

blood

Figure

5.2.2

A

vertical

molar

62

section

tooth

of

muscle

and

vessels

a

Figure

5.2.1

The

human

alimentary

canal

anus

enitsetni

Colon

Dentine

egraL

Crown

T able

Part

5.2.1

of

Functions

the

digestive

of

the

digestive

system

Functions

system

Mouth

•

mastication

•

secretion

•

food

Oesophagus

•

transfers

Stomach

•

wall

•

muscular

of

Gall

bladder

Pancreas

Small

intestine

Anal

intestine

canal

mechanical

into

food

wall

by

digestion

salivary

boluses

by

stomach

that

peristalsis

secretes

mixes

glands;

can

from

gastric

food

with

of

food

salivary

be

the

teeth

begins

and

the

tongue

digestion

of

starch

swallowed

mouth

juice

using

amylase

to

stomach

containing

gastric

juice

and

hydrochloric

breaks

up

acid

large

and

pieces

pepsin

of

food

into

a

mixture

•

pepsin

begins

•

no

•

secretes

bile

•

secretes

sodium

•

stores

•

secretes

pancreatic

•

secretes

sodium

•

secretes

the

digestion

bile

digestion

Large

–

saliva

formed

creamy

Liver

of

the

of

starch

that

and

as

contains

releases

•

absorbs

products

•

absorbs

water,

•

absorbs

the

•

stores

•

faeces

of

ions

in

the

out

of

salts

into

that

the

to

not

small

carbonate

function

emulsify

to

contains

fats

neutralise

intestine

amylase,

to

maltase,

acid

(see

trypsin

and

environment

5.3)

stomach

through

neutralise

lactase

in

acid

the

and

stomach

bile

duct

lipase

acid

peptidase

that

complete

the

protein

digestion

and

remaining

does

carbonate

sucrase,

and

protein

bile

hydrogen

starch

faeces

it

juice

of

amylase

hydrogen

enzymes

of

pass

digestion

into

vitamins

water

the

into

and

bloodstream

the

bloodstream

ions

rectum

the

body

KEY

POINTS

T eeth 1

Chewing

It

also

juice.

We

food

decreases

increases

Chemical

have

four

the

its

surface

digestion

types

particle

of

is

area

size

that

much

is

so

we

are

exposed

faster

if

the

able

to

to

saliva

particles

swallow

and

are

Mechanical

the

it.

into

gastric

2

teeth:

Chemical

the •

Incisors

are

•

Canines

chisel-shaped

for

biting

and

smaller

mastication

smaller.

pointed

for

piercing

and

Premolars

•

Molars

have

are

like

uneven

‘cusps’

premolars

and

for

are

and

chewing

chewing.

up

the

small

the

section

through

a

molar

tooth

(see

Figure

5.2.2).

In

by

Enamel

forms

the

hard,

outer

layer

is

the

part

above

the

the

of

the

crown

of

the

Inside

the

enamel

is

the

to

stomach,

up

food

and

gastric

is

mixed

juice

and

tooth, acid.

This

starts

gum. the

•

to

molecules

molecules.

hydrochloric which

involves

chemical

hydrolysis

large

churned

with •

digestion

teeth.

food. 3

Study

e.g.

the

tearing.

grinding

for

pieces,

of

is

food

cutting.

change

•

of

using

breaking

bonds

are

digestion

breakdown

softer

dentine,

which

is

like

bone

digestion

of

protein.

in

4

structure.

Bile

emulsifies

fats

in

the

duodenum. •

A

layer

the

•

The

of

jaw.

The

pulp

blood

cement

root

cavity

vessels.

is

is

fixes

the

the

part

a

space

root

that

in

of

is

the

the

tooth

below

tooth

the

into

a

bony

socket

gum.

containing

in

5

nerves

and

Enzymes

produced

pancreas

intestine

chemical

proteins

and

the

the

small

complete

digestion

and

by

the

of

starch,

fat.

63

5.3

Enzymes

The LEARNING

as

At

the

end

should

be

food

that

of

this

able

topic

you

starch,

define

the

wall

into

to:

of

small,

the

term

state

that

enzymes

biological

catalysts

the

the

intestine.

soluble

(see

bodies

catalyst

itself

describe

composed

fats.

They

of

This

means

molecules.

5.1).

The

are

large,

The

natural

too

insoluble

large

that

they

breakage

rate

of

to

be

molecules

need

of

the

hydrolysis

absorbed

such

to

be

broken

bonds

at

the

through

down

involves

temperature

is

very

slow.

The

rate

needs

to

be

speeded

up

by

a

of

catalyst.

are A

•

is

and

catalyst our

•

eat

proteins

hydrolysis

•

we

OUTCOMES

properties

is

being

a

substance

changed.

that

increases

Biological

the

catalysts

rate

are

of

a

reaction

enzymes

without

(Figure

5.3.1),

of which

are

proteins.

All

enzymes

are

made

inside

cells,

where

many

of

enzymes them

•

describe

in

the

chemical

role

of

enzymes

pass

work,

out

from

of

Enzymes

the

have

•

They

are

•

Each

enzyme

•

Only

A

of

the

enzyme

catalase

stomach

our

and

food

small

the

enzymes

intestine.

small

over

period

is

affected

by

pH.

different

it

protein

shapes.

specific

for

Each

are

needed

to

catalyse

time.

activity

of

and

of

Their

made

again

molecules

•

are

used

a

enzyme

temperature.

are

many

different

substrate

part

the

again.

molecules.

enzyme

catalysing

in

model

of

the

of

shape

‘key’)

one

are

a

fit

in

activity

(the

influenced

one

These

molecule

reaction.

is

can

has

This

an

are

you

fits

be

a

folded

shape

explains

each

into

enzyme.

not

as

shape

as

for

that

known

a

‘lock’)

the

by

and

have

by

enzyme

shape

catalysed

to

must

enzyme

–

with

reaction

enzyme

(the

the

enzymes

molecule

wrong

Enzymes

‘the

into

that

why

that

conditions

the

there

‘lock

fits

see

of

in

and

reaction.

key’.

into

Figure

their

will

substrates

the

exactly

in

Only

enzyme

Other

involved

the

can

reaction.

The

the

‘key

5.3.2.

surroundings.

If

enzy me the

Enzy mes

conditions

organi sms.

become

too

hot,

too

acid

or

too

alkaline

their

shape

are changes

and

they

stop

acting

as

catalysts.

At

high

temperatures

and

T hey at

co rrec t

be

of

reaction.

by

hole’

pro tei n

numbers

one

affected

the

TIP

are

catalyses

is

substrate

T he

properties:

proteins.

reactions

can

following

activity

This

say

all

enzymes

Their

have

kille d’.

mouth,

digest

•

take

is

the

T o

computer-generated

image

no t

respiration.

They

makes

Never

into

in

•

many

EXAM

cells

Properties

Enzymes

5.3.1

example

digestion.

many

Figure

for

extreme

pH,

the

bonds

holding

the

enzyme

changes

the

shape

molecule

together

mo lec ules. start

wo rd

to

use

is

to

break

substrate

no

down.

longer

This

fits.

We

say

that

of

the

enzyme,

denaturation

has

so

the

occurred

and

dena tured the

enzyme

Enzymes

The

down

glucose

digestive

64

in

enzymes

break

to

can

in

no

catalyse

the

reaction.

digestion

our

large

and

longer

digestive

molecules

proteins

enzymes

is

to

system

to

catalyse

smaller

amino

summarised

acids.

in

hydrolysis

molecules,

for

Information

T able

5.3.1.

reactions

example

about

to

starch

these

STUDY

Y our

learning

could

the

Enzyme

Substrate

Substrate

into

fits

Enzyme

Products

enzyme

FOCUS

digestive

Label

all

the

5.3.2

Lock

and

key

–

a

model

of

enzyme

each

action

T ype

Digestive

of

enzymes

Name

enzyme

of

made

Site

in

the

of

human

digestive

production

Carbohydrase

Protease

Lipase

and

of

action

Reaction

Salivary

glands

Mouth

starch

Small

intestine

→

Sucrase

Wall

of

small

intestine

Small

intestine

sucrose

Lactase

Wall

of

small

intestine

Small

intestine

lactose

Maltase

Wall

of

small

intestine

Small

intestine

maltose

Pepsin

Stomach

Trypsin

Pancreas

Peptidases

Wall

Lipase

Pancreas

of

wall

Catalysts

speed-up

end;

enzymes

of

of

sites

of

in

the

action.

by

enzyme

small

intestine

protein

Small

intestine

polypeptide

Small

intestine

peptides

Small

intestine

lipids

→

+

fructose

galactose

peptides

→

→

(fats)

+

glucose

shorter

amino

→

peptides

acids

fatty

acids

+

glycerol

FOCUS

a

reaction

are

and

biological

remain

catalysts

unchanged

that

are

at

made

is

insoluble

makes

of

fat

it

hard

forms

are

specific

to

certain

in

In

chemical

insoluble

digestion,

molecules

smaller,

catalyse

soluble

the

hydrolysis

of

large

molecules.

fat

reach

break

up

smaller

QUESTIONS

fat

the

digestion

Make

a

and

table

nutrients:

have

following

the

to

Some

the

food

make

summarise

starch,

protein,

following

in

a

catalyst,

enzyme,

chemical

of

the

enzyme(s),

contains

starch,

to

of

these

Your

nutrient,

product(s)

as

they

pass

roles

of

the

liver

what

through

and

as

globules

the

globules

ones.

the

the

This

of

bile

fat

of

salts

into

emulsification

surface

so

area

molecules

access

bonds

and

to

the

of

of

fat

between

the

lipase

to

fatty

glycerol.

should

enzyme(s),

digestion,

site

site(s)

of

and

fat.

Use

happens

to

T able

these

5.3.1

three

the

alimentary

canal.

5.3.3

pancreas

in

your

flow

Large

globules

of

fat

are

Include emulsified

the

these

food

table

Figure

nutrients

the

system.

protein

show

of

sucrose.

food

digestive

chart

digestion

and

headings:

human

flow

acids

fat

to

canal

duodenum,

easier

break

denaturation

production

action

terms:

the

globules

the

globules

have

Define

This

as

surface

alimentary

When

increases

SUMMARY

spherical

little

the

water .

digest

reactions.

enzymes

to

as

in

to

into

exposing

Enzymes

to

the

enzymes

sites

glucose

possible.

3

the

glucose

→

water

of

of

their

→

Stomach

protein.

2

Include

POINTS

the

1

and

functions

maltose

→

Fat

3

the

catalysed

STUDY

2

of

5.2).

system

Site

Pancreas

1

topic

enzyme

Amylase

KEY

this

diagram

(see

regions

region.

table

5.3.1

for

large

system

with

production

T able

a

released

annotate

Figure

notes

include

to

smaller

globules

so

that

lipase

chart. can

catalyse

glycerol

the

more

formation

of

fatty

acids

and

easily.

65

5.4

Factors

that

affect

enzymes

Effect LEARNING

of

Amylase At

the

end

of

this

topic

be

•

that

able

is

that

the

activity

of

enzymes

catalyst

from

for

5.1

the

that

breakdown

iodine

of

solution

starch

is

to

used

maltose.

to

detect

You

the

to:

pH

temperature

the

remember

presence

state

on

you will

should

temperature

OUTCOMES

is

and

are

influence

this

factors

the

less

activity

by

iodine

of

of

and

starch.

less

taking

As

starch

the

samples

solution

as

starch

present

from

shown

in

in

is

broken

the

the

reaction

Figure

down

reaction

by

amylase,

mixture.

mixture

You

and

there

can

testing

follow

with

5.4.1.

enzymes T able

•

explain

how

to

investigate

5.4.1

reaction

influence

pH

on

of

the

temperature

activity

of

shows

mixtures

one

results

kept

at

from

an

different

investigation

in

which

seven

temperatures.

and

5.4.1

Effect

T emperature

at

were

enzymes. T able

Remove

some

the

(°C)

of

temperature

Time

be

samples

on

taken

amylase

for

digested,

t

starch

to

Rate

(minutes)

as

of

reaction

10/t

minute

0

–

0

10

9

1.1

20

7

1.4

30

6

1.7

40

4

2.5

50

8

1.3

60

–

0

intervals

Test

samples

with

drops

iodine

Spotting

solution

Figure

and

amylase

5.4.1

of

solution

tile

solution

Samples

STUDY

taken

from

the

Divide reaction

tube

of

mixture

are

iodine

minute

added

in

to

solution

until

there

FOCUS

the

digested

every

is

1,

in

the

100

or

10 000

is

(reciprocal).

working

very

fast.

This

by

the

Then

gives

time

we

large

taken

for

have

numbers

starch

peaks

on

a

when

to

graph

the

be

enzyme

when

the

no

enzyme change

10,

test

drops

is

most

active

rather

than

when

it

is

least

active

if

we

colour.

plotted

time

taken.

3.0

The

graph

in

Figure

5.4.2

shows

that

the

rate

of

reaction

is

2.5 t /01

o

slow

sa

2.0

the

at

low

temperatures,

temperature

etar

40 °C

(optimum

for

increases

to

example

40 °C

temperature).

The

at

10

C.

and

reaches

rate

of

It

a

increases

as

maximum

reaction

at

decreases

at

1.5 o

noitcaeR

temperatures

greater

than

40

C

and

is

zero

at

60 °C.

1.0

The

0.5

As

of

optimum

the

temperature

temperature

substrate

and

increases

enzyme

is

the

best

towards

move

faster

temperature

the

and

optimum,

have

more

for

the

enzyme.

molecules

collisions

so

0.0 0

10

20

30

40

50

60

70

Temperature/°C

Figure

5.4.2

Effect

the

66

of

temperature

activity

of

more

reactions

changes

on

amylase

have

to

and

test

optimum

at

occur.

60 °C

At

all

higher

the

temperatures

temperature.

temperatures,

enzyme

between

the

molecules

30 °C

and

enzyme

are

50 °C

structure

denatured.

to

find

the

We

exact

Effect

of

pH

on

the

activity

of

catalase STUDY

Catalase

is

an

enzyme

found

inside

many

cells.

Its

function

is Here

to

catalyse

the

breakdown

of

hydrogen

peroxide.

This

is

a

that

is

produced

by

cells

which

can

do

are

damage

if

optimum

accumulate.

It

catalyses

this

and

plant

peroxide

→

oxygen

+

is

found

bacteria

and

1

cork

in

many

plant

and

animal

tissues;

it

is

also

found

in

a

cores

into

2

Put

three

3

Put

the

produced

borer

to

smaller

pieces

remove

sections

into

a

several

that

cores

are

solution

from

each

with

a

a

about

pH

of

potato.

2 mm

in

Cut

volume

of

hydrogen

peroxide

by

enzymes

bacteria

and

Put

one

potato

disc

into

the

test

tube

at

5

As

soon

find

The

Repeat

7

pH

When

all

the

are

the

how

forms

disc

with

less

two

the

starts

it

test

to

takes

between

which

the

disc

long

of

inside

dense

more

the

so

discs

to

the

disc

catalase

to

and

7.0.

into

pH

some

7.0.

surface,

reach

It

test

will

and

start

the

hydrogen

potato

it

so

5.4.2

Effect

the

to

whole

find

the

investigating

other

valid

and

due

procedure

optimum

the

factors

SUMMARY

effect

should

only

timing

and

surface.

peroxide

produces

on

the

activity

Time

taken

for

discs

to

reach

the

underneath

the

disc,

surface

(seconds)

First

Second

Third

Mean

disc

disc

disc

(average)

4

36.03

37.13

38.59

37.25

5

15.77

12.93

14.35

14.35

6

12.06

10.05

11.03

11.05

7

9.13

10.13

9.63

9.63

8

9.67

10.29

9.98

9.98

9

10.81

12.69

11.87

11.79

floats.

that

there

are

three

readings

for

to

be

the

with

pH

of

discs

for

factor

a

range

of

other

values

catalase.

one

kept

at

factor

on

constant.

that

has

the

This

been

activity

ensures

of

enzymes,

the

results

STUDY

Sketch

a

graph

human

to

so

on

the

enzyme,

b

Describe,

a

Use

in

show

rate

such

words,

the

of

as

effect

a

is

catalysed

by

the

results

effect

of

in

pH

T able

on

the

to

by

your

Describe

c

Explain

the

pattern

activity

why

it

is

a

why

there

shown

good

by

idea

draw

of

about

this

Summary

2c.

a

line

graph

to

POINTS

show

catalase.

your

to

Think

answer

results

graph.

1

b

readings

three

amylase.

shown

5.4.2

repeat

are

disc?

then

question

a

two

there

each

KEY the

take

that

and

increasing

reaction

salivary

what

of

FOCUS

changed.

QUESTIONS

temperature

2

pH

catalase

sink

for

a

of

tubes.

Why

1

90 °C.

tube.

rise

the

in

7.0.

Repeat

of

bottom

reaction

making

pH

as

out

oxygen

6

the

use

thickness.

pH

towards

for

forensics

of

4

human

(body

the

T able

same

37 °C

temperature);

fungi.

industry Use

20 °C;

water enzymes

Catalase

enzymes

reaction: approximately

hydrogen

examples

temperatures:

allowed fungal

to

some

toxic of

substance

FOCUS

graph.

have

three

The

is

results

for

activity

of

influenced

enzymes

by

pH

and

temperature.

each

pH. 2

d

Explain

from

3

a

these

Sketch

a

rate

an

pH

of

is

above

b

Suggest

below

the

optimum

pH

to

show

the

effect

there

is

no

of

reaction

activity

increasing

pH

where

optimum

below

pH

the

4.0

and

on

the

none

10.0.

why

pH

about

the

4.0

An

at

3

effect

on

enzyme

above

in

this

pH

example

10.0.

shows

no

activity

is

most

optimum

When

all

and

enzyme

its

optimum

enzyme-catalysed

and

pH

uncertainty

results.

graph

6.5

is

pH

active

and

temperature.

investigating

of

the

one

factor

activity

other

of

factors

temperature)

the

(e.g.

an

pH)

enzyme,

(e.g.

should

be

kept

constant.

67

5.5

Absorption

and

assimilation

Absorption LEARNING

At

the

end

should

be

OUTCOMES

of

this

able

topic

Absorption

is

blood

lymph.

or

define

and

the

terms

by

absorption

pass

diffusion

movement

Simple

of

digested

sugars,

food

amino

molecules

acids,

fatty

into

acids

the

and

through

or

by

the

active

epithelial

cells

of

the

small

intestine

either

transport.

assimilation The

•

the

to: glycerol

•

the

you

describe

how

the

for

intestine

is

small

intestine

is

very

long

(about

6 m

in

an

adult)

and

is

adapted

small

adapted

efficient

absorption

of

food

as

it

has:

for 2

•

a

very

large

surface

•

a

thin

lining

area

of

about

9 m

absorption

•

describe

the

role

of

the

molecules in

of

epithelial

cells

(only

one

cell

thick)

so

that

food

liver

can

easily

move

into

the

blood

and

lymph

assimilation.

•

epithelial

•

cell

The

large

The

is

finger-like

quickly

acids

villi

are

to

and

have

blood

5.5.1

These

small

are

villi

from

intestine

leaf-like

and

–

are

the

the

of

glycerol

leaf-like

en ters

by

are

vessels

the

a re

the

th e

ly mph

h eart.

As

a

fits

transport

into

inner

the

(the

with

full

a nd

lacteals

vein

in

in to

a nd

result,

f at

5. 5. 3).

em pty

does

not

vessels.

in to

en ter

qu ick ly.

villus

Network

Epithelium

blood

of

capillaries

Mucus-

secreting

cell

Lacteal

muscle

Venule

layer

Arteriole

Lymphatic

68

Longitudinal

section

through

a

villus

T he

lac teals

ly m pha tic

they

Fa tty

lym ph.

the

capillaries.

5.5.2

of

(lymph

are

Figure

space

tr a nspor ted

the

c ontr a c ts

m ove

veins,

(Figur e

slo wly

this

are

of

Thin

3.4).

millions

singular

the

they

(see

small

lining

villi

m olec ules

more

to

like

3.1)

active

called

po r ta l

When

A

blood

f ood

hepatic

in

5.5.2).

capillaries

t hem.

for

folded

Figure

th in -walled,

th e

a

projections

and

3.1.2

intestine

has

transported

in side

near

too

it

Figure

proteins

small

Absorbed

causin g

vessels

the

5.5.1

(see

carrier

because

villi.

liver

muscle

bloodstream Figure

food

in

squeezed

These

or

(Figure

digested

capillaries)

many

area

abdomen

villus)

microvilli

with

surface

the

tiny,

villi

with

membranes

within

of

cells

vessel

the

When

the

food

gets

to

the

colon

there

is

not

much

left

that

is

useful. LINK

What

been

The

is

left

now

absorbed

solid

food,

is

in

in

waste

the

fibre,

the

or

form

dead

small

faeces

of

cells

and

intestine;

is

stored

faeces,

the

in

passes

bacteria.

rest

the

out

is

Most

the

the

absorbed

rectum.

of

of

The

body

by

water

the

has

colon.

Undigested

confuse

See

the

it

takes

between

24

and

48

hours

for

food

the

length

of

the

digestive

is

egested.

with

Do

excretion.

to

pass

glossary

on

the

CD

anus. remind

yourself

about

the

along difference

the

this

undigested

through

to Normally

food

not

between

the

two.

system.

Assimilation

The

food

molecules

that

and

up

have

been

absorbed

are

transported

around

Hepatic

vein

Stomach

the

body

molecules

functions

taken

by

as

the

cells.

part

of

by

cells.

The

liver

Assimilation

carries

out

a

is

the

use

number

of

of

these

important

assimilation: Liver

•

It

takes

up

glucose

glycogen.

This

molecules

helps

to

from

regulate

the

the

blood

and

stores

concentration

of

them

as

glucose

in

Hepatic

portal

the

blood.

vein

•

It

uses

blood

amino

acids

to

make

proteins,

such

as

those

involved

in

clotting.

•

It

breaks

down

•

It

converts

surplus

amino

Large

acids.

intestine

the

body,

fatty

e.g.

acids

under

and

the

glycerol

into

fat

which

is

stored

around

Small

skin.

intestine

•

It

produces

cholesterol

from

fats.

Anus

KEY

Figure

POINTS

5.5.3

Rectum

The

hepatic

carries

1

Absorption

is

the

movement

of

digested

food

stomach

molecules

the

through

2

the

Assimilation

wall

is

of

the

the

use

intestine

of

food

into

the

molecules

blood

by

the

and

cells

portal

blood

vein

from

and

the

intestines

to

liver.

lymph.

of

the

body. DID

3

The

small

intestine

is

adapted

for

absorption

by

being

The long,

having

a

folded

inner

lining

with

millions

of

tiny

YOU

small

villi.

increase

the

surface

area

of

each

epithelial

The

liver

stores

glucose

as

glycogen,

makes

proteins,

absorbs

about

of

water

every

day.

cell. As

4

intestine

3

5–10 dm Microvilli

KNOW?

very

food

more

breaks

passes

water

is

along

the

absorbed

colon,

into

3

down

surplus

glycerol

back

SUMMARY

1

Make

a

into

acids

fat

for

and

converts

fatty

acids

and

storage.

the

blood:

per

day.

by

labelled

writing

diagram

notes

of

about

a

villus.

the

Annotate

functions

of

have

parts

that liver

is

Distinguish

between

absorption

and

in

assimilation.

the

and 3

Explain

also

involved

in

the

labelled. regulation

2

0.3–0.5 dm

LINK

your

the

The you

about

QUESTIONS

large

diagram

amino

how

the

liver

is

involved

in

assimilating

the

products

of

body,

amino

many

such

acids.

substances

as

glucose

There

is

more

of about

its

waste

substances

role

in

producing

digestion.

4

Suggest

the

danger

in

having

too

much

fat

in

the

blood.

excreted

from

the

that

are

body

in

7.1.

69

5.6

Balanced

A LEARNING

nutrient

the

end

should

be

of

this

able

topic

energy

define

the

quantities:

to:

term

nutrient

to

the

human

list

the

their

•

main

roles

explain

in

in

the

nutrients

the

term

need

food

These

is

that

are

carbohydrates,

but

also

the

provided

provides

the

fats

by

the

benefit

organic

and

compounds

major

to

the

compounds

proteins.

like

nutrients

body.

amino

Not

we

only

acids,

or

eat

do

sugars

in

they

and

large

provide

fatty

that

we

need

to

make

our

cells.

Vitamins

and

minerals

are

the

diet minor

•

we

as acids

applied

substance

that

macronutrients.

you

energy

•

a

OUTCOMES The

At

is

diet

and

are

body

nutrients

needed

minerals

in

that

or

micronutrients

tiny

we

quantities.

need

are

that

do

Vitamins

inorganic

not

are

and

provide

organic

are

energy

and

compounds;

often

absorbed

as

the

ions.

balanced A

balanced

diet

provides

all

the

energy

and

nutrients

that

a

person

diet requires

energy

•

essential

•

such

and

to

keep

us

as

the

that

are

as

the

brain,

alive.

basal

need

can

active.

need

essential

the

is

The

more

eight

to

anything

–

two

proteins

ten

diet

provides:

provide

types

of

this

amino

energy

acid

that

the

else

fatty

acids

that

the

body

cannot

more

that

required

Our

e.g.

vitamins

•

minerals,

e.g.

calcium

•

enough

•

fibre.

A

and

C

and

iron

water

to

replace

water

that

is

lost

each

day

so

when

active

you

for

else

or

energy

energy

anything

vitamins,

we

How

much

energy?

you energy

that

we

need

in

our

diet

depends

on

age,

gender,

need and

activity

(how

much

exercise).

People

who

play

sport,

your do

basal

acids

and

balanced

known

rate.

contract

from

occupation

above

–

from

•

The

are,

acids

make

fatty

lipids

A

energy

metabolism

also

they

liver,

This

metabolic

muscles

amino

needs.

FOCUS

kidneys

basal

immediate

carbohydrates,

cannot

make

Organs,

–

their

•

body

STUDY

for

a

lot

of

fitness

training

or

have

an

occupation

that

involves

taking

metabolism. much

exercise

American

8000

and

to

9000 kJ

their

energy

they

large

intake

have

intake

require

football

by

a

each

size.

by

energy

need

day

to

build.

75–80%

to

of

2000 kJ

that

that

the

players

Female

of

than

increase

because

Basketball

1000

lighter

about

more

players

as

their

required

need

of

to

training

should

by

in

T able

energy

intensity

only

athletes

shown

their

their

less

by

training

increase

is

5.6.1.

intake

their

intense

increase

their

and

energy

men.

Vegetarianism

Some

they

are

people

eat

animal

origin.

people

who

A

properly

who 5.6.1

Fresh

fruit

should

be

everyone’s

70

and

a

do

get

foods

eat

are

many

vegetarian

balanced

not

they

are

products,

Vegans

We

are

plant

that

animal

vegetarians.

includes

Figure

decide

some

that

people

of

or

our

provide

and/or

do

have

these

is

are

not

to

eat

and

meat

milk.

eat

from

make

any

although

These

foods

eating

sure

people

of

animals,

that

their

so

diet

nutrients.

a

at

to

eggs

nutrients

diet

fish

going

as

who

vegan

vegetarian

meat

not

such

healthy

risk

of

diet.

However,

vitamin

B 12

people

deficiency

vegetables

major

diet.

part

of

as

this

red

is

only

blood

found

cells.

in

foods

of

animal

origin.

We

need

it

to

make

T able

5.6.1

Different

energy

needs

for

people

who

take

little

exercise

DID

Age

Recommended

energy

YOU

Other

per

day

factors

energy

Females

body

people

mass

influence months

10–12

7–10

(fed

on

formula

milk)

2280

months

years

3850

3610

8240

7280

years

11 510

8830

19–49

years

10 600

8100

months

of

pregnancy

10 600

in

climates

cold

energy

since

generate

years

1

8000

9930

A

and

minerals

quantities

make

for

each

from

many

are

micronutrients,

day.

Vitamins

anything

are

simpler.

because

complex

Minerals

you

need

molecules

different

Some

functions,

micronutrients,

A

substance

Macronutrients

as

you

can

are

see

elements

in

T able

that

large

in

benefit

are

quantities

very

we

small

to

required

their

functions

in

the

body

and

Function(s)

Helps

rods

light

in

in

of

the

the

low

body

eye

to

intensity

Good

8.5)

good

respiration

in

Carbohydrates,

are

the

proteins

and

Liver ,

chili

milk,

sweet

macronutrients

energy

and

dietary

sources

for

vitamins

are

the

are

required

building

and

minerals

micronutrients

for

other

and

roles.

powder ,

potatoes,

aerobic

needed

we

Vegetarians

do

not

eat

meat

carrots or

Helps

are

day;

5.6.2.

4

(see

each

quantities.

compounds

see

B

a

body.

cells;

Micronutrient

is

micronutrients

very

that

sources

Vitamins

to

maintain

provides

providing 5.6.2

to

temperature.

that

lipids

T able

need

heat

more

minerals

3 need

require

they

nutrient

in

cannot

a

live

7990

2 vitamins

and

energy

who

POINTS

the

small

Those

body

body

food

Vitamins

Height,

also

10 900

50–59

of

much

needs.

KEY

Roles

how

build

8900

Breastfeeding

60–64

require.

and

person

their

3

the

2160

15–18

Last

influence

(kJ)

Males

0–3

KNOW?

intake

fish,

animal

Cereals

although

products,

some

such

eat

as

1

in

milk

mitochondria

not C

Helps

tissue

resistance

repair

to

and

Oranges,

disease

and

and

eat

eggs.

any

Vegans

animal

do

products.

lemons

other

citrus

fruits SUMMARY

D

Helps

absorption

calcium

in

the

strengthening

and

Minerals

Iron

teeth

Forms

(see

part

cells

oxygen

gut

of

Fish

and

bones

5.2

and

in

7.4)

to

the

in

red

(also

skin

made

1

2

eggs

Gives

the

and

Explain

why

transports

of

the

teeth;

needed

in

nervous

to

bones

and

Milk,

fish,

for

Name

synapses

diet

quantities

macronutrients.

four

blood

and

vitamins

that

and

humans

two

require

vegetables the

diet.

Suggest

some

occupations

clotting

that 5.2

human

large

system;

4

(see

the

green

in

in

micronutrient,

6.4)

strength

involved

nutrient,

mineral

contain

minerals

the

terms

vitamin

must

3

Calcium

Define

macronutrient,

exposed

meat,

cocoa,

QUESTIONS

milk,

sunlight)

Liver,

that

(see

oil,

butter

of

haemoglobin

blood

of

require

a

higher

intake

7.4)

of

energy

the

than

those

given

in

table.

71

5.7

Malnutrition

Malnutrition LEARNING

OUTCOMES

People At

the

end

of

this

topic

who

do

not

malnutrition. should

be

able

explain

the

There

a

are

balanced

forms

of

diet

may

suffer

malnutrition

from

caused

a

by

form

not

of

enough

to: of

•

have

you

term

the

macronutrients,

or

too

much,

which

can

lead

to

obesity

deficiency Protein

energy

malnutrition

(PEM)

occurs

in

children,

who

do

not

disease

•

describe

energy

the

effects

of

receive

enough

caused

by

state

and

not

and

receiving

protein

enough

in

their

diet.

Marasmus

energy-providing

foods,

is

so

mainly

protein

is

deficiency used

•

energy

protein

the

causes,

treatment

blindness,

symptoms

of

scurvy,

loss.

in

night

rickets

and

to

provide

energy.

Kwashiorkor

the

blood

is

also

swelling

of

helps

absorb

to

Growth

body

the

is

retarded

result

tissues

water

of

and

from

a

a

and

protein

swollen

the

there

is

severe

deficiency

liver.

Protein

and

in

weight

results

the

tissues.

anaemia

Deficiency •

describe

more

to

the

food

effects

than

maintain

is

good

of

necessary

health.

Deficiency

diet.

front

YOU

Eating

and

but

A

too

eating

be

a

much

large

vitamin

A

of

rarely

too

causing

the

eye

are

A

caused

in

night

the

by

diet

blindness.

becomes

cloudy

the

the

If

and

lack

rods

the

light

of

in

micronutrients

the

eye

deficiency

cannot

do

is

pass

not

in

the

work

serious

then

through

the

easily.

vitamins

does

much

lethal.

fishermen

of

of

vitamin

KNOW?

minerals

may

diseases

Without

properly,

DID

diseases

eating

once

A

vitamin

group

ate

halibut

harm,

the

and

of

liver

died

of

poisoning.

Figure

5.7.1

One

of

causes

the

of

children

major

Figure

blindness

is

vitamin

5.7.2

X-ray

in

child

of

the

with

legs

of

a

rickets

A

deficiency.

Without

Vitamin

outwards

has

wear

this

Vitamin

C

5.7.3

This

person

has

iron,

quantity

of

and

bleed

red

oxygen

A

for

C

blood

the

and

teeth

blood

People

out

often

bow

that

sunshine,

body

are

can

most

lead

a

person

or

at

to

who

risk

of

weak

clotting.

fall

formation

out

the

are

of

Wounds

(Figure

contain

in

who

the

calcium

scurvy.

cells

bones

indicating

in

their

of

proper

causes

Leg

body,

go

covers

transported

anaemia.

the

not

defi ciency

slow

vitamin

the

of

do

soft.

less

blood

collagen

are

not

the

skin.

5.7.3).

haemoglobin

decreases.

anaemic

in

repaired

have

less

This

so

is

energy

the

iron-

and

scurvy.

feel

72

of

Without

who

completely

required

gums

deficiency

Figure

is

become

pressure

disease.

teeth,

deficiency

properly,

the

that

deficiency

and

bones

Children

clothing

bones

A

under

rickets.

D

tired

and

lethargic

because

they

have

less

oxygen

available

for

aerobic

respiration.

They

are

likely

to

grow

and

develop

slowly.

Girls DID

and

women

lose

blood

are

in

more

their

at

risk

monthly

of

iron-deficiency

anaemia

because

YOU

The

periods.

advice

from Deficiency

diseases

are

treated

by

making

sure

people

have

the

diet

and

by

giving

dietary

supplements,

such

as

pills

and

here

diet.

comes

DASH

for

Dietary

Approaches

with to

vitamins

given

DASH

a stands

balanced

KNOW?

they

Stop

Hypertension.

It

has

minerals. proved

successful

lowering

blood

not

only

pressure

at

but

also

Obesity for

Consuming

body

fat.

•

being

•

having

more

T wo

20%

a

food

ways

a

above

body

energy

person

the

than

can

required

be

identified

recommended

mass

index

increases

(BMI)

weight

greater

as

the

obese

for

his

than

quantity

of

people

those

is

calculated

using

the

following

to

lose

and

for

weight.

or

her

height

30. POINTS

formula:

1 body BMI

diabetes

wish

are:

KEY

BMI

with

who

mass

(in

Malnutrition

is

the

result

kilograms)

=

of

an

unbalanced

diet

2

height

(in

metres) where

There

is

an

obesity

epidemic

in

many

regions

of

the

World,

of

the

Caribbean.

The

causes

of

this

there

is

a

shortage

including nutrients

or

the

person

are: over-eats.

•

a

change

from

traditional

high

fibre

diets

to

‘Western’

diets

rich

in 2

fatty

food

and

refined

foods

that

contain

much

sugar

Deficiency

caused

sucrose)

and

•

increase

in

•

a

•

the

are

low

in

by

a

change

from

with

more

physically

money

active

to

to

more

spend

on

sedentary

food

the

of

walking

People

of

•

are

Avoid

heart

and

public

school,

disease,

for

high

foods

or

such

as

a

reduction

are

and

are

in

time

spent

at

Obesity

is

a

Eat

plenty

of

•

Eat

regular

risk

(high

(damage

uterine

to

developing

blood

joints),

cancers.

dietary

concentration

of

of

4

pressure),

Eat

meals;

many

People

People

a

with

with

strict

greatly

diabetes

DASH

diet,

should

such

as

and

follow

the

diet.

advice:

glucose

in

the

blood

foods,

avoid

fresh

sugary

fruit

foods

and

and

do

not

skip

QUESTIONS

vegetables.

drinks

especially

between

1

Define

the

protein

and

is

eating.

starchy

breakfast

in

condition

hypertension

meals.

•

a

person

SUMMARY

•

mineral(s)

overweight.

high

given

or

diet.

where

shops.

arthritis

bowel

the

and

hypertension

pressure

increase

after

or

obese

diabetes,

example

blood

that

immediately

transport

market

overweight

problems,

cancer ,

diabetes

and

work,

health

coronary

types

to

who

serious

cars

are

of

occupations 3

use

lack

fibre vitamin(s)

incomes

diseases

(especially

energy

deficiency

meals.

terms

malnutrition,

malnutrition,

diseases

and

obesity •

Eat

•

Try

•

low

to

Drink

and

in

foods,

avoid

not

with

addition

e.g.

eating

plenty

do

People

fat

of

fried

fluids

binge

low-fat

to

and

dairy

‘fast

keep

products

and

lean

meat.

food’.

hydrated;

2

drink

alcohol

effects

moderately

should

follow

the

advice

given

above,

reduce

3

should:

their

intake

of

sodium

(should

be

between

1500

a

increase

deficiency

Surveys

have

diseases.

people

in

the

that

Caribbean

Suggest

why.

intake

of

foods

rich

in

potassium,

e.g.

beans,

Summarise

the

dietary

advice

people

with

bananas,

is

given

to

vegetables

make

dairy

two

discovered

anaemia.

diabetes •

and

day)

that leafy

diseases

to

4 •

and

vitamin

mineral

have 2300 mg

causes

two

but

many •

the

of

deficiency

drink.

hypertension

Describe

sure

their

products,

diet

leafy

contains

foods

vegetables,

rich

bread

in

calcium,

fortified

e.g.

with

and

hypertension.

low-fat

calcium.

73

5.8

Respiration

Respiration LEARNING

constant

At

the

end

should

•

be

define

of

this

able

the

topic

to

you

to:

term

carry

distinguish

and

out

division.

cells.

of

small,

shown

This

all

of

of

the

is

computer-generated

image

of

a

time.

the

ATP

is

made

cell

structures.

0.002 mm

6O

fuels

energy

It

provides

used

is

stay

protein

to

alive

a

synthesis

provide

released

very

and

and

energy

gradually

in

in

a

reactions.

equation

energy

is

breakdown

of

glucose

in

6H

to

O

water

energy

+

energy

released

released

to

energy

ATP

reactions

each

glucose

released

ADP

+

chemical

catalyses

from

cells.

+

2

(ADP)

also

transferring

readily

the

is:

+

many

enzyme

energy

processes

in

dioxide

2

release

down

used

is

occur

These

used

to

in

reactions

convert

triphosphate

heat.

from

respiration

diffuses

with

which

adenosine

as

that

reaction.

the

easily

transfer

to

the

through

of

energy-

the

cell

and

energy.

mitochondrion

with

a

high

is

aerobic

energy

respiration

have

many

occurs

(Figure

5.8.1).

mitochondria.

respiration

anaerobic

respiration

oxygen.

shows

that

The

lactic

word

acid

glucose

Some

In

bacteria

humans,

exercise,

Oxygen

after

energy

sprinter,

Pryce,

may

reach

is

lactic

acid.

acid

when

glucose

respiration

without

in

animals

not

return

Oxygen

tissue

energy

they

released

respire

during

fast

without

bursts

oxygen.

of

weightlifting.

is

to

for

such

aerobic

therefore

released.

resting

required

exercise,

muscles

energy

+

anaerobically

and

does

Muscle

enough

from

anaerobic

acid

strenuous

the

released

lactic

lactic

finishes.

is

for

produced:

sprinting

hard,

needed.

there

Some

to

as

levels

immediately

repay

an

sprinting,

respiration

respires

glucose

to

oxygen

not

anaerobically

is

enough

supply

broken

all

so

down

the

that

to

Shelley-

The

relying

the anaerobic

exercise

is

respire

consumption

During

oxygen

as

energy

equation

→

produce

muscles

such

the

debt.

muscles

for

Each

using

Fraser

where

demand

long.

In

Jamaican

6CO

summarises

at

is

carbon

→

specific

Anaerobic

her

transport,

to

in

Cells

on

the

this

mitochondrion.

The of

→

diphosphate

good

breaks

oxygen

2

A

Some

consuming

it

+

respiration

ATP

Anne

are

the

need

equation:

chemical

equation

(ATP).

word

6

adenosine

is

fat

They

active

enzyme-controlled

oxygen

O 12

respiration.

these

and

as

respiration,

the

+

H 6

Most

such

respiration,

by

balanced

C

74

cells

cells.

respiration

aerobic

The

A

Glucose

During

glucose

5.8.2

living

for

aerobic

as

Figure

all

respiration.

In

5.8.1

in

energy

processes,

the

Aerobic

Figure

place

of

respiration

between

anaerobic

supply

cell

series

•

takes

OUTCOMES

respiration

in

lactic

acid.

extra

oxygen

absorbed

after

exercise

is

used

to

respire

When

yeasts

dioxide

as

respire

shown

glucose

Far

less

is

not

acid

and

of

and

measure

alcohol

with

a

to

in

the

in

carbon

of

a

hydrometer

of

sugar

as

a

lot

yeast

and

carbon

you

in

anaerobic

because

glucose

remains

in

lactic

energy.

little

access

growth

to

and

The

air,

it

produces

carbon

dioxide

5.8.3).

need

to

more

decrease

As

released

glucose

is

energy

Figure

produces

5.8.4).

of

bond

for

energy

This

products.

(see

This

of

with

energy

waste

decreases.

+

molecule

solution

release

(Figure

alcohol

dioxide

chemical

respiration,

As

make

respiration.

and

limewater

produced.

liquid

each

down

dioxide

with

carbon

from

form

to

anaerobic

the

+

they

equation:

aerobic

broken

kept

detected

density

alcohol

anaerobically

alcohol

be

is

word

released

alcohol

yeast

respires

To

is

this

compared

completely

When

can

→

energy

respiration

anaerobically

in

alcohol

measure

and

in

is

the

more

density

amount

alcohol,

is

the

measured

produced,

the

density Figure

of

the

fermenting

mixture

decreases.

Plants

also

respire

5.8.3

Limewater

detect

in

the

same

way

as

yeast.

This

happens

when

soils

get

flooded

the

is

no

air

in

the

soil

(see

used

to

presence

of

and carbon

there

is

anaerobically

1.3).

by

dioxide

anaerobic

produced

and

aerobic

respiration.

Biogas

Some

bacteria

respire

anaerobically

to

make

the

gas

methane

(CH

). 4

This

gas

biogas

human,

gas

is

can

animal

vented

energy

KEY

that

made

a

source

the

plant

used

use

is

one

of

in

waste

for

solid

available

energy.

Figure

and

cooking.

waste

often

5.8.5

kept

in

There

from

used

There

that

small-scale

are

anaerobic

are

also

sewage

to

are

filled

conditions.

large-scale

treatment

power

the

with

works.

treatment

The

biogas

The

works.

POINTS

ATP

is

the

Glucose

In

energy

between

convert

3

as

like

and

and

energy

2

used

generators

generators

1

be

is

respired

ADP

aerobic

currency

to

of

respiration

in

cells

cells;

and

to

ATP

is

used

to

transfer

energy-consuming

release

energy

that

is

processes.

used

to

ATP .

respiration

maximum

release

anaerobic

oxygen

of

this

occurs

energy;

where

less

oxygen

with

oxygen

energy

is

not

is

with

the

released

in

used.

Figure

5.8.4

Hydrometers

follow

4

Muscle

tissue

and

some

bacteria

respire

anaerobically

the

alcohol

5

Biogas

lactic

and

acid;

carbon

consists

of

yeast

respires

anaerobically

to

are

to

of

to ethanol

produce

used

production

by

yeast.

produce

dioxide.

methane

produced

by

bacteria

that

respire

anaerobically.

SUMMARY

1

Define

QUESTIONS

the

respiration

terms

and

respiration,

oxygen

aerobic

respiration,

anaerobic

debt Figure

2

Make

a

table

to

compare

aerobic

and

anaerobic

respiration.

5.8.5

This

small-scale

generator

biogas

provides

fuel

for

cooking.

75

5.9

Gas

You LEARNING

the

should

end

be

remember

of

this

able

topic

3.2.

gas

you

Unicellular

exchange

volume

to:

ratio

enough

•

state

the

gas

features

exchange

common

list

the

gas

exchange

Amoeba,

description

large

They

enough

dioxide

to

are

to

use

so

small

allow

leave.

their

and

Both

body

photograph

that

enough

gases

surface

their

oxygen

move

as

surface

to

their

area

enter

across

the

to

and

cell

of

these

protists

by

diffusion.

are

multicellular

animals.

They

too

use

their

body

surface

surfaces gas

exchange.

An

earthworm

10 cm

in

length

is

about

200

times

earthworms, longer

humans,

its

this

to

for of

from

like

surfaces

Earthworms •

is

creatures

surface.

carbon

membrane

all

Amoeba

surfaces

OUTCOMES in

At

will

exchange

fish

and

and

1500

times

thicker

than

Amoeba.

This

makes

it

much

flowering more

difficult

for

oxygen

to

diffuse

from

the

outer

layer

of

the

body

plants. to

the

centre

reverse

transport

gas

of

the

direction.

gases

exchange

animal

and

Therefore

and

there

(Figure

for

carbon

earthworms

are

many

dioxide

have

tiny

a

blood

to

diffuse

blood

in

system

vessels

the

to

(capillaries)

for

5.9.2).

Layer

of

watery

Cuticle

mucus

Epidermis

Capillary

Muscle

Figure

5.9.3

The

gills

catfish

of

this

have

giant

many

Inside

worm

gill

filaments. Figure

5.9.1

Gas

exchange

between

in

the

the

soil

occurs

Figure

5.9.2

There

air

and

earthworm’s

are

blood

capillaries

the

below

body

immediately

the

earthworm’s

epidermis.

surface.

The

gas

gills.

exchange

Water

covered

We

in

tiny

breathe

exchange

diffusion

of

flows

such

of

Alveoli

5.9.4

Each

gill

filament

by

that

full

are

provide

a

exchange

76

tiny

of

gill

leaves.

have

fish,

All

even

if

features

refresh

alveoli,

in

alveolar

the

in

gas

the

air

blood

into

air.

Our

and

gas

in

is

the

the

that

dioxide.

These

to

•

a

very

large

•

a

moist

•

walls

surface

the

exchange

and

contact

inside

the

exchange

of

surfaces,

the

internal

with

the

body.

oxygen

and

are:

area

for

the

diffusion

of

gases

gaseous

surface

(X

surface

so

that

gases

can

dissolve

before

diffusion

10).

that

are

thin

so

that

gases

do

not

are

diffusion

exchange

insects

are

deep

for

gas

of

surfaces

them

along

Gaseous

exchange

blood

other

tubes

plates

filaments

lungs.

Gas

the

the

with

gill

5.9.4).

our

lungs.

enclosed

adapt

in

into

breathing

are

leaf-like

and

air

the

exchange

they

tiny

between

5.9.3

common

the

that

has

and

plates

blood

huge

of

fish

(Figures

to

from

from

a

mouth

is

carbon covered

the

features

gills

surroundings,

Figure

out

in

dioxide

the

surfaces

and

of

the

plates

oxygen

shares

as

gill

occurs

of

carbon

surface

in

surface

into

have

to

diffuse

very

far.

Steep

concentration

gradients

for

oxygen

and

for

carbon

dioxide

are LINK

maintained

because

there

is:

See •

a

good

blood

supply,

bringing

carbon

dioxide

for

efficient

3.4

about and

absorbing

lots

of

to

remind

diffusion

breathing

that

constantly

supplies

fresh

oxygen-rich

air

When

of

waste

inspired

oxygen.

then

very

the

(see

and

Figure

Gas

Gas

diffusion

alveoli

air

exchange

exchange

there

is

in

air

in

air

stomata

spaces

air

two

in

of

reaches

the

layers

distance

those

1

one

the

the

watery

of

cells

between

capillary,

alveoli

lining

into

the

the

cells

which

it

of

contains

each

blood.

forming

are

all

a

A

where

the

is

walls

squamous

on

the

very

surface

are

either

the

side

of

different.

lot

alveolus

There

concentrations

and

a

of

cells

plants

leaves

spaces

allow

the

on

in

occurs

(see

on

movement

leaf.

both

They

all

the

cell

surfaces

exposed

to

4.3).

do

of

gases

not

in

form

a

and

gas

out

of

the

exchange

intercellular

surface

as

sides.

Figure

KEY

is

5.9.5).

intercellular

The

in)

dissolves

through

gradient

dioxide.

(breathed

Oxygen

diffuses

short

carbon

gradients.

and steep

removes

and

oxygen concentration

•

yourself

removal

Diffusion

of

oxygen

Diffusion

of

carbon

5.9.5

Gaseous

POINTS

Gaseous

dioxide

exchange

in

an

alveolus

exchange

is

the

diffusion

of

oxygen

and

carbon

LINK dioxide

between

the

surroundings

and

the

body

of

an

organism.

There

is

more

structure 2

Gaseous

to

3

the

exchange

size

Diffusion

of

an

surfaces

are

thin,

moist

and

large

and

4

Gas

exchange

SUMMARY

1

Describe

in

animals

are

maintained

by

blood

in

5.10.

at

3.3

You

to

All

in

plants

occurs

on

cell

surfaces

inside

EXAM

of

a

specialised

gaseous

exchange

surface.

Name

such

as

gaseous

mammals

exchange;

and

fish,

protists

have

such

these

Explain

for

why

gaseous

Amoeba

do

structures

in

mammals

and

Amoeba

does

not

have

a

Explain

4

Describe

a

at

why

the

night

We

and

walls

can

say

but

that

capilla ries

made

not.

no t

of

cell

walls

fish.

specialised

structure

remem ber

have

cell

plan t

walls ,

cells

but

exchange.

anim al

3

about

cells.

TIP

specialised

as

–

b

epithelial

Bewa re!

cells, a

look

leaves.

have for

also

yourself

movements.

features

vertebrates,

structures

should

remind

alveo li 2

alveoli

flow

QUESTIONS

the

of

relative

squamous

breathing

the

organism.

gradients

and

about

function

earthworms

gaseous

b

need

a

exchange

during

the

transport

that

day.

do

no t.

system.

occurs

Explain

cells

in

plants:

your

answers.

77

5.10

Breathing

The LEARNING

The At

the

end

of

this

topic

be

able

define

•

describe

lungs

the

are

are

term

the

breathing

describe

in

the

diaphragm,

intercostal

spongy

protected

a

sheet

the

breathing

of

organs

by

mechanism

muscle

abdomen.

downwards

•

system

the

situated

ribcage

within

and

the

the

thorax

backbone.

(chest).

The

diaphragm

to: is

•

exchange

you They

should

gaseous

OUTCOMES

and

When

and

fibrous

the

when

it

tissue

muscle

relaxes

separating

contracts

it

is

the

pushed

the

thorax

diaphragm

from

moves

upwards.

of

humans

role

of

the

ribcage

muscles

and

in

breathing.

Figure

5.10.2

An

X-ray

healthy

this

of

with

smoker

a

pair

lungs.

the

in

of

Compare

X-ray

of

a

5.11.

Trachea

Bronchiole

Figure

Left

Bronchus

5.10.1

The

pleural

cavity

membranes

rubbing

move

the

which

each

of

the

left

lung

The

in

tubes

the

Figure

system

or

two

are

air

airways.

nose

the

to

sacs

and

blood

which

air

fluid

passes

cords.

is

a

to

capillaries

moves

to

then

the

take

the

thorax.

is

many

for

an

efficient

reach

the

deep

the

The

the

to

breaths.

to

the

trachea,

trachea

which

small

called

contract

throat

enters

bronchus),

form

which

we

pleural

preventing

muscles

through

into

two

lubricant

when

Air

(singular

of

between

intercostal

and

branch

each

lies

especially

vocal

neck

and

This

The

bronchi

many

through

ribs.

the

continue

tiny

fluid

5.10.1).

the

contains

the

with

breathing,

through

into

alveolus

called

78

exchange

filled

mouth

passes

end

is

during

the

Bronchi

which

Structure

gas

against

which

branches

lung.

5.10.3

ribs

enters

larynx,

Bronchiole

(see

lungs

Air

Figure

The

lung

enter

each

bronchioles,

alveolus.

gas

alveoli

Around

exchange.

are

often

Breathing

1

The

in

muscles

flatten

the

(inspiration)

of

the

central

diaphragm

part

of

the

contract

and

diaphragm,

which Passage

is

made

are

of

tough

strong

lower

ribs

and

fibrous

connect

and

the

tissue.

to

the

sternum

These

of

air

muscles

backbone,

the

muscles

Ribs

2

The

external

the

internal

the

ribs

intercostal

intercostal

contract

(breastbone).

muscles

muscles

contract

relax.

Lungs

and

This

move

up

and

out

moves

The

volume

of

Ribcage

and

sternum

upwards

and

the

outwards.

chest

cavity

increases Diaphragm

3

These

movements

the

thorax,

the

lungs

The

air

so

increase

decreasing

the

the

volume

air

inside

pressure

Diaphragm

contracts

and

inside

moves

down

Front

4

pressure

atmospheric

nose

or

1

The

into

out

diaphragm

exerted

fibrous

2

pressure,

mouth

Breathing

inside

The

by

the

tissue

internal

the

so

the

lungs

air

is

less

moves

lungs

and

in

view

of

chest

Side

view

of

chest

than

through

they

your

Figure

5.10.4

Breathing

in

inflate.

(expiration)

muscles

relax

abdomen

and

pushes

the

the

pressure

Passage

central

upwards.

intercostal

of

air

Trachea

muscles

contract

and

External

intercostal

muscles

relax

the

Ribs

external

intercostal

muscles

relax

to

move

and

ribs

downwards

and

move

down

Lungs

the

in

inwards. Ribcage

3

These

movements

decrease

the

volume

inside The

the

thorax

so

increasing

the

air

pressure

volume

of

Diaphragm

inside

the

chest

cavity

relaxes decreases

the

lungs

and

Diaphragm

bulges

upwards

4

The

elastic

this

helps

tissue

around

the

alveoli

recoils

and

Front

During

alone

quiet

may

ribcage

during

to

or

be

move

air

shallow

moving.

when

out

of

the

breathing

Both

taking

the

the

diaphragm

diaphragm

deep

view

of

chest

Side

view

of

chest

lungs.

breaths,

and

for

Figure

5.10.5

Breathing

out

the

example

exercise.

SUMMARY

1

force

QUESTIONS

Distinguish

between

the

terms

breathing

and

respiration

KEY 2

Describe

from

the

the

pathway

atmosphere

taken

into

by

the

air

as

it

respiratory

system. 1

Y ou

could

draw

this

as

a

flow

chart

POINTS

moves

Breathing

of

3

Make

a

table

to

show

the

functions

of

all

of

the

gas

exchange

system

the

Figures

5.10.1

and

Inspired

Make

a

diagram

of

the

gas

exchange

labels

and

annotate

with

the

functions

different

in

and

out

air

enters

the

the

throat

nose

and

or

then

mouth,

the

passes

larynx,

the

vocal

which

cords.

The

air

passes

through

the

trachea,

bronchi

of and

the

air

system. 3

Add

of

5.10.3. contains

4

movement

labelled through

in

the

lungs.

the 2

structures

is

diagram.

bronchioles

to

the

alveoli,

where

gas

structures. exchange

occurs.

79

5.11

Smoking

Addicted LEARNING

At

the

end

of

should

be

•

the

state

this

able

tobacco

topic

describe

If

you

it

is

smoke

is

only

very

main

components

of

•

give

someone

up

the

who

habit.

smokes,

Smokers

explain

effects

of

tar

outline

prevented

with

by

but

smoke

it

is

one

why

to

people

become

Nicotine

to

smoking

the

effects

of

an

is

it

in

having

is

also

order

synapses

of

and

carbon

know

craving

that

that

to

in

another

physical.

function

our

smoke.

The

That

body

properly

nervous

craving

relies

on

because

system.

That

is

the

its

partly

drug

in

molecules

drug

is

nicotine

the

most

addictive

substances

known.

stimulant.

in

heart

alertness.

It

stimulates

rate

and

the

blood

Marijuana

release

of

pressure.

(ganga)

adrenaline

This

contains

a

gives

drug

an

leading

increase

that

has

the

nicotine

monoxide

on

effect.

It

has

a

calming

effect

and

may

induce

a

trance-like

the

state circulatory

a

increase

mental

opposite

and

also

cause

hallucinations.

system.

a

b

LINK

Cilia move Dust

Ciliated

These cells

cells

Synapses

drugs

will

a

on

in

nerve

you

have

airways

addicted

•

know

to

psychological

tobacco

smoke

the

or

hard

to:

and the

smoking

you

interact •

to

OUTCOMES

are

cells

tiny

(see

8.4).

including

nicotine

act

on

gaps

Many

heroin

our

make mucus

between

and

synapses.

Figure

5.11.2

a

Healthy

bronchus

lining

of

squamous

Cap

Damage Rubber

to

the

a

of

a

bronchus

long-term

of

a

smoker:

non-smoker,

the

ciliated

b

cells

Lining

are

of

a

replaced

by

cells.

lungs

tube

T ar

is

the

cools.

It

black

does

sticky

not

material

pass

into

that

the

collects

in

bloodstream.

the

T ar

lungs

as

irritates

smoke

the

lining

of

Bottle

the Contents

airways

the

epithelial

cells

to

produce

more

mucus.

of

This cigarette

stimulating

tends

to

accumulate,

narrowing

the

airways.

Smokers

cough

to

smoke:

make

Nicotine

this

material

move

to

the

back

of

the

throat

(Figure

5.11.1).

Tar

Carbon

T ar

monoxide

Carcinogens

causes

beating.

the

cilia

Mucus

on

and

the

the

cells

dust,

that

dirt

line

and

the

air

passages

bacteria

that

to

stick

stop

to

it,

Cotton

are

not

removed

bacteria

Figure

5.11.1

A

simple

Scientists

in

mixture

machines

80

blood

bronchi.

of

cells

The

mucus,

The

mucus

accumulates

congregate

bronchi

bacteria

attempt

to

cough

up.

This

with

this

condition

find

it

become

and

where

and

this

blocked

white

to

mimic

our

to

contents

smoke.

condition

difficult

sophisticated

behaviour

the

tobacco

the

lungs.

blood

happens,

with

cells),

is

chronic

which

bronchitis.

have

People more

analyse

White

phlegm

(a

the

smoking

machine.

smoking

multiply.

particularly

people

used

from

of

are

partly

blocked

(Figure

5.11.2).

to

breathe

as

the

bronchi

Particles,

bacteria

and

tar

reach

the

alveoli.

White

blood

cells

digest DID

a

pathway

Eventually

break

This

through

this

down

and

They

efficiently.

lining

weakens

condition

breath.

the

burst,

is

the

of

walls

reducing

emphysema,

cannot

Many

the

absorb

long-term

alveoli

of

the

the

have

so

area

leaves

oxygen

smokers

reach

alveoli

surface

which

enough

to

for

both

of

that

gas

as

an

that

for

carbon

these

T obacco

they

exchange.

gasping

remove

YOU

dioxide

conditions.

try

to

farmers

dry

Carbon

monoxide

red

blood

can

carry.

cells

of

smoked.

to

cases

is

of

be

as

to

the

kill

DNA

of

cells

and

take

leaves.

the

manufacturers

products,

such

volume

much

cancer

cause

of

promote

lining

divide

20

If

years

this

lung

Worse,

organs.

be

a

as

a

with

of

haemoglobin

oxygen

10%

dangerous

in

that

decrease

for

control.

there

people

cancer

airways.

of

before

occur

lung

changes,

the

out

is

not

pushing

part

If

a

more

of

are

discovered

against

the

tumour

removed

much

by

is

the

in

as

cigars

in

blood

the

pregnant

who

the

known

These

This

oxygen

women.

smoke

or

who

carcinogens

as

mutation,

mutations

growth

any

it

may

the

airways

tumour

is

may

discovered

surgery.

difficult

SUMMARY

to

is

cause

very

symptoms.

to

tar.

occur

the

slow

The

in

cells

and

cells

in

it

form

Figure

5.11.3

Lung

cancer

diagnosed

a

grow

to

occupy

a

large

If

the

treat

and

break

before

tumour

(Figures

blood

off

it

has

vessels

and

has

spread

spread,

5.11.3

to

spread

and

block

into

then

then

the

State

2

Smoking-related

healthy

with

X -rays.

the

lungs

in

X -ray

5.10.

them.

other

it

may

cancer

is

5.11.4).

components

of

tobacco

smoke.

diseases

are

often

classified

as

5.11.4

This

cancer

Discuss

the

whether

effects

of

or

not

smoking

this

on

is

the

true.

blood

gaseous

has

spread

self-inflicted through

Outline

this

often

taking

area

Figure

diseases.

is

by

QUESTIONS

1

3

and

make

cigarettes.

of

the

T obacco

leaves

Compare

tumour.

of

nicotine

insects

oxygen

permanently

the

particularly

lung

The

substances

grow

may

combines

produce

cancer

have

the

of

reducing

may

This

90%

These

so

There

transported.

Lung

transport

eat

harvest

them;

and

on

plants

insecticide

tobacco

Effects

KNOW?

bacteria.

much

people

or

the

the

lung,

vessels

and

blocking

airways.

exchange

system.

4

Explain

KEY

why

smokers

find

it

hard

to

give

up

their

habit.

POINTS

1

Nicotine

2

T ar

is

the

damages

production

Carcinogens

4

Carbon

cells

to

the

of

3

addictive

lining

mucus

in

reduce

the

of

and

smoke

monoxide

substance

the

in

tobacco

airways,

destroying

smoke.

stimulating

ciliated

cause

lung

cancer.

combines

with

haemoglobin

blood’s

oxygen-carrying

excess

cells.

in

red

blood

capacity.

81

Unit

SECTION

1

Which

5

1:

Practice

Multiple-choice

chemical

human

reaction

exam

questions

takes

place

inside

the

5

stomach?

A

sample

solution.

blue A

Cellulose

in

fibre

is

questions

digested

by

to

of

food

The

was

solution

purple.

tested

with

changed

Which

nutrient

biuret

colour

was

from

present

in

cellulase

the

food

sample?

enzymes.

2

B

Fats

C

Proteins

D

Starch

A

are

person

by

a

lack

digested

are

is

digested

digested

has

of

into

by

anaemia.

which

amino

by

protease

lipase

This

A

fat

B

glucose

C

protein

D

starch

acids.

enzymes.

enzymes.

could

be

caused

nutrient? The

A

rubber

sheet

in

this

model

of

thorax

B

iron

C

vitamin

C

D

vitamin

D

shows

diaphragm.

Questions

the

The

6

effect

of

Which

for

human

diagram

and

movements

is

needed

of

the

following

anaerobic

is

respiration

the

in

word

glucose

+

oxygen

→

of

the

answer

tube

equation

yeast? bell

A

to

7.

glass

3

the

calcium

carbon

dioxide

carbon

dioxide

jar

+

water balloon

B

glucose

→

C

glucose

+

D

glucose

→

alcohol

oxygen

+

→

lactic

alcohol

+

water

acid

rubber

4

Six

test

tubes

between

were

15 °C

contained

set

and

identical

up

65 °C.

at

Each

solutions

test

of

tube

starch

and

6 amylase.

The

time

taken

for

each

reaction

When

T est

was

recorded

tube

T emperature

in

this

the

rubber

sheet

is

pulled

downwards

to

the finish

sheet

temperatures

balloons

inflate.

This

is

because:

table.

1

2

3

4

5

6

15

25

35

45

55

65

A

air

pressure

in

the

balloons

B

air

pressure

in

the

bell

C

atmospheric

pressure

jar

is

increases

increases

greater

than

air

(°C)

pressure

Time

taken

135

75

30

15

95

in

the

balloons

185 D

atmospheric

pressure

is

less

than

air

(seconds)

pressure

7 The

optimum

temperature

When

the

45 °C

B

65 °C

the

rubber

A

air

deflate.

pressure

sheet

C

between

35 °C

and

45 °C

D

between

35 °C

and

55 °C

B

air

pressure

the

C

is

pushed

upwards

the

because:

balloons

is

greater

than

pressure

in

atmospheric

the

the

is

the

bell

jar

is

less

than

in

balloons

pressure

D

This

in

atmospheric

82

balloons

is: balloons

A

in

in

pressure

the

balloons

is

greater

than

balloons

contract

to

force

air

out

air

SECTION

8

Some

2:

Short

students

temperature

the

They

cells

source

as

a

oxygen

T able

questions

investigated

on

catalase.

determined

answer

used

the

of

activity

a

of

effect

the

The

reaction

T able

1

of

The

enzyme

suspension

catalase.

rate

produced.

10%

the

of

of

yeast

them

students

by

shows

for

collecting

their

student

reaction

the

a

with

is

samples

at

iodine

taken

shown

in

from

intervals

solution.

yellow-brown

samples

results.

took

mixture

colour

from

T able

each

each

and

The

to

tested

time

taken

appear

reaction

in

mixture

2.

1 T able

T emperature/

Volume

Time

°C

of

to

Rate

taken

2

of

pH

Time

taken

for

yellow-brown

3

oxygen

reaction/cm

obtain

colour collected/

oxygen/

of

seconds

per

to

appear/minutes

oxygen

3

cm

second

0

0

–

10

5

100

0.05

20

10

65

0.15

30

10

12

0.83

40

10

5

2.00

50

10

9

60

6

120

70

0

3

–

0

5

12

7

2

9

4

11

b

i

0.05

–

i

List

the

would

apparatus

use

in

this

that

Outline

the

would

have

to

the

results

given

that

follow

to

students

the

the

the

Describe

the

Calculate

the

Show

your

c

Plot

graph

d

Describe

rate

of

results

of

to

make

reaction

at

results

shown

in

i

students

obtain

the

(4)

Name

that

table.

the

parts

secrete

of

the

alimentary

results

State

reaction

at

50 °C.

what

amylase.

happens

of

alimentary

(2)

starch

to

the

end

digestion

in

f

Explain

i

the

State

results.

(2)

shown

by

your

graph.

of

this

a

Make

Suggest

two

investigation

in

could

which

be

ii

25

(2)

catalyses

the

hydrolysis

of

Write

a

word

equation

to

show

for

State

the

diagram

small

absorption

to

the

gas

intestine

of

exchange

food.

(6)

surfaces

A

catalysed

student

the

five

surfaces

the

are

of

reaction

using

amylase.

mixtures

solutions

the

ways

in

adapted

which

for

gas

these

exchange.

(4)

Explain

why

of

animals

require

a

continuous

oxygen.

(3)

the

effect

The

of

of

fish

starch.

amylase.

investigated

activity

starch

by

of

(2)

Total reaction

show

is

humans.

Compare

supply a

annotated

in

marks

c Amylase

fully

villus

and

the

improved.

Total

9

i

(1)

ways

a

a

adapted

b

investigation.

ii

marks

(4)

(4)

limitation

15

(5)

results.

one

the

canal.

(2)

how

e

canal

(4)

10 the

pH.

the

working.

of

table

your

Total

a

a

each

(3)

products

b

rate

table.

ii in

student’s

(5)

investigation.

method

the

0

c

ii

Use

showing

ii

a

–

of

student

amylase

15

marks

(2)

pH

and

different

on

made

pH.

Further

and

on

practice

examples

the

questions

can

be

found

accompanying

CD.

83

6

Transport

6.1

Transport

Tiny LEARNING

unicellular

multicellular

At

the

end

should

be

of

this

able

topic

thin

you

bodies

dioxide.

to:

they

•

explain

why

materials

transported

in

that

animals

are

•

and

the

more

the

by

This

of

an

to

2a,

alkali

you

as

should

the

For

could

the

plot

the

of

horizontal

the

the

ratio

length

cubes

given

case

cannot

axis

axis,

of

column

1,

1.2,

Remember

the

area

to

are

diffusion

not

for

have

and

flat

flat,

carbon

and

transport

thin;

of

great

to

diffusion

becomes

as

a

too

oxygen

about

will

alone.

indicator.

into

dilute

as

the

changes

small

surface

demonstration

pH

distribute

(think

the

throughout

distance

from

the

your

toe)

diffusion

a

bulk:

for

help

Agar,

The

relative

gaseous

a

you

jelly

is

cut

hydrochloric

acid

colour.

diffuses

The

to

special

this

body

mass

understand

jelly,

into

acid.

into

time

to

to

exchange.

is

cubes

The

the

of

is

a

difficulty

with

different

colour

blocks.

takes

the

mixed

of

the

pH

Eventually,

the

measurement

long

the

acid

takes

to

diffuse

to

the

centre

of

the

block.

The

shows

some

students’

results

for

this

investigation.

you

1)

4

6.1.1

Diffusion

for

different

surface

area:volume

ratios

or

(in

1.5,

scale

calculated

and

cubes

2,

of

Surface

Volume/

Ratio

of

Time

taken

for

block

3 3

area/m

mm

surface

to

change

colour

area:volume

acid/seconds

in

the

1

6

1

6:1

8

2

24

8

3:1

26

3

54

27

2:1

43

4

96

64

1.5:1

65

5

150

125

1.2:1

112

6

216

216

1:1

160

the

and

the

surface

the

volume

area

The

20

ratios

time

times

taken

The

ratios

decrease

given

in

in

as

size:

the

the

has

a

ratio

of

of

6:1,

cube

has

a

of

substances

oxygen

they

surface

the

of

centre

the

of

smallest

the

largest

cube

is

cube.

and

by

glucose

diffusion

to

cells

is

far

not

an

efficient

removed

from

way

the

of

places

are

absorbed

into

the

body.

whereas

ratios

ratio

of

of

surface

area

to

volume

given

in

the

table

decrease

as

area

cubes

increase

in

size.

This

is

because

the

volume

of

the

cubes

the

increases largest

to

centre

cubes

the volume

diffuse

the

smallest

The cube

to

to

the

where

increase

acid

than

and

getting

table

for

slower

Movement

volume.

much

more

each

time

than

the

increase

in

the

surface

area.

1:1.

Your

84

organisms

on

oxygen

FOCUS

between

to

of

each

(column

in

plot

students

surface

of

some

correctly.

STUDY

The

transport

rely

increased

2

6).

and

bodies.

too

big

placed

side/mm

and

for

multicellular

with

on

changes

block

how

Cube

which

5.9),

tapeworms,

plot

T able

side

(see

and

vertical table

axis.

on

and

are

surface

and

indicator

of taken

their

efficiently

practical

whole

time

Amoeba

flatworms

diffusion

and

come

your

body

relying

sizes

FOCUS

question

on

most

within

relying

function

the

rely

bulky

distances

lungs

•

In

and

problems

body

plants.

STUDY

as

as

transport

T wo

the

such

such

multicellular

need

systems

state

organisms,

However,

are

substances

organisms

•

organisms,

OUTCOMES

body

is

much

bigger

than

these

cubes,

so

your

own

surface

area

to

volume

ratio

will

area

to

volume

ratio

we

be

even

smaller.

With

such

a

small

surface STUDY

from

the

great

body

and

surface

there

is

not

cannot

to

cells

rely

deep

enough

on

in

diffusion

the

surface

body.

area

to

to

transport

The

distances

absorb

FOCUS

oxygen

enough

are

too

oxygen.

Another

absorb

surface

Transport

in

flowering

plants

and

Look

mammals

do

T able

6.1.2

Feature

Transport

of

Nutrients

transport

in

flowering

plants

systems

and

plants

Carbohydrates:

Others:

of

water

In

Transport

of

respiratory

gases

amino

xylem

(supply

dioxide

spaces

Transport

Fluid(s)

T ubes

of

hormones

In

transported

used

in

transport

the

sucrose

acids,

for

moving

fluids

is

of

Process

prevent

flow

of

of

ions

sealing

loss

of

oxygen

and

and

sap,

Xylem

vessels,

carbon

through

air

wounds

to

phloem

phloem

the

Yes

(8.2)

sap

phloem

In

The

table

amino

why

we

exchange.

–

glucose

acids,

mineral

fatty

ions

blood

(6.4)

oxygen

and

the

blood

acids,

(6.4)

carbon

dioxide

(9.3)

sieve

tubes

Arteries,

capillaries

–

transpiration

–

pressure

pull

flow

(6.6)

Heart

pumps

and

blood

veins

(6.2)

(6.3)

(6.8)

Faster

seal

of

callose

phloem

sieve

(a

carbohydrate)

Blood

clotting

(6.4)

tubes

POINTS

QUESTIONS

shows

information

about

three

spherical

organisms:

Transport

systems

substances

Feature

Spherical

2 B

Mammals

1

and

flowering

C

plants

2

3

need

because

2

area/mm

organisms.

organisms

A

Radius/mm

move

around

multicellular

Surface

out

gas

body

Blood

1

1

find

for

our

skin.

(6.4)

KEY

SUMMARY

have

6.8)

Production

to

to

it

not

(4.3)

Slower

fluids

Others:

In

diffusion

cells)

xylem

Xylem

fluids

of

by

and

Phloem

Rates

we

Carbohydrates:

mineral

(6.6)

Xylem

(6.6,

Mechanism

8.8

use

vitamins,

the

No

at

not

that

do

Mammals

(6.8)

Transport

is

we

through

mammals

Flowering

transported

reason

oxygen

12.57

50.27

113.10

4.19

33.51

113.10

great

transport

distances

for

are

transport

throughout

the

to

body

systems

too

occur

by

3

Volume/mm

diffusion.

a

State

which

organism

has

the

highest

surface

area:volume

3

ratio.

b

are

Explain

A

Oxygen

may

why

B

and

C

may

need

a

transport

system,

blood

whereas

move

not.

and

in

by

a

Plot

b

Use

a

line

graph

of

the

results

in

T able

diffusion

graph

you

have

drawn

to

explain

why

a

transport

Flowering

ions

and

dioxide.

plants

organic

How

do

spaces

in

plants.

Carbohydrates,

other

organic

system. nutrients,

3

but

through

humans 4

need

air

dioxide

the

6.1.1. flowering

the

in

mammals,

intercellular

2

carbon

transported

have

a

transport

substances,

these

gases

but

system

not

reach

for

cells

for

water,

oxygen

in

the

mineral

and

carbon

leaves?

hormones

in

both

mineral

are

mammals

flowering

ions

and

transported

and

plants.

85

6.2

Transport

The LEARNING

At

the

end

should

be

transport

of

this

able

describe

topic

you

the

heart

through

the

heart

in

the

in

one

define

the

term

and

functions

capillaries

of

and

how

the

structure

capillaries

related

back

in

to

the

systemic

and

their

the

would

the

blood

of

in

all

be

better

animals

insects

with

to

say

system

blood

have

such

have

blood

where

you

circulation

the

not

in

veins.

through

body.

6.2.1

started.

–

T o

from

The

We

the

prove

the

two

deoxygenated

pulmonary

circulation

the

aorta

and

circulation

the

veins

–

and

then

have

a

heart

this,

double

twice

follow

lungs,

around

the

circulations

the

are:

arteries

to

blood

the

flows

lungs

from

and

the

back

as

oxygenated

to

the

blood.

oxygenated

blood

flows

from

the

heart,

other

back

arteries

to

heart

to

all

the

through

other

the

organs

vena

cava

as

blood.

is

also

is

as

blood

the

described

remains

as

inside

a

closed

as

circulatory

an

in

large

in

blood

during

its

system

journeys

body.

blood

blood

open

vessels

that

vessels.

crabs

blood

an

and

neck

Not

vessels,

and

circulation

spaces

in

Lungs

the Jugular

body,

by

from

functions.

circulation

within

animals

flows

the

Figure

Head

flows

heart

away

KNOW?

circulation

enclosed

which

circulation

pulmonary

body

throughout

the

pumped

veins

because

It

is

travels

of

The

YOU

in

towards

diagram

to

through

deoxygenated

DID

that

Blood

veins

of

is

the

pulmonary

through

arteries,

blood

arteries,

•

explain

of

vessels.

system

heart

•

system

complete

around

heart,

the

consists

blood

double •

state

and

of

humans

circulatory

•

humans

system

circulatory

system

•

a

arteries

circulatory

to:

blood

system

in

humans

OUTCOMES

during

•

system

in

vein

Carotid

artery

vessels.

Pulmonary

Pulmonary

artery

vein

LINK

Left

Squamous

cells

are

very

thin.

Vena

Right

cava

atrium

atrium

They

line

the

capillaries.

alveoli

They

are

as

well

thin

so

as

Aorta

that Left

Right

the

diffusion

side

to

the

distance

other

is

from

very

one

ventricle

ventricle

Liver

short. Hepatic

Diffusion

distance

is

is

more

short

efficient

(see

if

the

Hepatic

vein

artery

6.1).

Stomach

and

Hepatic

intestines

STUDY

portal

FOCUS

vein

Intestinal

Blood

is

red.

Oxygenated

blood Renal

is

bright

red;

Renal

deoxygenated vein

artery Legs

blood

is

dark

convention

represent

doesn’t

blood

is

red.

to

It

use

is

a

blue

to

deoxygenated

mean

that

actually

blood.

It

deoxygenated

blue.

It

isn’t. Figure

86

6.2.1

The

human

circulatory

system

with

names

of

the

major

blood

vessels

Blood

The

vessels

walls

of

arteries

and

veins

are

made

of

three

different

Thick

tissues:

outer

layer

•

squamous

cells

•

muscle

tissue

•

fibrous

tissue

that

that

form

a

smooth

contains

elastic

lining

tissue

and

collagen

fibres.

Small

The

walls

of

capillaries

do

not

have

muscle

or

fibrous

tissue;

they

space

which

only

composed

of

the

squamous

and

6.2.1

The

structure

and

blood

flows

cells. Thick

T able

through

are

function

of

blood

layer

elastic

of

muscle

fibres

vessels Figure

6.2.2

An

artery

layers

Blood

Relationship

between

structure

and

with

cut

the

outer

away

function

vessel

Artery

•

Blood

(Figure

•

Elastic

flows

away

from

the

heart

at

high

Two

pressure

are

tissue

in

the

walls

withstands

surges

in

outer

layers

thinner

than

blood arteries

pressure;

6.2.2)

•

it

stretches

blood

pressure

Blood

is

than

it

delivered

left

the

and

to

recoils

organs

at

to

a

maintain

pressure

the

slightly

less

heart through

•

Walls

have

withstand

Vein

•

Blood

(Figure

•

Vessels

thick

high

flows

layers

blood

towards

expand

to

of

muscle

and

fibrous

tissue

to

blood

pressures

the

take

heart

at

low

increasing

elastic

pressure

volumes

of

•

As

during

blood

•

Walls

they

•

Capillary

by

have

do

Blood

6.2.3

A

vein

exercise

pressure

prevented

fibres

blood, Figure

e.g.

6.2.3)

which

flows

thin

not

low,

layers

have

flows

is

semi-lunar

to

backflow

valves

of

muscle

withstand

between

at

arteries

of

blood

intervals

and

high

and

fibrous

blood

veins

is

along

veins

tissue

as

pressures

at

low

pressure

(Figure

6.2.4)

•

Oxygen

•

Water

and

carbon

dioxide

diffuse

through

the

Red

walls

blood

inside

pass

and

solutes,

across

the

such

walls

as

into

glucose

tissue

and

fluid

amino

a

cells

capillary

acids,

surrounding

the

cells

•

Walls

are

between

thin

the

so

there

blood

is

and

a

short

the

diffusion

tissue

distance

fluid Figure

KEY

6.2.4

A

capillary

×

2000

of

the

to

In

a

double

heart

circulation

twice

in

one

system,

complete

blood

travels

circulation

of

through

the

the

Blood

flows

pulmonary

from

the

circulation

heart

and

to

the

from

lungs

the

and

heart

to

back

the

in

detail

and

back

in

the

systemic

Blood

heart

flows

in

away

veins

from

and

the

through

have

have

thin

exchange

thick

walls

as

vessels

walls

blood

and

to

heart

in

tissues

arteries,

in

the

is

cut

up

red

away

blood

cells

QUESTIONS

rest

of

the Explain

towards

very

is

thin

one

how

blood

direction

circulatory

the

in

flows

the

system.

capillaries.

withstand

pressure

have

show

Part

circulation.

2

Arteries

wall.

the

in

4

the

make

body.

1 body

3

that

inside.

SUMMARY 2

show

cells

POINTS the

1

magnified

to

high

low;

pressure;

capillaries

walls.

veins

are

Relate

the

artery,

vein

the

structure

and

function(s)

these

blood

of

the

capillary

of

each

to

of

vessels.

87

6.3

The

The LEARNING

the

should

end

be

of

this

able

topic

for

you

describe

the

the

heart

major

structure

valves

blood

•

explain

how

the

to

the

lungs

and

the

body

during

muscle

a

hundred

need

a

heart

of

the

and

contracts

can

four

on

the

then

our

right

vessels

functions

describe

consists

to

and

almost

flow

side

of

or

pump

through

by

the

blood

to

the

entirely

can

of

cardiac

contract

about

without

tiring.

more

to

the

70

muscle

times

a

tissue.

minute

the

around

blood,

vessels

pumps

and

rest

of

The

blood

the

the

body.

applying

to

overcome

heart

the

The

pressure

is

a

the

heart

to

it.

pressure

‘double

lungs

and

The

blood

exerted

pump’:

the

left

the

side

body.

heart

move

to

what

blood

the

atmosphere.

heart

blood

the

to

rest

To

of

From

one

that

years

‘squeezes’

bodies

pumps •

heart

specialised

to:

including

chambers,

is

up

We

•

human

OUTCOMES This

At

heart

Aorta

happens

heart

body

body

Vena

cava

(main

beat.

To

vein)

right

lung To

Semi-lunar

left

lung

valves Pulmonary

veins

From

Left

Valve

lungs

atrium

tendons

Atrioventricular

valve

Figure

6.3.1

The

heart

front

of

viewed

the

from

the

Vena

body

cava

Left

ventricle

Right

ventricle

From

body

Septum

Figure

The

septum

mixing

heart Figure

6.3.3

A

heart

dissected

inside

and

the

of

the

to

base

of

left

the

of

heart

separates

the

are

two

two

and

halves

of

the

oxygenated

chambers.

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upper

heart.

blood.

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On

chamber

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each

is

the

side

the

of

the

atrium.

show

empties

into

the

atria

from

veins.

When

each

atrium

contracts

ventricle

aorta

it

pumps

muscular

higher

88

The

deoxygenated

there

Blood the

6.3.2

blood

walls

into

than

pressure

over

a

ventricle.

the

a

atria

great

as

The

ventricles

they

have

distance.

to

have

pump

much

the

more

blood

at

Between

These

each

valves

atrium

when

pulmonary

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The

is

that

Heart

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the

is

not

atrium

heart’s

instruct

The

a

has

to

back

pump

the

atrioventricular

back

blood

to

are

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the

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around

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the

around

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left

of

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heart

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to

some

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and

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pacemaker.

the

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ventricle.

has

body

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than

spongy

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texture.

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then

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chamber

cells

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when

gets

by

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brain.

cardiac

send

out

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to

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and

In

muscle

the

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cells

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act

chamber

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when

is

systole,

6.3.4a).

to

higher

atria

relax

arteries

the

when

Figure

the

pulses

of

as

electricity

that

contract.

contract.

squeezes

When

the

the

blood

muscle

out.

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then

Figure

of

the

to

between

blood

in

ventricles

6.3.4b).

The

it

fills

up

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blood

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again.

contract.

muscles

contract

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so

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atria

pressure

and

(see

the

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heart

the

The

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force

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into

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force

pressure

the

ventricles

ventricles

in

open

against

blood

the

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due

them.

out

into

ventricles

The

the

closes

Figure

6.3.4

The

the

the

systole

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c

each

systole

the

valves.

when

right

the

and

base

semi-lunar

than

valve.

right

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wall

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lungs,

into

contract.

there

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through

an

ventricles

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action

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much

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and

blood

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right

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blood

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prevent

left

This

atrium

prevent

atrioventricular

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to

prevent

blood

flowing

back

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changes

heart

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during

occur

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in

heart

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to

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of

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in

pressure

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in

fi ll

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Figure

also

right

blood

arteries

(main

blood

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the

semi-lunar

to

flow

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valves

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from

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at

the

base

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right

left

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of

ventricle

to

the

SUMMARY

in

diastole.

the

left

vena

atrium

1

Explain

why

2

Describe

cava

in

the

(main

vein).

by

pulmonary

the

6.3.4c).

the

blood

as

need

a

heart.

pathway

it

flows

taken

through

heart.

Explain

the

between

difference

diastole

and

systole.

POINTS

3

1

we

Deoxygenated

2

KEY

QUESTIONS

artery).

during

atrium

returns

the

The

heart

consists

of

two

muscular

pumps

divided

by

The

heart

is

sometimes

a described

as

a

‘double

pump’.

septum.

2

Each

side

has

two

chambers:

an

atrium

and

a

4

3

Ventricles

contract

atrioventricular

blood

flows

in

to

valves

one

force

and

blood

two

direction

into

arteries;

semi-lunar

through

the

The

right

ventricle

circulation;

circulation.

the

pumps

left

blood

ventricle

into

pumps

the

what

Explain

how

blood

two

valves

ensure

this

means.

one-way

through

the

flow

heart

of

is

achieved.

that

heart. 5

4

Explain

ventricle.

pulmonary

blood

into

the

systemic

Make

of

the

a

large

labelled

human

system

showing

included

in

diagram

circulatory

6.2

all

and

the

organs

6.3.

89

6.4

Blood

LEARNING

At

the

end

should

be

Blood

is

heart.

As

the

of

this

able

topic

are

you

the

to:

list

the

components

of

blood

exchanged

lungs

respiring

•

fluid

that

is

pumped

around

the

circulatory

system

by

the

OUTCOMES flows

with

there

is

tissues

through

the

surrounding

gaseous

there

capillaries

is

exchange

exchange

in

the

tissues.

with

with

We

the

the

organs,

have

air

cells

in

seen

the

that

substances

that

alveoli.

require

in

In

oxygen

the and

need

to

have

their

carbon

dioxide

removed.

blood

Blood •

state

the

function

of

is

a

tissue

that

consists

of

cells

and

fragments

of

cells

each suspended

in

plasma

(Figure

6.4.1).

component

•

explain

red

how

blood

the

cells

phagocytes

structure

of

(erythrocytes),

and

lymphocytes Plasma

are

related

to

their

functions

3

Plasma

10 cm

•

explain

how

•

defence

blood

define

against

is

the

system

terms

and

liquid

•

nutrients,

•

wastes,

•

blood

•

hormones,

part

of

such

of

blood

water

as

with

glucose,

(55%

of

blood

chemicals

amino

volume).

dissolved

acids,

lipids,

in

it:

vitamins

involved and

in

–

consists

mineral

ions,

e.g.

sodium

and

chloride

ions

disease

immune

natural

immunity

such

as

proteins,

urea

such

such

as

and

as

carbon

dioxide

albumen

insulin,

and

glucagon

antibodies

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3

5 cm

White

Red

Figure

T able

6.4.1

Figures

Figure

6.4.2

In

this

see

phagocyte

Figure

T ype

Red

and

6.4.3

of

to

a

blood

lymphocyte.

identify

blood

blood

photograph

red

cell

cell

them

you

cells,

Blood

shows

6.4.2

and

and

the

blood

its

cells

components

features

of

the

blood

cells

you

can

see

in

6.4.3.

can

with

800).

T able

6.4.1

Features

Relationship

•

Small

Can

•

Shape:

•

No

•

Cytoplasm

cell

biconcave

nucleus,

no

disc

change

is

•

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•

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•

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full

of

and

fit

easily

and

function

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space

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fill

with

haemoglobin

to

haemoglobin

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nucleus

small

mitochondria

vacuoles

oxygen

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gaps

in

and

helps

the

carbon

cells

dioxide

leave

capillary

blood

through

walls

and Vacuoles

small

shape

structure

capillaries

cell

with

between

mitochondria

transport

many

platelets

cells

More

Phagocyte

and

a

Compare

(×

6.4.1

blood

contain

enzymes

to

digest

bacteria

containing

enzymes

Lymphocyte

•

Small

cell

•

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quantity

mitochondria

90

When

of

cytoplasm

with

few

activated

cytoplasm

that

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during

enlarges

made

of

to

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infection

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protein

(see

the

antibodies

6.5)

Defence

against

disease Phagocyte Red

Blood

the

is

involved

formation

pathogens

This

1

is

are

interact

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blood

the

blood

Platelets

that

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enter

how

in

clots

body,

clots

small

with

at

the

site

specialised

are

cell

pathogens

from

of

a

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damaged

white

blood

the

blood

cells

body

vessel.

destroy

blood

cells

by

If

them.

formed:

fragments

calcium

ions

in

which

the

release

plasma

to

substances

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prothrombin.

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2

Inactive

prothrombin

3

Thrombin

changes

into

the

active

enzyme

Figure

then

catalyses

the

conversion

of

the

soluble

6.4.3

A

drawing

into

fibrin,

an

insoluble

protein.

photograph

the

(×

4

Fibrin

cells,

Blood

the

which

of

in

to

Phagocytes

cells

in

the

enzymes.

Blood

or

skin,

form

engulf

immune

invade

us

new

skin

are

cells

of

the

that

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open

cells

at

the

that

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in

all

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the

where

and

specifically

invade

List

b

What

in

the

part

they

target

discussed

the

blood.

digested

by

cytoplasm.

non-specific

of

our

form

the

in

are

body ,

defence

our

natural

pathogens

that

6.5. 6.4.4

Red

blood

in

meshwork

a

the

components

percentage

component

of

consists

Make

of

the

total

volume

does

Blood

is

blood

cells,

a

c

State

What

of

cells

and

fragments

of

cells

suspended

in

drawing

of

each

type

of

cell

found

in

2

(phagocytes

of

red

blood

function

the

of

each

and

suspended

liquid

Red

fragments

of

to

cell.

cells

called

and

what

is

and

lymphocytes)

blood

filled

are

white

occupy?

labelled

the

composed

each

blood.

b

fibrin

2000)

blood.

plasma.

a

trapped

of

POINTS

cells

Blood

cells

QUESTIONS

1

2

800)

divide

KEY

a

to

6.4.2

a

(×

1

Figure

prevents

is

the

from

they

other

are

and

there

Figure

SUMMARY

in

blood

epidermis

phagocytes

and

one

damage.

vacuoles

These

and

blood

When

bacteria

attract

are

of

of

the

vacuoles

inherit

They

loss

If

from

similar

6.4.4).

base

phagocytes

we

platelets

wounds.

repair

invasion.

inherited.

Figure

the

to

trap

pathogens.

into

action

to

restrict

stored

defences

not

to

chemicals

defeat

The

scab

destroy

bacteria

the

fibres

through

stem

system

are

a

the

enzymes

may

of

wounds

release

clotting,

immunity.

form

and

engulf

The

defences

to

seals

area

Phagocytes

meshwork

pathogens

the

mitosis

a

dry

clotting

entry

wound

by

forms

made

protein a

fibrinogen

Platelets

thrombin.

with

in

cells

platelets

plasma.

are

haemoglobin

transport

oxygen;

phagocytes

contain

enzymes

digest

their

to

bacteria;

function?

lymphocytes

3

Explain

how

each

of

the

cell

types

you

have

drawn

in

question antibody

2a

is

adapted

to

its

Outline

how

blood

defends

the

body

against

Natural

all Make

a

flow

chart

diagram

to

show

what

immunity

happens

forms

inherit;

of

defence

blood

to

that

clotting

we

and

during

phagocytosis blood

refers

disease. the

5

molecules.

function.

3

4

produce

are

examples.

clotting.

91

6.5

Immunity

If LEARNING

you

while

At

the

end

should

be

of

this

able

topic

you

and

If

to:

define

the

term

and

an

infection,

have

within

the

get

•

have

such

as

the

common

cold,

you

will

be

ill

for

a

OUTCOMES

same

the

a

a

variety

week

strain

same

or

of

of

two

the

symptoms.

you

will

common

symptoms.

Y ou

will

be

will

back

cold

not

Y ou

to

virus

be

ill.

then

your

is

to

normal,

invades

This

begin

again,

another

feel

better

healthy

you

will

role

of

self.

not

the

artificial immune

system:

to

provide

highly

effective

defences

against

specific

immunity pathogens.

•

outline

how

system

the

provides

Lymphocytes

are

responsible

for

this

specific

immune

explain

is

used

how

in

recognise

antigens

on

pathogens bacteria

•

immunity.

defences

Lymphocytes

against

specific

and

release

specific

antibodies

vaccination

the

control

communicable

of

(infectious)

diseases.

Antibodies

attach

LINK to Antibody

The

reason

infection

the

are

is

body’s

HIV

is

that

defence

diseases.

it

a

for

bacteria

that

much

against

See

on

molecules

serious

destroys

lymphocytes

responsible

our

such

antigens

of

infectious

10.3. Phagocytes

towards

are

attracted

bacteria

and

engulf

them Small

vacuoles

contain

EXAM

T ake

the

TIP

care

wo rd s

with

with

An

chem ical

antib

.

is

a

to

produc e

Antib od

6.5.1

Lymphocytes

are

pro tei ns

destro y

toxin s

Y ou

are

born

lymphocyte.

antibodies

and

destroy

that

make

it

easier

for

types

of

phagocytes

them.

with

These

a

very

cells

large

are

number

specific

to

of

different

different

surface

chemicals,

neut ralis e known

as

antigens.

that

and

other

These

are

‘cut

it

pathogens.

When

a

found

on

pathogen

the

surface

and

antigens

enters

the

of

bacteria,

body,

viruses

phagocytes

some up’

display

to

lymphocytes.

Those

lymphocytes

that

produc e. recognise

•

Some

so

the

of

that

blood.

92

bacteria

(pois onou s

chem icals )

bacteri a

engulf

help

pathog ens.

Antit oxins

the

that

secrete

ies to

to

within

stim ulates

Figure

odies

digested

this

antig en

lymph ocytes

are

vacuoles

begin

in

that

Bacteria

all

food

that

‘anti’

unit.

enzymes

antigens

these

they

by

lymphocytes

can

These

divide

secrete

proteins

mitosis

become

protein

are

and

multiply.

bigger

molecules

antibodies.

and

into

fill

with

lymph

cytoplasm

and

into

the

•

Some

to

•

antibodies

clump

stick

together

as

Antitoxins

are

products

bacteria,

of

diphtheria,

The

Many

are

pathogens

When

pathogens

The

first

This

is

same

are

pathogens

combine

those

them

invade

find

you

you

so

that

that

takes

This

produce

a

with

the

cause

they

week

a

cells

and

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fallen

is

much

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and

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tetanus

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so

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them

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and

effect.

and

during

so

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the

the

to

this

time

to

first

in

so

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you

are

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the

is

very

slow.

infection

unlikely

many

pathogen.

body

infected

cells.

infection

the

other

for

them

other

the

that

specific

remain

looking

destroy

spread

fast

infection,

body

response

during

recognise

the

infection,

The

faster;

antibodies,

During

patrol

infected

have

that

cells.

to

reproduce

have

pathogen

our

activated

they

produced

not

as

of

6.5.1.

that

such

antibodies

cannot

time

why

symptoms.

are

antibodies

of

surface

ill.

lymphocytes

cells.

the

Figure

neutralising

production

people

to

in

to

by

the

have

any

lymphocytes

Some

of

these

memory

do

cells.

A

Figure

6.5.2

Vaccination

of

second

invasion

of

the

same

pathogen

stimulates

the

large

number

against

memory

for

cells

many

to

respond

years,

perhaps

immediately.

a

lifetime,

Memory

giving

us

cells

remain

long-term

in

the

is

protecting

a

key

part

populations

of

infectious

diseases.

body

immunity

KEY

POINTS

Vaccination

1

It

is

possible

to

promote

the

same

type

of

immunity

Immunity

resist

without

having

to

be

ill.

Artificial

immunity

may

is

the

ability

to

artificially

be

achieved

the

spread

of

an

by infection.

injecting

a

antigens

taken

vaccines

contain

against

begin

a

vaccine

that

from

stimulate

antigens

measles,

contains

the

surface

immunity

for

several

mumps

vaccination

to

live

of

pathogens,

pathogens

just

one

diseases.

and

rubella.

programme

It

early

(Figure

specific

For

to

6.5.2).

Some

2

infectious

diseases

that

can

be

against

children

the

life-threatening.

risk

require

booster

injections

to

ensure

that

there

against

cells

an

Countries

in

the

invasion

have

body

of

a

to

mount

a

rapid

and

are

effective

specific

Vaccines

to

vaccines

Some

vaccines

such

are

as

programmes

protect

only

vets

given

and

whole

This

population,

happens

everyone

(or

eradicated

because

nearly

from

everyone

to

to

protect

against

travellers

medical

including

staff.

their

and

common

to

special

Vaccination

people

pathogens

everyone)

the

are

as

polio,

are

world

likely

is

in

is

have

who

no

vaccinated.

this

way

and

cannot

place

to

categories

used

to

of Define

the

terms

to

be

eradicated

in

the

has

and

vaccination

if

2

Distinguish

between

a

and

been

infectious

near

immunity,

protect

vaccinated.

reproduce

Smallpox

other

be

QUESTIONS

specific

non-specific

diseases, (see

6.4)

future. natural

and

artificial

(see

6.4).

FOCUS

3

Artificial

immunisation

is

provided

in

two

ways.

Explain

immunity

is

given

by

vaccination;

short-term

immunity

injecting

antibodies

that

are

prepared

from

the

isolated

from

blood

may

Discuss

the

importance

of

plasma

vaccinating blood

immunity

gained.

is

4 by

how

Long-term be

of

immunity

diseases.

immunity

given

artificial

populations.

b

STUDY

an

diseases.

immunity

such

pathogens.

defence

vaccine the

to

act

enough

1 people,

that

pathogen.

vaccination

included

activated

promote

SUMMARY The

are

antibodies

of

against

memory

infection,

Many way

vaccines

an

produce

3

catching

During

lymphocytes

protects

that

reduce

or

Others

MMR

important

life

pathogens

disease.

example,

is

in

dead

young

children.

donations.

93

6.6

Xylem

and

transpiration

Plants LEARNING

is

At

the

end

should

be

of

this

able

topic

water

leaves.

you

large

to:

cell

•

define

require

the

terms

will

internal

a

water

as

state

it

that

pathway

travels

xylem

composed

damp.

explain

of

xylem

how

taken

through

by

a

is

a

xylem

the

vessels

discuss

the

tissue

is

structure

suited

roles

transpiration

have

in

vapour,

inside

the

there

and

at

water

vapour

to

of

The

their

the

gaseous

with

occurs

to

and

of

the

water

5.9

exchange

air.

at

The

any

allow

the

The

is

a

air

surfaces

that

for

cell

damp

carbon

air

inside

body

of

vapour

leaves

a

plant

from

have

their

a

very

photosynthesis.

walls

of

surface

dioxide

the

leaf

concentration

outside.

of

through

cells

the

leaf

of

of

all

tend

of

water

in

the

veins

the

by

leaf.

to

evaporation

then

plants.

molecules

loss

the

the

trans

to

explai n

piratio n

cons eque nce

surfac e

all

these

Each

cells

in

to

contact

diffuse

with

into

is

fully

gradient

Transpiration

mesophyll

cells,

saturated

the

between

is

the

followed

by

with

the

air

evaporation

the

diffusion

stomata.

dry,

is

way

sunny

from

trunks

of

to

‘stick

This

pull

the

the

large

to

pull

the

soil.

causes

of

a

are

the

water

in

in

to

called

on

the

move

walls.

the

the

cohesion.

water

from

The

xylem

in

of

water

the

the

under

faster

tension

can

than

be

between

xylem

pulling

transpiration

occurs

the

pulled

force

pull

cell

columns

water

result

a

a

water

in

roots

moves

loss

trees

to

the

As

creates

water

transmitted

down

days

together’,

evaporation

replace

transpiration

of

is

a

having

area

fo r

in

hair

through

cell

so

in

effect

stem

and

stream.

tension.

water

On

can

great

be

that

inwards.

tissue

and

water.

permeable

into

root

into

the

Water

cell

hair

moves

wall

cells.

and

From

by

the

here

osmosis

from

differentially

water

the

soil,

permeable

moves

across

Xylem

tissue

is

the

xylem.

photographs

in

Figure

6.6.1

show

the

pathway

taken

by

water

leave s. inside

6.6.1

absorb

fully

membrane

root

a

cells

the

gas The

exchan ge

stained

by

the

dyes

and

The

celery

stalks,

dissected

coloured

vessels.

94

so

leaf

water

Root

Figure

4.3

as

TIP

prepar ed

large

for

from

contact

spaces.

of

absorbed

that

in

stomata

of

hot,

Be

air

water

This

EXAM

Most

vessels

function

•

surface

Evaporation

Leaves

Water

•

water.

quantities

pull

plant

•

of

large

remember

surface

intercellular

the

lose

and air.

outline

volumes

plants

transpiration,

stream

transpiration

and

You

has

are

transpiration

•

large

OUTCOMES

out

which

from

strands

celery

in

are

the

petioles

of

leaves.

petioles.

the

photographs

of

the

celery

are

xylem

They

are

•

wide

•

no

columns

tubes,

cell

water

cellulose

•

no

•

thick

end

cell

therefore

walls

walls

Xylem

cells

Advantages

to

movement

use

Sun.

any

energy.

water.

This

water

the

are

that

that

provide

little

cells

from

of

the

tend

one

with

to

‘stick’

help

transport

water:

resistance

to

the

flow

another

lignin,

which

prevents

the

vessels

water.

Figure

6.6.3

Lignin

much

in

plant

the

is

laid

walls

vessels

in

down

of

Figure

as

a

raw

Xylem

spirals

and

an

in

to

fill

•

for

the

is

(×300)

a

through

passive

all

the

xylem

process

the

parts

does

driven

of

the

not

by

require

energy

plant

with

the

from

a

plant

the

supply

of

KEY

POINTS

for

Transpiration

of

to

to

dissolve

cells

cool

mineral

is

the

photosynthesis

so

they

plants

in

support

hot

the

plant

surfaces

ions

such

as

nitrate

ions

of

followed

weather

of •

in

needed:

vacuoles

evaporation

viewed

microscope

(×450).

evaporation

•

vessels

electron

transpiration

It

material

6.6.4

xylem

1 •

of

to

rings

provides

is

to

flow

molecules

made

are

other

water

Transpiration

tubes

features

(×100).

of

of

following

can

strengthened

vessels

than

the

water

hollow

tension

cells

wider

of

water

are

the

have

dead)

that

that

from

from

The

are

separating

walls

6.6.2

that

plenty

vessels

cell

collapsing

cells

that

contents,

(xylem

•

Figure

so

of

and

magnesium

water

of

water

at

mesophyll

by

the

the

cells

diffusion

vapour

through

ions

stomata. that

One

of

are

disadvantage

water.

do

transported

need

which

They

do

of

not

the

transpiration

transpiration

not

continually

may

in

need

to

always

to

grow

be

use

roots

is

that

energy

to

stream.

plants

to

reach

require

move

fresh

the

large

water,

sources

of

volumes

but

2

Evaporation

water,

The

transpiration

pathway

xylem

roots

and

the

following

transpiration

terms:

transpiration,

transpiration

Explain

why

4

transpiration

is

a

consequence

of

Describe

4

Explain

5

Outline

the

pathway

taken

by

water

as

it

to

Xylem

is

water

xylem

vessels

are

adapted

passes

to

the

advantages

and

their

disadvantages

of

from

the

leaves.

are

empty

through

a

plant.

walls

resistance

that

to

columns

cells

without

Their

provide

the

cell

flow

walls

little

of

are

function. strengthened

plants.

by

photosynthesis.

water. how

vessels

the

vessels

wide

end

3

stream

taken

pull

stream

of 2

move

QUESTIONS in

Define

the

to

available.

the

1

pull

water.

3

SUMMARY

drives

transpiration

they

transpiration

to

prevent

with

collapse

lignin

when

to

under

tension.

95

6.7

Investigating

transpiration

A LEARNING

potometer

how

At

the

end

should

•

be

outline

of

this

able

how

topic

less

you

to

to

much

than

some

to:

use

of

the

the

investigate

1

transpiration

explain

the

external

to

effects

factors

plants

measure

volume

water

of

is

take

up.

transpiration

water

used

for

The

taken

volume

indirectly

in

by

of

the

photosynthesis

water

by

roots.

and

lost

finding

This

to

is

out

is

keep

slightly

because

cells

turgid.

measure

rate

of

water

uptake

rates

Leafy

shoots

entering •

used

water

a T o

potometer

of

is

OUTCOMES

are

xylem

cut

under

vessels

water

and

and

blocking

kept

there

to

prevent

air

them.

of

on

rates

of

2

The

3

The

potometer

is

put

into

tap

reservoir

a

large

basin

of

water

and

submerged.

transpiration

•

describe

and

adaptations

explain

of

the

plants

the

The

stem

tight

5

The

be

of

6

7

fit.

should

The

8

of

The

may

A

potometer

the

rate

leafy

of

water

shoots.

page

101

is

potometer

for

can

uptake

uptake

1

like

this

by

is

left

has

0.01 g

if

over

short

a

placing

of

there

is

water

inside

angle

to

give

a

large

surface

for

This

bubble

the

of

is

a

the

Put

water.

so

tubing,

a

by

After

glass

the

reaches

the

air

different

a

making

while

tubing

inside

that

uptake

travelled

you

rubber

the

bubble

while,

water

be

reservoir

air

be

the

a

leaks.

from

an

may

that

can

inside

no

the

shoot

constant

bubble

period

over

of

a

will

bowl

tubing.

leafy

a

air

into

a

time

adjusts

rate.

suitable

for

each

investigate.

re-set

to

the

end

of

the

capillary

tube

by

tap.

environmental

conditions

on

the

rate

of

water

uptake

by:

•

placing

•

using

•

use

a

black

bag

over

the

leafy

shoot

to

find

out

the

effect

of

darkness

a

a

clear

bag

over

the

leafy

shoot

to

investigate

the

effect

of

one.

air

a

fan

or

hair

dryer

to

increase

the

wind

speed

shading

and

lamps

on

loss

to

a

provide

different

light

intensities.

both

in

factors

affecting

transpiration

balance

mass.

measure

results

to

transpiration

The

•

to

be

period

of

time.

–

vapour

to

are

Light

major

taken

•

Stomata

diffuses

factor

Humidity

The

–

in

for

than

in

of

in

darkness

leaves

determining

of

air

inside

the

water

transpiration

steep

close

out

The

humidity

gradient

96

an

tubing.

for

and

distance

time.

be

there

investigated

•

on

diagram

measure

and

put

measure

balance

at

placed

glass

Environmental

to

that

KNOW?

Potometers

are

so

closed.

removed

conditions

air

be

is

the

that

the

of

effect

still

they

opened

measuring

Figure

a

so

Measure

The

if

cut

and

conditions

opening

6.7.1

into

apparatus

the

set

water

is

then

should

potometer

taken

period

YOU

is

be

water

There

water

to

DID

It

water. absorbing

Figure

the

tubing.

to 4

conserve

on

glass

dry

how

leaves

vapour.

air.

the

In

open

fully

air

humid

in

stomata

much

is

surrounding

because

and

through

light.

their

As

transpiration

saturated

determines

conditions

concentration

water

a

water

vapour.

concentration

there

gradient

is

occurs.

with

the

most

width

for

is

less

water

is

less

•

Temperature

inside

the

vapour

•

Wind

–

than

speed

reducing

–

molecules

In

conditions

This

cooler

the

steepness

Warm

leaves.

is

are

still

air,

blown

the

the

warmer

air

rate

of

holds

evaporation

more

water

air.

water

concentration

of

increase

because

away

vapour

gradient.

from

concentration

the

remains

In

windy

leaf

gradient

near

the

leaves

conditions,

surface,

(Figure

so

water

increasing

the

6.7.2).

noitaripsnart

noitaripsnart

noitaripsnart

fo

fo

fo

Figure

6.7.3

Some

etaR

etaR

etaR

that

plants

roll

vapour

to

near

epidermis,

rate

25

50

75

100

10

15

20

25

0

8

of

have

keep

the

so

leaves

water

lower

reducing

the

transpiration.

16

–1

Humidity / %

Figure

6.7.2

The

Temperature / °C

effect

rates

Adaptations

There

of

are

many

transpiration

features,

rather

which

than

•

deep

•

extensive,

•

thick,

of

allow

it

that

increasing

plants

that

and/or

humidity,

temperature

and

wind

speed

on

in

is

to

obtain

places

in

short

obtain

and

where

supply.

sufficient

conserve

there

They

are

high

have

water

water

rates

special

and

retain

it

transpiration:

extend

to

roots

cuticles

to

live

water

them

in

shallow

waxy

of

velocity /km h

transpiration

plants

losing

roots,

of

Wind

great

that

over

the

depths

cover

stems

a

wide

and

area

leaves

to

reduce

the

water Figure

loss

through

the

upper

and

lower

6.7.4

Sea

epidermis

grape

root

with

•

thick

leaves

and/or

stems

to

store

water;

plants

like

this

are

has

system

thick

an

and

extensive

leaves

cuticles.

The

called leaves

are

arranged

shade

each

to

succulents.

KEY

SUMMARY

State

what

happens

to

water

taken

up

by

plants

that

is

List

the

with

precautions

potometer

Rates

to

that

measure

should

the

rate

be

of

taken

water

when

uptake

using

by

a

2

a

leafy

List

the

factors

that

influence

rates

of

a

Light

a

Describe

and

explain

the

adaptations

of

plants

that

water

is

in

short

Outline

the

abiotic

potometer.

intensity,

factors

of

humidity,

and

that

wind

speed

influence

transpiration.

Plants

have

adaptations

for

supply. water

b

and

measured

grow 3

where

uptake

are

transpiration. rates

4

water

temperature

shoot.

are 3

of

transpiration

not

transpired.

2

POINTS

QUESTIONS

1

1

other.

factors

that

make

these

absorption,

water

adaptations storage

and

reducing

the

necessary. rate

of

transpiration.

97

6.8

Phloem

Sources LEARNING

the

end

of

this

topic

be

able

plant

transport,

described

define

the

term

translocation

and

state

that

substances

transported

in

the

ions

travel

which •

as

a

the

organ

source

where

and

any

substances

destination

is

start

a

their

sink.

are

are

absorbed

in

xylem

all

sinks.

by

vessels

the

to

root

stems,

system,

leaves,

which

buds,

is

to

how

fruits,

of

water

in

sugars

are

xylem

sink transport

explain

source,

and

are

made

•

the

flowers

Simple

source

and

phloem

Uptake

from

movement

Water

to: mineral

•

sinks

you is

should

storage

OUTCOMES

In At

to

and

the

of

sucrose

in

in

the

leaves

by

phloem

photosynthesis.

structure

These

Bud

of

phloem

is

suited

to

are

its

converted

to

Leaf

function

sucrose,

Sunlight

energy

•

identify

in

storage

plants

and

compounds

animals

and

in

where

they

are

phloem

the

the

dioxide

rest

the

the

importance

in

to

plant.

of

and

other

sugars

of made

storage

the

transport

sucrose discuss

tissue

of

stored

Simple

•

transport

Carbon

In places

for

organisms.

Simple

by

products,

such

as

sugars photosynthesis

amino made

from

and

the

leaves

and

minerals

Sucrose

soil

moves

growing

root

growing

bud

down

or

up

are

the

other

source

organs

are

to

sinks.

to

This

called

Water

the

into

sucrose

Water

acids,

and

transport

is

translocation,

which

means

‘from

minerals

place taken

by

to

place’

up

(Figure

roots

6.8.1).

Substances

Figure

6.8.1

Transport

in

xylem

and

are

phloem

transported

phloem

directions:

flowers,

and

tubes.

by

parallel

These

have

many

prevent

end

Sucrose

an

veins In

this

cross-section

tissue

you

some

sieve

plates,

many

sieve

pores

of

can

‘head

to

roots,

from

upwards

storage

from

organs

to

leaves

new

to

stems

to

columns

to

reduce

the

into

the

leaf

living

cells

The

sieve

under

the

sieve

requiring

to

plates.

to

tubes

energy.

provide

concentration

causes

water

that

end

pressure

resistance

mitochondria

high

throughout

them.

form

bursting

process,

of

between

pores

moved

The

vessels

to

of

at

Cells

the

is

6.8.2

in

the

surrounding

in

by

for

the

cytoplasm

that

contents

source

sieve

perforated

thought

their

energy

in

phloem

some

are

(Figures

sucrose

diffuse

It

the

are

contain

walls

of

flow

plants

this

sieve

osmosis.

they

and

and

are

6.8.3).

leaves.

sieve

tubes

loading

tubes

This

This

of

in

the

builds

of

pressure’

that

forces

the

phloem

sap

out

of

the

leaf

up

veins

see

each

with

(× 130).

into

the

flow.

when

98

also

the

of

a phloem

is

many

sucrose.

6.8.2

leaves

and

xylem

walls

cells

active

have

Figure

from

buds

to

are

small

the

perforated

is

and

in

different

leaves.

Running

and

downwards

fruits

in

stem

The

and

highest

plants

are

on

to

rates

the

of

sinks.

This

translocation

producing

lots

of

mechanism

occur

sugar.

on

is

called

warm,

pressure

sunny

days,

Storage

When

stems

swell

in

growing

or

roots

with

nutrients

In

be

plants,

that

are

often

are

to

provide

once

Fat

fat

the

too

a

for

they

corms,

for

under

and

are

too

is

the

may

too

to

the

or

too

survive

and

a

starch,

for

with

harsh

and

to

leaves,

organs

protein

of

or

energy

a

and

Conditions

periods

are

all

Plants

before

store

the

food,

organs

food

in

germination

that

seeds

and,

established.

store.

large

good

store

growing

storage

during

energy

are

Structures

reproduction

become

around

Humans

or

supply

photosynthesis.

embryo

to

lipids

a

reproduction.

rhizomes

the

sucrose

storage

cold.

long-term

skin

These

provide

reproduction.

for

kidneys.

transport

vegetative

seedling

with

be

harsh

or

associated

bulbs

the

plants

storage.

organs

wet

asexual

energy

animals

for

which

vegetative

for

good,

Storage

have

enough

layer

heart

hot,

storage

germinated,

provides

in

food,

conditions

food

used

are

animals

modified

three.

produced

T ubers,

also

all

dry,

because

again.

are

stored

of

when

too

and

conditions

that

the

combination

may

plants

at

Mammals

organs,

storing

store

such

fat;

as

this

was Figure

probably

a

useful

adaptation

for

times

when

food

was

scarce.

This

6.8.3

Sieve

plates

clearly

rarely

the

case

now,

yet

we

still

store

fat

easily

and

have

an

are

visible

obesity

well

as

to

show

vitamins

for

and

it

(see

5.7).

minerals,

The

such

liver

as

also

vitamin

stores

B

some

and

iron

in

th is

epidemic longitudinal

of

also

is

–

fat

as

phloem

sectio n

sieve

of

tubes.

both

12

needed

Fat

it

for

stores

for

the

are

put

buoyancy

vitamins,

such

Define

to

and

as

SUMMARY

1

production

good

as

a

of

red

use;

for

thermal

vitamin

blood

cells.

example,

insulator.

It

marine

also

mammals

stores

use

fat-soluble

A.

QUESTIONS

the

terms

translocation,

source

and

sink

Figure

6.8.4

A

seed

in

an

early

germination.

2

Describe

briefly

how

sucrose

is

transported

in

the

provide

Make

4

Explain

fat

KEY

1

a

table

a

why

stored

by

A

source

is

a

Plants

the

the

the

have

and

storage

for

lipid

is

to

growth.

phloem.

organs

and

b

the

roles

of

in

and

a

the

where

sink

is

its

phloem

in

of

sucrose

and

other

organic

is

a

substance

begins

its

movement

destination.

by

pressure

flow

as

the

result

of

leaves.

animals

energy

movement

store

and

carbohydrate,

materials,

often

lipids

during

and

times

proteins

when

to

food

Figure

6.8.5

Hunter

Animals

thermal

store

gatherers

Kalahari

scarce.

often

5

energy

and

phloem.

organ

processes

provide

is

is

in

plant;

Movement

active

4

plants

xylem

starch

mammals.

Translocation

through

3

compare

of

POINTS

compounds

2

to

stage

embryo

phloem. respiring

3

The

fat

as

insulation

a

long-term

and

energy

buoyancy.

store

and

to

provide

to

where

be

store

plenty

energy

scarce.

fat

in

The

times

provides

in

from

food

times

ability

of

them

of

the

may

with

scarcity.

99

Unit

SECTION

1

6

1:

Practice

Multiple-choice

Plants

absorb

to

atmosphere.

the

does

A

water

pass

palisade

→

water

from

soil

mesophyll

root

hair

the

to

cells

soil

and

which

lose

it

6

When

blood

root

hair

cells

1

fibrinogen

→

xylem

root

2

prothrombin

cells

mesophyll

2

3

spongy

→

→

mesophyll

xylem

mesophyll

cells

3

platelets

which

process?

lost

from

xylem

cells

leaves

A

photosynthesis

B

respiration

C

translocation

D

transpiration

A

to

fibrin

is

converted

to

thrombin

release

calcium

substances

that

interact

ions

→

vessels

blood

cells

are

trapped

in

a

mesh

of

fibres

→

root

hair

blood

the

correct

sequence

of

these

stages

clotting?

to

the

atmosphere

are

dissolved

in

1

→

2

→

3

→

4

B

2

→

1

→

4

→

3

C

3

→

2

→

1

→

4

D

4

→

1

→

2

→

3

by

for

substances

A cells

human

Questions

7

and

1

Cytoplasm

2

Nucleus

3

Cytoplasm

plasma?

carbon

is

→

vessels

is

blood

converted

cells

Water

Which

is

vessels

hair

→

occur:

cells

in

D

following

vessels

Which C

the

atmosphere?

4 xylem

clots

structures

with

B

questions

questions

Through

from

exam

is

8.

is

full

of

haemoglobin.

lobed.

has

many

small,

enzyme-filled

vacuoles.

dioxide,

haemoglobin

and

4

Shape

is

5

Cell

6

Nucleus

a

biconcave

disc.

glycogen

B

carbon

dioxide,

C

glucose,

D

oxygen,

protein

hormones

and

and

and

no

nucleus.

occupies

most

of

the

cell.

urea 7

urea

has

starch

Which

of

these

features

describes

red

blood

features

describes

phagocytic

sucrose cells?

4

Which

is

the

circulation?

whole

A

body,

from

description

each

blood

the

before

correct

In

complete

of

the

circuit

of

human

alimentary

returning

through

the

1,

2

and

3

B

1,

4

and

5

C

2,

3

and

6

D

3,

4

and

5

passes

to

canal

the

to

the

liver

heart

8 B

A

the

pulmonary

circuit

and

Which

white systemic

C

through

before

D

before

5

Which

is

the

four

to

arteries,

effect

chambers

the

returning

an

of

the

the

and

heart

smoking

on

in

A

1

and

5

B

2

and

6

capillaries

C

2

and

3

D

3

and

5

veins

the

gas Which

carbohydrate

system? tissue?

100

A

bladder

B

chronic

C

heart

D

high

cells?

heart

lungs

arterioles

to

of

9

exchange

these

blood

circuit

going

through

of

the

cancer A

Fructose

B

Glucose

C

Maltose

D

Sucrose

bronchitis

disease

blood

pressure

is

transported

in

phloem

SECTION

10

A

2:

student

Figure

1

Short

used

to

answer

the

questions

potometer

investigate

the

shown

effect

of

in

d

Use

i conditions

on

the

rate

of

water

the

results

to:

different Describe

the

movement

by

ii

Leafy

effect

of

humidity

and

air

uptake.

the

on

leafy

Explain

the

rate

of

water

uptake

shoot.

the

effect

of

increasing

air

shoot

speed

Reservoir

and

decreasing

humidity

in

the

investigation.

Air

e

bubble

The

lower

shoot

jelly,

in

(6)

surfaces

Figure

which

is

1

of

all

were

the

leaves

coated

impermeable

to

in

of

the

petroleum

water .

The

Reservoir

shoot

was

then

exposed

to

dry,

moving

air .

Water

Ruler

i

Figure

Predict

1

ii The

the

result

that

would

be

obtained.

student

set

up

the

potometer

in

a

Give

an

(2)

explanation

for

your

brightly prediction.

lit

laboratory

at

room

temperature

and

f three

sets

of

conditions,

A,

B

and

C,

as

The

still,

humid

B

moving,

air

humid

moving,

dry

this

repeated

time

balance

Explain

air

in C

student

the

investigation,

follows: but

A

(3)

provided

to

the

mass

as

placed

record

the

any

advantage

well

as

the

potometer

changes

of

in

measuring

uptake

of

each

case,

the

before

student

waited

for

taking

any

readings.

T able

results

are

shown

in

T able

Figure

2

shows

of

a

the

ginger

Distance

in

travelled

different

by

the

air

rhizome

growing

at

the

season.

1.

New

minutes

marks

The

1

Time/

25

10

beginning student’s

(3)

air.

11 minutes

a

changes

water .

Total

In

on

mass.

shoot

bubble

conditions/mm

Rhizome

A

B

C

Figure

2

3

6

8

4

4

12

16

6

7

17

30

10

9

21

57

a

Describe

of

b

2

how

carbohydrate

Explain

the

11

25

could

are

in

find

stored

advantages

carbohydrate 12

you

of

out

in

the

what

types

rhizome. (7)

storing

structures

such

as

rhizomes.

86

(3)

a

Describe

student

three

precautions

should

take

when

that

c

the

setting

up

the

potometer.

b

Explain

why

minutes

set

of

(3)

the

before

student

taking

waited

readings

for

for

Explain

new

why

shoots

materials,

the

are

rather

Draw

graph

of

the

than

the

for

a

tips

the

of

the

transport

source.

Total

10

conditions.

a

at

sink

of

(5)

15

marks

each

(2)

Further c

cells

a

results

in

the

table.

practice

questions

(6) and

on

examples

the

can

be

found

accompanying

CD.

101

7

Excretion

7.1

the

end

should

be

of

this

able

define

•

distinguish

•

Metabolism

is

bodies.

of

the

topic

of

you

no

Some

chemical

use

and

may

chemical

and

physical

even

be

processes

changes

toxic

if

produce

that

occur

allowed

to

substances

in

that

are

accumulate.

to:

term

the

Excretion

excretion

between

ways

metabolic

from

excretion

Waste

in

humans

substances

in

produced

by

humans

are:

wastes

plants

and

•

carbon

•

urea

•

bile

dioxide

are

from

the

water

in

from

how

animals

and

substances

catalase

cells

broken

plants

by

(see

the

excess

amino

acids

bilirubin

dead

and

aerobic

dioxide

is

biliverdin,

is

blood

from

the

breakdown

of

cells

respiration.

the

it

red

waste

product

carried

in

the

of

aerobic

blood

to

respiration.

the

lungs

Produced

where

If

carbon

dioxide

accumulated

in

the

body

it

it

would

is

be

toxic

peroxide, as

by

of

one

hydrogen

produced

in

mitochondria,

excreted.

immediately

breakdown

pigments,

Carbon

substance,

respiration

animals.

LINK

seen

aerobic

excreted

•

have

from

which

haemoglobin

is

the

the

egestion

state

We

all

OUTCOMES

•

and

movement

Excretion

LEARNING

At

and

and

causes

acidosis

–

a

condition

that

leads

to

cell

damage.

is

down

to

it

Amino

in

harmless

that

enzyme

acids

proteins,

are

(Figure

5.4).

can

be

excess

used

pH

are

they

our

This

in

of

less

for

water

is

the

its

from

stored

requirements

process

cytoplasm

by

be

respiration

Ammonia

converted

absorbed

cannot

to

7.1.1).

storage.

the

that

but

forms

or

toxic

in

making

liver

into

the

as

are

less

which

is

used

Any

down

and

into

be

acids.

in

to

the

carbohydrates

active.

less

make

amino

because

It

is

that

or

it

acids

liver

compounds

concentrations

enzymes

urea,

can

broken

ammonia

converted

low

gut

amino

fat

for

increases

immediately

harmful

and

requires

excretion.

Cells Protein Gut

Some

acids

into

Skin

excretes

Digestion

urea

amino

are

built

protein

make

new

to

Excess

cells

taken and

amino

to

the

acids

liver

are

and

salts changed

into

Urea

urea

Lungs Absorption excrete

carbon

dioxide

Liver

Amino

acids

Liver Figure

processes

7.1.1

This

the

materials

makes

shows

what

happens

to

the

amino

acids

that

are

absorbed

from

toxic small

intestine.

and

them

The

liver

also

breaks

down

old

red

blood

cells

to

release

harmless

haemoglobin.

Kidneys

excrete

and

iron

is

part

of

102

7.1.2

The

excretory

recycled

to

make

of

haemoglobin

new

are

haemoglobin.

broken

The

rest

down

of

the

and

the

haem

urea

haemoglobin

molecules

is

converted

into

bile

pigments,

salts

which

Figure

Molecules

organs

are

excreted

accumulate

in

the

in

urine

skin

and

and

faeces.

eyes

giving

If

not

them

excreted,

a

yellow

bile

pigments

colour.

Additionally,

the

liver

breaks

down

hormones

into

inactive

substances LINK

that

are

removed

from

the

body.

See The

body

also

has

more

than

enough

of

some

substances.

Water

3.4

cells example,

is

absorbed

into

the

blood

from

food

and

drink.

It

is

swell

as

a

waste

product

of

aerobic

respiration.

If

water

builds

up

body ,

many

If

that

The

•

ions

these

so

cells

(from

water

organs

Lungs

–

excess

leaves

–

and

•

Liver

–

•

Skin

filter

in

the

salts),

by

urea,

of

to

the

cells

is

alveoli

produce

with

can

in

have

and

less

the

if

the

there

is

too

much

water

body.

too

chloride.

concentrated

humans

from

why

even

efficiently .

are:

blood

by

5.9).

urine,

dissolved

too

function

lost

(see

also

sodium

become

7.1.2)

which

the

body

fluids

(Figure

dioxide,

walls

and

The

potassium,

tissue

osmosis

blood

(see

burst!

especially

and

excretion

requirements

salts

even

blood

cells

the

produces

–

and

carbon

across

of

urea

the

involved

excrete

Kidneys

swell

mineral

accumulate,

diffusion

•

could

yourself

possibly

in in

the

remind

and

also burst

produced

to

for

which

waste

is

water

substances

in

such

as

7.2).

bile

sodium

pigments

and

and

chloride

spent

ions

hormones.

are

excreted

when

we

sweat.

Figure

7.1.3

objects

in

The

oxalate

crystals

this

Agave

sharp

leaf

needle-like

are

calcium

Egestion

Egestion

but

not

such

is

the

removal

digested

as

fruit

egested.

egested

and

and

Bile

in

vegetables,

they

faeces

absorbed.

pigments,

since

the

is

some

have

been

Fibre

the

of

of

anything

or

roughage

main

which

in

excreted

the

has

from

component

are

produced

that

liver

of

in

by

been

plant

our

the

ingested,

material,

diet

that

faeces,

our

herbivores.

the

stoma

that

Notice

at

the

top

are

not

KEY

waste

is

the

the

leaves.

Other

waste

that

from

product

respiration.

for

their

excretory

compounds

oxalate,

fall

of

day

are

plants.

to

used

of

photosynthesis;

Some

respiration;

compounds

make

the

the

being

oxalate

oxygen

rest

cannot

substances,

before

Calcium

of

is

diffuses

be

such

excreted

crystals

carbon

are

lost

as

in

dioxide

used

out

so

Metabolism

very

and

and

sharp

the

the

damage

plants

Plants

of

the

how

mouths

they

and

(Figure

that

of

herbivores;

tannins

also

deter

as

do

this

is

not

known

for

terms

2

Distinguish

3

a

and

b

Make

a

table

animals

and

Explain

why

to

the

excretion

show

ways

wastes

the

in

waste

must

be

products

is

Distinguish

between

excretion

egestion.

The

main

Explain

why

dioxide

at

plants

night.

excrete

products

each

is

of

plants

excreted

animals

oxygen

of

substances

in

excess,

and

ions.

removal

material

metabolic

humans

The

are

of

through

urea

wastes

and

dioxide.

and

from

the

5

body .

kidneys,

are

Plants

and

gas

and

in

during

the

lungs,

excretory

excrete

carbon

liver

and

organs.

oxygen

dioxide

exchange;

by

organic

such

as

calcium

plants. oxalate

5

the

anus.

skin

excreted.

in

toxic

the

compounds

4

is

body

excretion

and

which

in

certain.

4

between

the

water

Egestion

in

metabolism

occur

7.1.3)

carbon

the

the

herbivores,

3

Define

all

substances

such

QUESTIONS

1

and

physical

from

waste

the

SUMMARY

cuticle

leaf.

excretion

metabolism,

use

calcium

bark

that

undigested

although

the

is

and

body;

removal

their

easily.

tannins

leaves

by

of

is

2

and

deterring

plants

waste

product

during

of

at

waxy

POINTS

changes

Oxygen

thick

metabolism.

chemical

in

the

good

is

1

Excretion

are

day

and

carbon

leaves

for

are

and

stored

bark)

(e.g.

and

in

used

protection.

103

7.2

The

human

urinary

system

One LEARNING

the

At

the

should

end

be

of

the

of

this

able

topic

urinary

describe

excretory

the

system

(Figure

organs

in

humans

is

the

kidney.

It

is

part

of

7.2.1).

you

to:

Renal

•

main

OUTCOMES

human

vein

takes ‘cleaned’

urinary

Renal blood

away

from

the

ar ter y

brings

waste

to

kidneys the

kidneys

in

the

blood

system

Kidneys

•

describe

of

•

the

internal

structure

and

the

structure

of

remove

other

from

kidney

describe

kidney

the

the

urea

chemicals

blood

a

nephron.

Ureters

to

the

carr y

Bladder

Ring Urethra

carries

Figure

The

Figure

7.2.2

A

kidney

ureter

with

part

of

the

of

the

7.2.1

of

stores

urine

muscle

until

keeps

you

the

bladder

urinate

body

The

functions

down

urine closed

out

urine

bladder

of

human

the

•

excretion

•

osmoregulation

urinary

kidney

system

are:

attached

–

maintenance

of

constant

water

content

of

the

body

•

maintenance

potassium,

•

control

The

The

the

7.2.3

A

to

kidney

show

medulla,

cut

the

open

vertically

cortex,

pelvis

and

or

each

kidney

function

pH

and

of

the

in

Figures

internal

kidney

of

ions,

e.g.

sodium

and

blood.

structure

tubules,

of

concentration

blood

are

7.2.2

is

the

and

structure

thousands

which

nephrons

of

you

to

can

filter

of

of

7.2.3

the

tiny

only

the

kidneys

and

Figure

7.2.4

show

kidney.

tubes

see

blood,

called

under

a

nephrons,

microscope.

remove

waste

The

chemicals,

ureter

reabsorb

useful

reabsorbed.

the

104

the

photographs

external

constant

the

internal

Inside

Figure

of

of

in

body

in

substances

The

waste

urine.

and

allow

chemicals

and

water

excess

to

be

excreted

water

are

or

removed

from

Medulla

Cortex

KEY

POINTS

Medulla Pelvis

1

Renal

The

urinary

composed brings

to

the

ureters,

2

Each

vein

and

Figure

7.2.4

A

tubule

vertical

Collecting

section

of

the

duct

from

3

Kidneys

kidney

is

Cortex

on

the

with

a

detailed

view

of

a

renal

flows

artery

arterioles

a

in

a

which

the

is

renal

supplies

a

artery

many

blood

(Figure

cup-like

glomerulus

to

Urine,

which

excretory

out

to

a

times

a

7.2.5)

structure.

form

into

kidney.

to

form

closely

that

inside

is

glomerular

the

arterioles.

packed

fits

Blood

Inside

group

kidney,

Each

of

filtered

as

it

fl ows

Blood

the

stored

these

capillaries

Bowman’s

filtrate.

of

the

in

in

around

rest

the

the

renal

another,

of

the

vein

nephron

reabsorb

At

the

is

many

to

end

of

a

of

goes

the

from

kidney.

thinner

arteriole

nephron.

Blood

and

from

then

into

leave

coiled

the

the

Water

these

capillaries

to

wastes

solvent

yellow

be

the

may

Urine

stored

dissolved

for

these

pigment

in

in

microscopic

in

filtrate

medulla

be

tube.

the

Cells

filtrate

drains

and

reabsorbed

collects

the

in

the

bladder.

water.

wastes,

in

water,

urine

Water

such

is

Make

into

lining

back

a

the

into

it

nephron

the

–

as

made

bringing

to

bladder

be

until

QUESTIONS

a

diagram

empties

collecting

into

the

with

system

of

the

as

urine

pelvis

flows

and

the

flows

Urine

always

urea

in

is

and

the

a

has

solution

to

be

excess

body

of

the

of

each

Make

a

diagram

to

show

the

of structure

of

a

kidney

the

into

you

would

see

with

the

the

bile

as

eye.

Label

the

main

regions

of

the

Make

large,

kidney.

the

salts.

The

3

a

diagram

pigments.

of

a

will

need

question

1

labelled

nephron

associated

You

Glomerulus

Bowman’s

functions

excretory

present

mineral

from

annotate

duct,

pelvis

through

then

and

part.

blood.

its

Arteriole

ureters,

the

flows

naked ureter

in

kidneys,

kidney.

substances

nephron,

through

ducts.

the

capillaries

that collecting

of

the

internal the

solution

through

flows

2 which

a

called

urinary

Each

is

waste

capsule,

1 into

reabsorbed.

urination.

SUMMARY glomerulus

are

nephron

branches

glomerulus

blood

useful

three

along

Blood

and

left

passes

of

many

where

filtered

of

Structure

outer

a

pelvis.

contain

substances

4 nephrons

an

urethra.

kidney

nephrons

kidney

has

surrounding

medulla

Ureter

One

and

blood

away

the

is

kidneys,

bladder

kidney

cortex

takes

of

blood

kidney

Renal

system

artery

in

blood

this

to

and

vessels.

answer

7.3.

capsule

4

a

Suggest

the

Distal

convoluted

how

renal

blood

in

blood

vein

the

in

differs

renal

from

artery.

tubule

b Branch

Suggest

must renal

why

blood

of

flow

continuously

vein Loop

through

the

kidneys.

Proximal Capillaries

convoluted

tubule Collecting

duct

Filtration

Urine

Figure

7.2.5

A

nephron

105

7.3

Kidney

Pressure LEARNING

the

end

of

this

topic

kidneys

•

be

define

able

the

filtration,

and

terms

pressure

selective

reabsorption

high.

the

pressure

inside

Ions,

the

water

kidney

functions

net

with

nephron

in

describe

diuretic

of

role

of

hormone

how

is

in

used

kidney

tiny

of

holes

Small

the

blood

7.2.5

pressure

that

the

in

the

blood

wider

molecules

the

in

than

to

are

capillaries.

it.

Blood

the

one

increase

so

forced

The

cells

out

lining

and

leaving

that

of

of

large

it.

blood

the

the

This

is

causes

filtered.

blood

plasma

capillaries

molecules,

like

big

to

pass

through

the

capillary

lining

and

like

blood

so

molecules,

like

urea,

glucose,

amino

acids,

stay

ions

The

(ADH)

renal

the

are

filtered

into

Bowman’s

capsule

to

form

filtrate

in

and

(Figure

blood

that

entering

flows

7.3.1).

from

the

glomerulus

has

less

plasma

than

the

it.

dialysis

treatment

of

FOCUS

a

in

drawing

(see

of

question

with

urea

waste

renal

and

substances

artery

the

3

in

7.2) Urine

you

is

failure.

Annotate

as

renal

vessel

anti-

other

nephron

is

glomerulus

small

too

Blood

STUDY

so

Figure

urine

the

outline

the

walls

are

blood.

blood •

heart,

from

the

water , •

the

see

of

the formation

to

can

glomerulus

and

the

proteins, the

close

Y ou

entering

through

osmoregulation

describe

is

to:

a •

are

you artery

should

filtration

OUTCOMES

The At

functions

read

this

section. with

most

of

urea

removed

the

flows

collecting

Blood

down

duct

to

ureter

Water

maybe

reabsorbed

Pressure

filtration from

urine

Blood Plasma

protein

pressure

STUDY

FOCUS Blood

in

It

is

important

concentration

that

of

in

capillary

glomerulus

the

blood

and

Capillary

tissue

fluid

When

is

there

kept

is

wall

constant.

plenty

of

water Selective

in

the

does

the

body,

not

the

secrete

collecting

impermeable,

reabsorbed

is

produced.

ADH,

ducts

no

and

reabsorption

hypothalamus

are

water

dilute

The

is

Filtrate

in

Bowman’s

capsule

urine

control

of Capillary

water

in

the

body

hypothalamus,

by

ADH

the

convoluted

and

All

glucose,

some

water,

Water All

the

kidney

is

an

example

of

these

–

maintaining

body

constant

(see

conditions

in

some

the

blood

the

into

into

capsule

Ions

8.8). Figure

106

tubule

Urea Bowman’s

near

filtered

ions

pass

Glucose from

homeostasis

are

7.3.1

Filtration

and

reabsorption

in

a

nephron

the

blood

back

Selective

reabsorption LINK

The

body

needs

glucose,

amino

acids,

some

ions

and

much

of Try

the

water.

The

cells

lining

the

first

part

of

the

nephron

to

convoluted

tubule)

reabsorb

these

from

the

filtrate.

question

11

on

page

113

(proximal

Glucose,

ions

find

out

more

about

kidney

and dialysis.

amino

by

acids

are

osmosis.

ions.

be

As

The

the

waste

filtrate

filtrate

reabsorbed

collecting

reabsorbed

if

ducts

the

is

chemicals,

kidney

body

to

is

water.

urine.

urine

is

a

in

water

blood,

dilute

water

with

The

a

the

lower

the

passes

solution

of

urea,

excess

water

enters

may

the

concentration

of

vein.

out

collecting

and

that

conserving

water

reabsorbed

more

fluid

renal

is

urea

nephron,

with

in

and

fluids,

the

water.

kidney

much

with

transport;

mostly

low

The

the

how

supplied

The

is

active

through

hormone

controls

well

now

on

body

leaves

Anti-diuretic

The

is

fl ows

by

in

the

ducts

salts

water

urine.

are

and

If

the

impermeable

Figure

7.3.2

Kidney

visits

other

a

compounds.

it

is

hot,

If

you

you

have

are

dehydrating

in

drinking

been

the

brain

anything,

sweating

(see

concentration

the

pituitary

8.4)

of

the

gland

hormone

(ADH).

cells

the

lining

permeable

blood

to

a

vessels

the

urine

to

the

of

blood

to

lot

and vessels

the

the

epithelial

become

Blood

Blood

in

out

surrounding

have

water

by

a

high

diffuses

osmosis.

from

Dialysis

This

fluid

Dialysis

out

forms

that

concentrated

would

urine

otherwise

conserving

have

been

Figure

out.

7.3.3

As

blood

and

flows

through

concentrations

in

people

accident

die

in

a

most

and

of

have

or

very

dialysis.

the

of

dialysis

glucose

the

water

kidney

have

short

Their

an

content

failure,

infection.

time.

blood

These

flows

excretory

SUMMARY

of

If

people

a

without

plasma

because

nothing

through

waste

the

perhaps

can

is

be

done

it

using

machine

unbalancing

have

about

treated

dialysis

(Figure

they

the

they

1

7.3.3).

2

Annotate

your

functions

of

diagram

the

of

different

a

nephron

(from

7.2)

with

the

diffuses

stabilised.

and

Make

a

flow

chart

diagram

to

plasma

Bowman’s

Useful

how

the

pituitary

control

gland,

of

the

blood,

kidneys

concentration

and

of

ADH

are

of

some

the

the

between

pressure

and

involved

in

Explain

the

role

5

Explain

how

of

ADH

in

the

3

ADH

selective

dialysis

body.

saves

the

It

lives

of

the

is

are

the

filtrate

capillaries

nephron.

secreted

people

is

too

stimulates

by

the

when

the

water

concentrated.

the

from

uptake

urine

in

with

collecting kidney

as

and

reabsorption.

of kidney

such

salts

the

blood

4

filtrate

hypothalamus,

urine.

filtration

the

capsule.

water

blood

ions,

leave

form

from

hypothalamus Distinguish

to

materials

reabsorbed

show

urea,

water

in

the

occurs

through

blood

most

parts.

flows

glomerulus;

glucose

glucose

filtration

blood

the

removes

QUESTIONS

Pressure

as

kidney

that

salt,

will

along

3

urea

are

POINTS

into 2

ions

been

glucose,

1

machine

and

dialysis KEY

Some

fluid

in

water

passed

out

Kidney

times

anti-diuretic

ducts

medulla

so

three

week.

stimulates

makes

The

salt,

the

It

release

collecting

in

into

responds

ADH

involves

clinic

hypothalamus

blood.

water.

concentration

the

a

because

Blood

not

dialysis

to

ducts.

failure.

107

7.4

Movement

Movement LEARNING

Movement At

the

end

of

this

topic

be

able

define

and

animals

its

is

an

action

position

or

by

an

organism

or

part

of

an

organism

that

place.

to:

Plants •

plants

you changes

should

in

OUTCOMES

movement

are

fixed

in

one

position

and

have

spreading

bodies

that

and absorb

light,

carbon

dioxide,

water

and

mineral

ions.

Some

plant

locomotion movement

•

distinguish

flytrap

locomotion

in

animals

movements

are

in

grains

outline

for

the

roles

animals

and

of

movement

plants

these

to

and

competition

methods

describe

how

human

its

plant

the

structure

expose

and

reproduce

the

Venus

they

one

plant

to

another.

Their

make

seeds

(see

plant

to

colonise

new

areas

and

are

reduce

9.6).

are

due

to

growth

and

are

slow

(see

8.2

for

They

their

relate

leaves

to

skeleton

is

to

their

as

nutrition.

much

light

Shoots

as

grow

possible

so

towards

that

they

light

efficiently.

Roots

grow

downwards

towards

can

sources

related water.

functions.

animals

which

is

about

by

7.4.1

The

of

cotyledons

this

peanut

(seed

have

into

for

so

the

the

shoot

light

to

•

hide

•

migrate

•

find

mates

•

find

nesting

and

in

one

place.

They

Movement

move

in

their

animals

is

whole

body,

brought

contraction.

necessary

escape

to

animals

move

gain

to

from

avoid

coral

to:

harsh

sites

are

and

fixed

polys,

food

predators

make

and

sea

and

conditions

or

in

search

of

food

nests

only

move

anemones

defend

part

and

of

their

barnacles.

bodies,

Parts

of

for

their

body

themselves.

leaves)

moved

can

human

skeleton

grow

absorb

light

Locomotion

is

crucially

important

to

humans.

We

are

bipedal

(we

photosynthesis.

front

on

The

two

limbs

which

or

be

eaten.

and

running

for

Both

cheetah

their

are

lives.

us

functions

T ry

gazelle

legs).

free

allow

STUDY

Eat

fixed

locomotion.

food

example

walk

7.4.2

is

not

as

muscle

find

The apart

are

known

•

Some

108

from

parent

movements

Locomotion

Figure

mimosa

of

Most

Figure

of

plants

reproduction

of

to

move

the

photosynthesise

the

leaves

When

of

to

•

that

from

examples). nutrition

the

8.1).

and Most

relate

fast:

(see

plants dispersed

•

quite

examples

and pollen

growth

occurs

between

with

manipulate

grasp

the

objects.

objects

skeleton

four-legged

and

are

We

make

shown

have

and

in

animals,

we

opposable

use

T able

have

our

thumbs,

tools.

7.4.1.

FOCUS

you

names

to

of

answering

help

to

Compared

to

of

question

locate

the

the

bones

15

which

important

and

identify

you

will

parts

the

of

find

the

on

the

CD.

skeleton,

positions

of

the

This

learn

joints

will

the

(see

7.5).

T able

7.4.1

Functions

of

the

skeleton

KEY

Function

Comments

Locomotion

•

1 Bones

by

•

are

a

firm

structure

for

muscle

POINTS

Movement

is

organism,

or

skeleton

has

systems

of

levers

to

move

an

organism,

causing

body

from

place

to

place,

or

move

parts

the

body

relative

to

one

•

The

cranium

•

The

ribcage

protects

the

brain,

the

eyes

and

of

position

the

lungs

and

vertebral

column

protects

the

whole

The

types

spinal

plants

pelvis

protects

the

•

The

e.g.

bones

systems

•

The

•

The

provide

of

nervous,

uterus,

internal

the

body,

endocrine

backbone

the

ovaries

a

urinary

and

framework

such

and

provides

and

as

of

to

jawbones

The

ribcage

volume

of

red

for

the

all

the

digestive,

muscular

support

3

other

excretory,

and

cells

of

Red

bone

and

at

that

support

is

moved

muscles

the

the

up

to

thorax

marrow

the

ends

divide

for

the

functions

are:

locomotion,

limbs

and

Long

and

down

increase

(see

and

by

the

humerus

fore

is

of

bones,

support

decrease

skeleton

protection,

red

and

the

blood

cells.

in

of

the

by

long

mitosis

those

that

are

the

interior

of

have

the

short

and

produce

stem

red

removed

from

the

of

the

upper

arm

(Figure

QUESTIONS

cells,

blood

cells

Define

the

terms

movement

to

locomotion

circulation.

Write

a

7.4.3).

3

a

food

chain

organisms

Figure

bone

for

movement.

bones

limb

long

the

adapted

5.10).

bones

to

e.g.

are

the

three

The

the

teeth.

2

human

of

breathing

production

and replace

The

reproduction.

The

support,

systems.

1 blood

of

bladder.

SUMMARY •

are

forms

head.

intercostal

Production

animals

their

humerus,

•

movement

genital

4

Breathing

of

organism.

and

nutrition organs,

place.

cord.

related The

or

movement

heart.

in The

is

ears.

2 protects

a

another. the

Support

by

of

of Locomotion

•

part

the change

•

action

an tendons.

The

whole

Protection

an

attachment

for

the

visible

in

7.4.2.

Make

a

table

movement

to

in

compare

plants

and

animals.

Cartilage A

Rounded

blade

to

head

form

fits

a

into

ball

the

and

b

shoulder

socket

joint,

Explain

your

the

table

differences

from

part

in

a,

by

A allowing

movement

in

three

planes.

referring B

The

ends

of

the

humerus

are

made

bone,

which

is

light

and

the

forms

of

of

B spongy

to

nutrition

and

reproduction

in

and

animals.

strong

D and

withstands

stresses

in

all

directions.

plants

E C

Growth

D

Red

of

the

bone

occurs

here.

4 bone

marrow

in

the

ends

of

a

List

the

functions

of

the

the

F

human bone

produces

E

Yellow

F

The

the

bone

long

shaft

chances

red

blood

marrow

is

of

a

is

a

hollow,

break

cells.

store

G

of

which

fat.

b

State

the

body

that

the

The

occurring

outer

part

of

compact

Rounded

the

shaft

is

made

of

to

of

the

functions

in

listed.

J

ends

form

a

hinge

joint

Explain

how

radius

and

triceps

the

biceps

surface

as

this

other

of

is

the

blood

H

ulna.

and

muscles

shaft,

attached

to

the

not

the

formation,

scapula.

The

humerus

bone

in

showing

breathing,

protection

and

Cartilage

Explain

how

adapted 7.4.3

human

support.

6

Figure

the

involved

locomotion,

attach

but

is

with

C

The

the

bone.

skeleton

the

of

involved

across

5

J

are

bone.

strong,

H

bones

reduces

each

G

skeleton.

how

it

is

adapted

for

its

for

the

its

humerus

is

functions.

functions

109

7.5

Joints,

and

muscles

movement

Joints LEARNING

OUTCOMES

Locomotion At

the

end

of

this

topic

skeletal should

be

able

name

the

the

skeleton,

joints

between

the

bones

and

the

muscles.

to:

The •

involves

you

types

of

joint

in

place

where

two

bones

meet

is

a

joint.

There

are

two

types

of

the joint:

skeleton

• •

describe

movement

at

a

fixed

of •

describe

the

structure

of

•

describe

human

define

where

there

is

no

movement,

e.g.

between

the

bones

cranium

a

moveable

(or

synovial)

joint

where

there

is

movement.

joint

the

structure

of

T wo

the

types

of

moveable

joint

are

(Figure

7.5.2):

forearm •

•

the

a

• moveable

joint

joints

the

term

antagonistic

a

hinge

elbow

joint

and

in

the

which

movement

occurs

in

one

plane,

e.g.

at

the

knee

muscles •

•

explain

moves

how

the

a

pair

of

muscles

a

ball

e.g.

and

at

socket

the

joint

shoulder

where

and

the

movement

occurs

in

all

three

planes,

hip.

forearm.

Ligament-holds

Humerus

the

bones Synovial

fluid

together

Cartilage

Synovial

membrane-

produces

synovial

Ligament

fluid

Radius

Figure

7.5.1

You

can

see

the

cartilage

Plane at

the

end

of

the

bones

of

movement

of

Femur these

pig’s

Synovial

Pelvis

trotters.

Ulna membrane

Capsule

STUDY

You

a

can

pig’s

and

learn

a

trotter.

then

that

Figure

FOCUS

are

lot

separate

bones

to

across

the

the

see

the

to

the

the

skin

tendons

the

tendons

hinge

the

bones;

inelastic

collagen

and

joints

ligaments

and

open

pull

muscle

joints

cartilage

the

oily

to

and

find

the

lubricant.

and

a

ball

and

socket

joint

(hip)

on

up

of

the

inserts

to

fibres

each

bones

that

run

muscle.

tendons

moves;

by

deep

When

which

the

tendons.

is

bones

muscles

move

origin

into

These

the

the

to

The

full

form

contract

bone.

fixed

are

tough,

the

and

end

of

origin

shorten

where

the

end.

Cut

are

attach

also

bones

made

of

together

collagen

and

and

support

are

tough,

the

joints.

but

they

Most

have

of

some

the tissue

which

means

that

they

can

stretch

a

little.

more

synovial

fluid

–

Cartilage

than

from

110

(elbow)

around

elastic

hinge

joint

attached

insertion

they

and

movement

joints.

are

these

the

hinge

Muscles

Ligaments

through

A

dissecting

Remove

attached

manipulate

by

7.5.2

covers

the

end

bone

and

smooth

wear

and

tear.

so

of

it

bones

glides

at

moveable

over

the

joints.

ends

It

is

softer

protecting

the

bone

Synovial

joint.

Muscles

move

a

fluid

This

fluid

only

part

bone.

is

is

secreted

an

oily

contract,

of

your

Muscles

by

they

body,

cannot

the

liquid

synovial

that

do

not

muscles

push

expand.

contract

the

membrane

lubricates

bone

the

To

move

and

to

surrounding

about

shorten

move

the

joint.

it

or

and

back

to

to

pull

on

where Radius

it

started.

In

order

to

get

a

bone

to

move

back

another

muscle

is

Triceps

needed.

For

example,

there

are

two

muscles

that

move

the

forearm (relaxed)

and

they

biceps

form

and

type

muscle.

relaxes

and

of

is

Contraction

This

type

of

extended.

and

is

to

of

movement

triceps

is

is

the

the

the

of

7.5.3).

They

are

the

the

antagonist

triceps

raises

biceps

muscle,

muscle

extension

extensor

biceps,

muscle

and

the

is

the

forearm.

the

Insertion

flexor

triceps,

longer.

the

called

the

biceps

flexion

become

shortening

muscle,

(Figure

Humerus

called

happens

pulled

The

antagonist

shortening

this

pair

muscles.

movement

When

and

antagonistic

triceps

Contraction

This

an

and

the

muscle.

relaxes

and

is

lowers

arm

When

pulled

the

is

now

this

to

forearm.

happens

become

the

longer .

Origin Radius

Lever

Levers

action

are

the

most

efficient

way

of

moving

or

supporting

a

Triceps

load.

(contracted)

There

is

a

lever

action

in

every

moveable

joint

in

the

body.

Joints

act

Insertion

as

fulcrums.

provide

the

These

effort

are

to

the

points

move

about

which

a

lever

pivots.

Muscles

levers. Ulna

Levers

in

the

body

support

the

weight

of

the

body.

The

arm

acts

as Figure

a

lever

(Figure

fulcrum

of

the

arm,

and

is

of

the

held

minimises

example,

movement

KEY

what

muscle

for

7.5.4):

a

muscle

in

the

the

of

hand

effort

movement

457 mm

provides

the

of

is

the

the

needed

25 mm

hand

at

load.

to

of

the

effort,

The

move

the

end

the

the

the

is

7.5.3

the

load.

In

results

and

action

antagonistic

flexing

extending

(left)

(right)

the

a

lever.

E

POINTS

are

of

in

forearm

the

in

The

muscles

arrangement

biceps

of

joint

1

Joints

where

2

Ligaments

bones

meet.

L

attach

3

Fixed

and

bones

joints

tendons

are

together;

occur

both

tendons

where

there

tough

attach

is

no

where

there

is

movement

in

one

where

there

is

movement

in

three

tissues.

muscles

Ligaments

to

movement;

plane;

ball

bones.

hinge

and

joints

socket

joints F

planes

F

(rotational).

E

L

SUMMARY

=

=

=

Elbow

Biceps

joint

muscle

Forearm

and

weight

7.5.4

The

lever

arm:

Explain

2

State

3

hand

is

meant

locations

in

by

the

the

terms

body

of

fixed

hinge

joint

and

joints

synovial

and

ball

joint

F

effort

is

action

the

and

L

of

the

fulcrum,

is

E

is

load.

and

joints.

Describe

joint:

4

what

the

socket

in

QUESTIONS Figure

1

held

the

functions

cartilage,

Explain

how

of

ligament,

the

human

the

following

tendon,

forearm

in

muscle

is

a

movement

tissue

and

extended,

about

a

synovial

and

b

fluid.

flexed.

111

Unit

SECTION

1

2

Where

1:

in

4

Practice

Multiple-choice

the

human

body

exam

questions

is

urea

made?

6

Bones

are

attached

bladder

A

cartilage

B

kidney

B

ligaments

C

liver

C

synovial

D

stomach

D

tendons

Which

substance

is

not

in

the

urine

of

a

7

person?

A

glucose

B

sodium

C

D

Pairs

of

across

muscles

a

hinge

B

extensor

urea

C

flexor

water

D

skeletal

Excretion

is

the

A

dead

B

excess

C

undigested

D

waste

What

removal

from

the

body

of

8

Blood

is

products

of

when

the

muscle

forearm

Triceps

is

muscles

muscles

muscles

muscles

filtered

Which

part

collect

in

of

in

the

the

glomeruli

nephron

contracts

relaxes

after

A

Bowman’s

B

Collecting

C

Distal

D

Proximal

Urine

the

flows

pelvis.

passes

C

relaxes

contracts

D

relaxes

relaxes

Collecting

ducts

before

following

leaving

it

can

occurs

removed

is

reabsorb

leaves

the

when

from

secreted

permeability

a

is

ducts

ADH

not

of

to

the

water

kidney.

there

the

is

Which

excess

of

duct

tubule

convoluted

tubule

to

nephrons

of

be

is

the

structures

voided

remain

is

and

permeable

secreted

of

to

the

to

through

from

the

→

bladder

B

collecting

duct

→

urethra

C

ureter

D

urethra

→

bladder

→

ducts

to

→

bladder

is

ducts

112

not

secreted

remain

and

the

impermeable

the

ducts

to

collecting

to

into

which

urine

→

→

urethra

bladder

urethra

→

10

Which

of

the

following

organ

A

kidney

B

liver

C

lungs

D

skin

that

and

with

water.

ureter

it

correctly

the

and

excretes?

urine

bile

and

and

pigments

oxygen

carbon

pairs

metabolic

collecting

collecting

kidney

body?

duct

water.

decrease

the

collecting

substance

the

the

in

correct

A

excretory

collecting

from

Which

the

water

water.

ADH

kidney.

filtrate

from

body?

increase

secreted

permeability

D

the

the

glomerulus?

water.

C

in

capsule

convoluted

sequence

ADH

does

muscle

B

B

movement

as:

raised?

9

ADH

about

known

metabolism

contracts

A

bring

are

materials

happens

is

by:

heat

contracts

that

together

skin

A

urine

that

joint

antagonistic

ions

firmly

membranes

A

Biceps

5

questions

A

healthy

3

7

dioxide

an

waste

SECTION

11

a

2:

Short

Ammonia

waste

is

answer

questions

produced

product

of

by

their

all

animals

as

a

3.0

metabolism. ni

Explain

table

blood

this

is

shows

plasma

in

necessary.

(3)

the

composition

the

renal

artery,

aerU

The

urea

of

filtrate

in

2.5

eht

b

why

is

g/doolb

to

humans

md

converted

by

noitartnecnoc

produced

3

Ammonia

2.0

1.5

1.0

0.5

Bowman’s

capsule

and

urine.

0.0

0

−3

Substance

Concentration/g dm

5

10

15

20

25

30

Time/days Blood

in

plasma

Filtrate

renal

in

Urine

Figure

Bowman’s

artery

1

capsule

i Urea

0.2

0.2

20.0

Glucose

0.9

0.9

0.0

State

how

received

dialysis

evidence

Amino

0.05

0.05

9.0

9.0

0.0

many

from

times

the

man

treatment;

Figure

1

to

give

the

support

your

answer.

(2)

acids

ii

Mineral

Calculate

the

decrease

in

the

16.5

concentration

of

the

man’s

urea

in

the

ions

blood

Protein

82.0

0.0

from

end

Show

Four

of

the

substances

shown

in

dialysis

table

are

of

your

Describe

present

in

the

filtrate,

his

treatment

on

day

is

not.

(2)

and

the

20

in

amino

the

that

in

the

occur

blood

acids

are

Explain

the

changes

you

have

not

urine.

concentration

ions

is

higher

in

iii.

(3)

(2)

in

of

the

urea

urine

and

than

in

the

blood

c

Explain

12

a

in

the

renal

concentration

in

the

how

renal

filtrate

is

artery

of

urea

has

b

a

Distinguish

and

(3)

blood

higher

i

Make

arm

(1)

in

those

ii

the

kidney.

(4)

large

the

the

and

A

man

with

dialysis

shows

his

the

kidney

treatment

how

blood

start

the

for

his

20

received

days.

concentration

changed

of

failure

over

the

of

urea

days

iii

1

Draw

and

(2)

the

to

show

shoulder,

practice

examples

upper

following

on

joint,

radius,

(3)

your

hinge

scapula

diagram:

joint,

and

diagram

muscles.

sites

Label

of

the

ulna.

the

origin

biceps

two

and

(3)

and

muscles

insertion.

(3)

Explain

why

a

the

pair

movement

of

of

antagonistic

the

forearm

muscles

and

questions

can

be

just

one

muscle.

(4)

found

Total the

the

the

treatment.

not

on

plants

forearm.

your

their

requires

and

on

triceps

in

from

c

Further

of

regular

Figure

30

movements

diagram

of

socket

humerus, d

marks

animals.

bones

and

Label

ball

between

of

a

major

than

vein.

formed

25

mineral

filtrate.

The

the

(3)

Total The

in

over

days.

described present

changes

concentration

(2) iv

Glucose

iv

20.

working.

but the

protein

iii

until

the urea

ii

of

why iii

i

start

0.0

the

Explain

the

accompanying

15

marks

CD.

113

8

Irritability

8.1

Coordination

and

survival

LEARNING

At

the

end

should

be

In

order

in

its

in

the

to

survive

of

this

able

topic

you

an

to:

environment

define

the

terms

(sensitivity),

response,

and

•

their

and

environment.

organism

sensitivity,

•

in

habitat

each

organism

needs

to

sense

changes

OUTCOMES

as

is

a

A

make

response

direct

the

suitable

result

ability

to

of

is

a

detect

a

responses.

change

stimulus.

stimuli

in

A

stimulus

position

or

Irritability,

and

respond

a

change

behaviour

also

to

is

known

of

as

them.

irritability

Figures

stimulus,

receptor,

and

effector

8.1.1

to

8.1.6

show

some

examples

of

responses

of

plants

animals.

coordinator

explain

how

effectors

are

receptors

involved

and

in

coordination

•

explain

stimuli

how

are

responses

important

to

for

survival.

Figure

8.1.2

seedling

roots

Touch/stimulus

stem

are

is

This

kidney

germinated

growing

growing

responds

to

in

the

bean

dark.

downwards

upwards

as

The

and

the

the

plant

gravity. Figure

8.1.4

sensitive

This

to

Earthworms

vibrations

earthworm

pecking

at

the

has

soil

in

the

detected

showing

are

ground.

a

an

bird

escape

response.

Figure

8.1.1

mimosa

leaflets

the

fold

petiole

parallel

Lightly

(‘sensitive’

to

up.

Keep

bends

the

or

touch

‘shy’

the

plant)

touching

downward

leaves

and

the

so

leaf

the

of

the

and

leaf

is

stem. Figure

8.1.3

touched

of

the

leaf

trapped.

plant

114

the

in

and

There

the

Venus

sensitive

fly

hairs

trap.

on

has

been

is

drawing

a

questions

at

well

and

of

the

The

the

a

end

fly

surface

truly

Figure

whole

of

Unit

8.1.5

octopus

8.

match

This

changes

its

its

Caribbean

reef

appearance

surroundings.

to

Receptors

and

effectors LINK

In

each

of

these

cases

a

stimulus

is

detected

by

receptors.

These The

detect

certain

stimuli

and

send

information

about

them

to

roles

effectors

which

carry

out

the

response.

Communication

between

receptors

is

Receptors

energy

of

the

in

function

animals

stimuli

of

are

such

a

travel

towards

middle

fluid

the

ear

that

Some

along

of

Venus

Other

causes

light

or

specialised

movement

receptor

cells;

pigments

Effectors

nerves,

animals

plant

are

cells

into

that

convert

electrical

ducts

onto

responses

starch

to

are

touch

surface

in

the

impulses

detected

8.1.6

of

of

to

such

the

a

Identify

each

bend.

as

in

Figures

answer

detect

are

no

where

elongate

by

elongate

more

where

and

glands.

parts

of

other

growth

to

When

the

in

cool

responses

cells

side

on

so

faster

the

the

move

upper

side

of

bends

of

cells

cells

the

the

the

ways:

and

and

light

carry

blood;

body

down

apical

one

8.1.1–8.1.5,

question

or ,

when

the

out

Irritability

is

in

A

response

organism;

in

it

the

is

effectors

a

case

of

hot.

are

the

organ

petiole

lower

in

grow

The

side

of

bends

the

or

away

in

evening.

faster

the

stem

upwards

opposite

of

a

than

Here

root

from

the

T o

movement

on

the

is

the

Sensory

hair

cochlea

in

(×

from

inner

the

ear

600)

to

this

lower

caused

by

petiole.

the

the

ability

to

make

responses

to

stimuli

that

are

environment.

is

a

change

in

position

or

behaviour

of

8.1.7

If

an

responses

have

survival

insect

detect

stimuli,

effectors

these

hairs

between

carry

out

systems,

receptors

such

as

the

and

effectors

is

the

role

Venus

nervous

List

all

b

List

the

the

different

effectors

how

ensure

fly

within

trap,

20

the

of

trap

to

seconds.

digest

system.

secreted

glands

all

by

the

over

the

insect

the

red

surface

15).

QUESTIONS

a

Explain

two

leaf

of

(×

SUMMARY

a

responses;

are

coordination

on

value.

Enzymes

communication

touches

an

shuts

Receptors

to

cells

the

side

morning

achieve

those

8.1.6

cells

the

2

then

release

of

1

and

2.

by

Figure

3

of

organism

POINTS

changes

2

value

each

by

others

meristems.

side

move

downwards

the

the

on

also

downwards.

on

as

plant

Leaves

and

leaf

If

other ,

occurs.

light

growth

KEY

1

the

the

than

growth

known

water .

to

movement.

stimulated

body

into

elsewhere

surface

occurs

absorbing

most

intercept

growth

survival

specialised

Figure

regions

the

response

temperature.

that

in

bones

nerves,

FOCUS

waves

movement

Figure

of

and

There

three

into

endings

hormones

lead

body

discussed

grains.

move

release

that

the

are

see

sound

the

waves

can

the

their

funnels

causing

obvious.

muscles

glands

into

glands

by

you

detect

over

less

stimuli

contract

Some

substances

sweat

gravity

muscles

response.

are

ear

sound

simply

that

hairs

instead

and

in

have

vibrates,

that

are

skin

receptors

outer

convert

‘hairs’

the

The

which

and

the

in

traps

plant

cells.

receptors

those

fly

drum

move

animal

some

Most

ear

to

nerve

and

are

8.2.

STUDY that

receptors

plants

coordinator.

generally

as

in

and in

effectors

of

effectors

each

of

in

stimuli

plants

the

that

and

are

mentioned

in

this

topic.

animals.

responses

in

Figures

8.1.1–8.1.5

helps

survival.

115

8.2

Plant

Responses LEARNING

At

the

end

should

be

describe

stems

to

of

this

able

•

relate

the

and

light,

to

topic

responses

roots

these

Plant

responses

depend

Plant

responses

can

of

and

Seeds

gravity

then

to

of

plants

in

cress,

are

soaked

arranged

•

to

results

investigations

that

of

in

A

Kept

B

Put

into

C

Put

into

D

Put

onto

as

in

the

plants

piece

every

The

A

an

B

a

in

15

investigated

or

stimulus.

with

seedlings

of

plants,

such

as

peanuts.

in

water

in

investigations

The

have

so

that

they

1

to

start

to

germinate.

They

are

3.

responses

of

seedlings

to

light

been

grown

in

the

dark

are

put

in

conditions

A

to

D:

dark.

with

environment

Seedlings

growing

from

side

one

in

revolving

groups

of

uniform

with

light

light

from

(light

one

from

side

all

around).

only.

The

D

to

in

give

light

must

all

from

one

experience

side.

the

same

conditions

factors.

Figure

light

to

8.2.2

all

is

a

sides

are

continue

taller

seedlings

are

continue

not

to

than

as

grow

those

clinostat

of

to

tall

grow

as

upwards,

in

the

–

it

revolves

once

seedlings.

upwards,

those

leaves

are

yellow,

leaves

are

green,

B.

in

A.

C

The

seedlings

grew

as

in

Figure

8.2.1.

D

The

seedlings

grew

as

in

Figure

8.2.2.

Plants

have

plant.

pigments,

They

the

The

The

results

results

use

are

shown

3

water.

are

The

shown

starch

Downward

a

The

occur

light.

response

on

one

response

of

side

Chemicals

by

of

diffuse

stimulating

roots

seedling

and

roots

through

more

shoots.

to

gravity

in

in

Figure

8.2.3.

response

of

seedling

shoots

to

gravity

in

dark

Roots

of

2

to

detect

the

dark

Investigation

the

which

coordinate

growth

Investigation

in

to

with

light

only

growing

A

other

apparatus

seedlings

elongation

clinostat

disc

results

The

the

Seedlings

and

minutes

seedlings

116

be

corn

environment

an

seedlings

8.2.2

1

temperature

The

Figure

the

tables.

of

8.2.1

of

of

The

Figure

direction

make

investigations

responses

record

the

their

Seedlings

how

controlled

on

the

habitats

plant

gravity

of

seedlings

responses

beans,

Investigation

outline

and

you

to:

touch

behaviour

•

light

OUTCOMES

peas, •

responses

in

grains

growth

Growth

has

into

Figure

inside

cells

survival

the

soil

8.2.4.

to

value

also

detect

as

the

roots

anchors

direction

grow

the

of

towards

young

plant.

gravity.

a

source

Shoots

Moist

Clinostat

cotton

Petri

dish

wool

Result

after

2

days

Control

Figure

may

the

8.2.4

not

be

Seedling

pointing

direction

of

shoots

grown

upwards.

gravity

and

in

the

They

dark

have

respond

by

a

similar

growing

system

to

upwards

detect

towards

the

Figure

source

of

light

for

8.2.3

Seedling

the

Response

Plants

show

plant)

and

that

are

is

of

tendrils,

on

observed

time

roots

direction

to

of

fly

response

trap,

on

such

the

by

(time-lapse

When

types

Venus

dependent

dependent

best

the

as

to

touch.

example,

direction

those

position

taking

for

of

of

the

Mimosa

show

growth

of

the

morning

stimulus

observations

or

responses

stimulus.

glory,

is

(Figure

The

slower

8.2.5).

photographs

at

and

They

are

intervals

of

photography).

touch

avoid

Plant

a

as

an

the

they

responses

seed

object

in

the

obstruction.

push

are

germinates

soil

In

they

this

grow

way

in

a

roots

different

use

their

way

particularly

it

can

be

through

noticeable

orientated

in

the

in

air

less

young

any

spaces

in

energy

plants.

direction,

it

the

8.2.5

Use

soil.

A

plant

The

position

kept

leaves

reach

the

in

so

the

remain

light

the

root

dark

will

yellow

source.

grows

continue

and

This

downwards

is

do

to

not

to

grow

unfurl

ensure

or

that

and

the

needs

shoot

upwards

expand

the

most

effectively

–

growing

through

the

at

a

until

seedling’s

soil

to

reach

leaves

unfurl

and

and

grows

over

fast

rate.

1

a

they

energy

the

Make

a

results

table

State

POINTS

Describe

to

Figure

responses

are

fast,

such

as

the

closing

of

of

to

fly

trap;

most

plant

responses

are

slow

because

growth

Investigation

three

the

ways

Plants

3

Plant

the

respond

to

responses

the

the

direction

of

light,

gravity

and

in

to

have

light.

responses

as

of

shown

the

in

8.2.3.

Explain

the

advantages

using

the

clinostat

effect

of

are

investigated

each

stimulus

under

can

be

controlled

Plant

growth

light,

carbon

responses

dioxide,

ensure

water

that

and

to

in

3.

conditions

Explain

and

3

why

are

Investigations

set

up

in

the

2

dark.

determined.

plants

ions

1

touch.

5

4

1

responses.

4

so

1.

in

seedlings

gravity

Investigations

2

the

they

of are

record

the

3 Venus

hours.

expand.

roots

plant

a

it

light;

2

Some

several

how

is

responded

1

stimulate

QUESTIONS

Investigation

KEY

to

observe

to

which

then

pencil

upwards.

b

used

a

tendril

When

SUMMARY change

in

(‘sensitive’

sudden

Figure

for

grown

dark

touch

two

the

not

response

to

roots

photosynthesis.

for

gain

their

sufficient

survival.

Explain

plants

light,

the

of

advantages

these

gravity

to

responses

and

to

touch.

117

8.3

Invertebrate

The LEARNING

responses

the

end

should

•

be

of

this

able

describe

the

temperature

explain

how

topic

school

you

responses

to

light

and

to

of

terrestrial

lab

with

and

some

intensity,

•

moving

invertebrates,

earthworms,

simple

can

apparatus.

be

such

as

woodlice,

The

investigated

responses

in

that

the

they

show

directly

towards

•

changing

their

•

changing

direction

speed

in

or

away

from

response

to

a

the

source

of

intensity

a

of

stimulus

the

stimulus

moisture with

the

intensity

of

the

stimulus.

investigate The

behaviour

millipedes

involve

to:

invertebrates

•

small

OUTCOMES maggots,

At

of

responses

using

way

in

which

results

are

recorded

is

determined

by

the

type

of

choice response

shown

by

the

invertebrates.

chambers

•

explain

how

to

carry

out Investigation

controlled

investigations

The invertebrate

apparatus

Place

the

invertebrates

and

they

are

like

described

investigations

cool

you

damp

less

carry

the

a

of

invertebrates

to

light

8.3.1

is

arranged

so

that

the

desk-lamp

is

from

Put

active

one

the

end

of

marked

maggot

the

A4

exactly

tray,

shining

paper

at

in

the

at

a

shallow

angle

tray.

likely

out

ones

live

habitats

to

in

dark,

where

dehydrate.

investigations

described

on

you

should

take

harm

the

the

cover

over

the

the

centre

of

tray.

Mark

the

the

small

position

circle

of

and

the

cover.

in

Start

timing

circle.

Mark

seconds,

If

the

as

soon

this

mark

the

maggots

as

the

position

head

on

the

maggot’s

are

very

of

the

beaker

position

lively,

five

maggot

with

a

again,

seconds

crosses

small

using

may

be

the

a

the

‘a’.

inner

Every

same

better

10

symbol.

interval.

here,

care

in

a

suitable

table,

across

which

sector

(+ve,

−ve,

or

neutral)

not the

to

Figure

transparent

Record, then

tray.

one

centre

If

response

FOCUS place

these

in

100 mm

along

The

The

responses.

about

STUDY

1

on

maggot

left

the

outer

circle.

Continue

marking

its

position

at

animals. regular

Repeat

a

new

cover

Place

the

these

the

the

until

steps

symbol

in

(‘b’,

same

it

reaches

until

‘c’,

you

‘d’,

position

transparent

relative

T able

Positive

intervals

position

the

have

etc.

for

cover

of

the

on

for

a

of

the

recordings

each

each

lamp.

edge

marked

from

one).

T ake

10

paper.

maggots:

care

to

place

use

the

trial.

large

sheet

Make

a

of

table

paper,

for

and

your

mark

results

as

in

8.3.1.

response

T able

8.3.1

−1

Sector Neutral

Neutral

response

response

Number

of

Mean

speed

at

2

second

intervals/mm s

maggots

2

4

6

8

10

1

1.75

0.75

1.00

0.00

0.00

15

12.40

9.00

8.30

5.50

3.50

4

1.56

0.59

0.35

0.25

0.00

Positive

Negative

response

Negative

Neutral

Tray

Sheet

of

A4

paper

This Figure

8.3.1

Apparatus

for

method

investigating

Cheverton responses

to

118

light

of

invertebrates

and

Figure

8.3.1

were

provided

by

the

late

John

Investigation

Draw

in

a

the

a

line

bowl

small

2

The

across

of

cold

the

middle

water

beaker ,

invertebrate

response

not

inside

from

the

the

of

of

the

the

invertebrates

base

tap.

temperature

beaker

and

of

a

Record

of

the

record

to

beaker .

the

air

water

how

temperature

Place

the

beaker

temperature

bath.

often

the

Put

an

animal

in

T able

8.3.2

T emp.

Number

/°C

millipedes

active

line

in

3

line

bowl

in

to

T able

a

given

give

8.3.2

Figure

different

shows

temperature

Choice

period

was

air

some

of

time.

Use

hot

temperatures

results

repeated

after

with

in

and

the

cold

and

ice

in

halves

that

versus

dry,

shows

have

a

choice

this

different

different

chamber.

conditions,

versus

dark

chloride

a

low

in

and

damp.

silica

humidity;

the

used

or

combinations

air

to

gel,

cotton

light

drying

placed

immediately

give

A

and

of

This

such

procedure.

in

wool

be

light

Bench

in

such

such

lower

soaked

above.

dark

agent,

the

used

to

versus

as

as

light

give

dark,

water

gives

and

and

anhydrous

compartment

lamps

3

mean

4

3

6

4

20

9

8

7

8

25

12

15

12

13

30

16

17

15

16

40

3

5

4

4

Each

millipedes.

can

as

conditions

2

10

two

damp Damp

and

minutes

the

chambers

8.3.2

the

beaker .

following

three

water

times

crossed

crosses 1

the

of

a

Hole

Woodlouse

half

the

to

put

in

woodlice

calcium

gives

higher

black

dry

paper

air

with

humidity

can

be

compartments. Wet

Woodlice

can

of

be

be

(Figure

collected

woodlice

counted

T able

8.3.3

in

at

8.3.3)

in

a

each

released

number

of

into

ways,

compartment

timed

shows

are

or

the

for

the

choice

example

number

chamber.

the

that

total

are

Results

number

moving

tissues

Transparent

cover

Gauze

can

Dr ying

agent

intervals.

some

data

from

a

student’s

choice

Figure

8.3.2

A

choice

Figure

8.3.3

The

chamber

chamber

investigations.

T able

Time/

8.3.3

Investigation

1

Investigation

2

min Number

each

of

woodlice

in

Number

area

in

Light

each

Dark

of

woodlice

moving

area

Dry

Humid

0

10

0

5

5

2

6

4

7

1

4

3

7

3

2

6

3

7

1

0

8

1

9

0

0

10

1

9

0

0

KEY

1

Invertebrates

Choice

respond

and

the

to

light,

moisture.

chambers

investigate

SUMMARY

woodlouse

POINTS

temperature

2

common

are

used

responses

to

of

QUESTIONS invertebrates

to

these

three

stimuli. 1

Draw

graphs

conclusions

of

the

can

results

you

make

shown

from

in

the

T ables

8.3.1–8.3.3.

What

3

results?

Small,

terrestrial

invertebrates, 2

Explain

how

to

use

choice

chambers

to

investigate

woodlice responses

of

small

invertebrates

to

Explain

the

terrestrial

survival

value

invertebrates

of

to

the

light,

that

live

as

in

or

light. on

3

such

the

responses

shown

temperature

and

by

small

moisture.

the

soil

are

dehydration

damp

and

prone

and

cool

to

prefer

conditions.

119

8.4

Nerves

and

the

brain

Coordination LEARNING

OUTCOMES

Animals At

the

end

should

•

be

outline

of

this

able

the

topic

to:

structure

of

•

a

nervous

nervous

including

•

describe

the

the

•

an

outline

how

about

•

roles

of

of

the

brain

neurones

a

systems:

consisting

system

of

nerve

consisting

of

cells

as

adrenaline

and

insulin,

organs

into

the

that

secrete

hormones,

blood.

Figure

brain

8.4.1

and

shows

spinal

nerves

that

the

cord

structure

form

spread

the

of

the

human

central

throughout

the

nervous

nervous

body

system.

system

from

the

The

(CNS);

CNS

form

all

the

receptors,

and

effectors

simple

The

reflex

nervous

system

(PNS).

bring

responses

describe

system

endocrine

peripheral neurones

coordination

system

parts

the •

two

the

such human

have

you

action.

cranial

and

surrounded

cells

that

by

send

distances.

spinal

tough

nerves

fibrous

electrical

There

are

are

bundles

tissue.

impulses

three

types

many

Neurones

to

of

of

and

from

nerve

are

the

cells

specialised

CNS

over

nerve

long

neurone:

cranial

• brain

Sensory

neurones

conduct

electrical

impulses

from

sensory

cells,

ner ves

such

as

rods

and

cones

in

the

eye,

to

other

neurones

in

the

CNS.

spinal spinal

•

Motor

neurones

conduct

electrical

impulses

from

the

central

ner ves cord

nervous

glands,

•

Relay

system

such

are

storing

The

The

effectors.

sweat

are

between

other

types

information

These

glands

only

and

found

sensory

of

and

for

the

in

and

neurone

effectors

adrenal

the

CNS

motor

in

the

decision

are

muscles

and

they

neurones.

CNS

brain

is

the

body’s

from

functions

main

receptors,

instructions

certain

for

transmit

In

addition,

integrating

to

effectors.

(Figure

centre

decisions,

Parts

of

the

which

stores

brain

are

receives

memories

EXAM

The

human

nervous

and

specialised

for

8.4.2).

b

Cerebrum

Cerebrum

8.4.1

and

making.

coordination

makes

a

Figure

and

glands.

brain

information

sends

as

neurones

information

there

to

system

TIP

Hypothalamus

Do

no t

confus e

the

spinal Medulla

co rd

with

the

spin e.

Pituitar y

gland

Oblongata Medulla

See

7 .4

to

be

sure

Cerebellum

of

Cerebellum

the

Oblongata

differe nce.

Figure

8.4.2

The

a

120

brain

left

side

showing

of

the

the

brain,

location

b

of

vertical

the

four

section

regions

through

listed

the

in

brain.

T able

8.4.1.

T able

8.4.1

Functions

of

the

parts

of

the

brain

KEY

Region

of

the

POINTS

Functions

1

brain

The

nervous

systems Conscious

Cerebrum

the

left

right

Coordination

of

Memory,

and

of

Interpretation

hemispheres

voluntary

learning

Understanding

cerebral

endocrine

the

thought body’s

consisting

and

coordinate

and

of

actions

2

reasoning

language

and

sensory

activities.

control

of

information

brain

and

comprise

speech

from

The

the

spinal

cord

central

nervous

system.

sense

organs 3

Cerebellum

Receives

the

ear

and

information

and

from

from

stretch

balance

receptors

receptors

in

in

and

muscles

balance,

posture

and

and

controls

body

content

of

the

temperature

release

of

The

Medulla

ADH

and

FSH

(see

9.3)

to

and

hormones

Controls

control

LH

many

to

cerebrum,

medulla

from

the

the

kidney

control

involuntary

the

(see

•

rate

•

heart

and

depth

the

and

of

peristalsis

–

such

cycle

5

A

reflex

action

of

simple

hot,

a

person

there

is

a

touches

very

a

quick,

hot

response

a

controlled

stimulus

think

This

is

an

working

example

of

stimulus

of

a

movement

of

food

in

a

Reflex

actions

require

object

without

response

realising

that

the

that

it

is

reflex,

which

is

an

person

involuntary

impulses

receptor

sensory

Define

and

fast,

are

protective.

QUESTIONS

the

of

simple

reflexes

neurone

in

CNS

neurone

motor

this

are

and

2

Make

a

in

the

protective.

is

Make

receptors

A

used

in

tap

the

spinal

to

on

check

muscle

in

leg.

the

that

knee

tendon

cord.

neurone

lower

action

drawing

system

to

and

use

distinguish

and

the

of

the

colour

between

PNS.

a

large

label

8.4.1

their

drawing

the

parts

and

of

the

from

annotate

functions.

reflex

the

nervous

system

is

Describe

In

that

this

the

upper

it

and

send

reflex

stimulates

Try

stretches

a

leg.

tendon;

impulses

there

motor

The

a

is

no

along

relay

neurone

effector

this

a

stimulates

sensory

neurone,

that

muscle

the

response

to

each

functioning

of correctly.

involuntary

simple

CNS

brain,

4 reflex

simple

neurone

with

jerk

neurone,

(effector)

arm)

like

terms

receptor,

reflex

T able

a

are

conscious

action.

3

the

brings

in

impulses muscle

to

a

does

is:

response

sensory

from

muscle

response.

no

effector,

temperature

(withdrawal

the

a

so

coding

to

which

about

nervous

This

to

the

reflexes

relay

Knee

impulses

receptor

canal

automatic

simple

events

object)

Many

by

series

about.

sequence

(hot

in

pressure

1

The

to

breathing

blood

SUMMARY not

an

automatic

decisions When

is

as:

6

Coordination

of

brain.

(effector), alimentary

are

regions

7.3)

sensory •

cerebellum

oblongata

main

transmitting rate

system.

pituitary

menstrual

actions,

of

neurones oblongata

nervous

the

the

blood

the

gland:

from

comprise

brain

and

three

Controls

the

movement

and

water

from

nerves

cord

peripheral

of

4

Monitors

nerves

spinal

spinal

tendons

Coordination

Hypothalamus

Cranial

neurone

so

conducts

contracts

the

following

a

touching

b

a

impulses

to

the

stimuli:

stretch

bright

the

a

very

light

hot

object

shining

into

eye

move c

a

piece

d

an

of

grit

in

the

eye

see! insect

bite.

121

8.5

The

The LEARNING

eye

the

end

should

be

of

this

able

topic

describe

the

to

to:

structure

of

with

focusing

you

light

brain

•

and

each

state

the

functions

Rods

how

images

in

by

the

define

the

•

describe

organs.

extra

It

contains

protecting

optic

the

structures

eye

sensory

nerve.

The

(Figure

that

receptor

8.5.1).

neurones

brain

are

cells

to

involved

in

Receptor

conduct

interprets

all

in

the

moving,

cells

respond

impulses

the

to

impulses

the

that

to

form

an

image

of

what

we

are

looking

it

at.

and

at

cones

the

are

back

of

highly

the

specialised

eyeball.

Rods

sensory

detect

cells

light

located

of

low

in

the

intensity

are

used

for

night

vision.

They

need

vitamin

A

to

function

eye

term

how

of

stimulating

the

properly

•

sense

are and

formed

our

of

part

explain

of

number

the

retina •

a

and

via

receives

eye

one

OUTCOMES retina

At

is

eye

(see

5.7).

Cones

are

only

stimulated

by

light

of

high

intensity

accommodation

focusing

is

achieved.

so

only

to

different

from

function

these

receptors

brain

so

in

daylight.

wavelengths

three

in

the

they

types

fovea

also

of

of

cone

are

give

There

light.

to

cones.

us

acute,

are

The

three

brain

give

us

Each

our

has

detailed

types

that

interprets

colour

its

own

respond

best

information

vision.

neurone

All

to

the

the

vision.

Choroid Ciliary

muscle full

changes

thickness

of

of

black

absorb lens

when

pigment

to

the light

and

stop

reflection

focusing Vitreous

jelly-like

the

humour

substance

internal

Conjunctiva

which

pressure

in

maintains

the

eye

and

its

shape

Retina

inner

light-sensitive

layer

which

contains

Cornea rod

Aqueous

watery

cone

humour

liquid

cells

that

cells

that

front

of

in

detect

dim

light

colour

and

and

details

filling Yellow

the

work

the

spot

or

fovea

eye Pupil most

sensitive

Blind

part

of

the

retina

spot

Lens point can

change

its

shape

light

onto

the

where

the

optic

nerve

attaches

to to

focus

the

eye;

no

light-sensitive

cells

here

retina

Iris

controls

light

the

intensity

entering

of

through Optic

the

nerve

pupil carries Suspensory

ligaments

hold

in

the

lens

tough,

Figure

8.5.1

A

horizontal

section

through

the

white,

When

horizontal

includes

blind

section

both

spot.

includes

blind

impulses

brain

layer

formation

light

A

the

vertical

either

spot

or

of

the

fovea

the

the

section

fovea

neither

eye

and

of

or

the

them.

focused

travelling

relied

of

the

we

on

enters

lens

as

it

the

passes

through

the

world

see

light

122

the

eye

it

is

focused

onto

the

retina.

Most

light

FOCUS is

A

protective

nerve

to

eye

Image

STUDY

away

Sclerotic

place

sharp

focus

around

light.

from

air

to

The

Figure

Each

one

and

focus

us.

images.

the

passes

the

cornea

through

the

now

light

lens

medium

to

enters

we

shows

has

This

a

a

is

see

the

how

a

fine

the

refractive

another

it

because

denser

would

provides

8.5.2

medium

cornea.

is

it

medium.

very

If

we

blurred

focusing

cornea

index

refracted

was

so

and

and

or

image

that

the

when

‘bent’.

Looking Light

on

Light

reflected

person

in

all

off

rays

the

are

at

a

distant

object

focused

retina

the

directions All

the

these

light

two

rays

enter

within

the

eye

The

and

ring

the

of

ciliar y

lens

Figure

is

muscle

pulled

8.5.3

relaxes

into

The

image

is

Figure

8.5.2

as

they

air

into

pass

the

Formation

(upside

from

brain

cornea

of

an

image

of

an

down)

–

interprets

image

the

object

at

on

from

an

the

object

far

eye

at

a

near

object

the

the

right

a

shape

inverted Looking

(bent)

thin

Focusing

away

refracted

a

way

up

distance

from

the

eye

Accommodation

Accommodation

is

the

term

used

to

describe

the

changes

that The

occur

in

the

eye

enters

the

eye

image

clearly.

when

it

must

focusing

be

on

refracted

far

and

(bent)

near

so

objects.

that

we

As

can

light

see

and

ring

the

call

this

focusing.

About

60%

of

the

ciliar y

muscle

becomes

refraction

8.5.4

Focusing

light

rays

The

lens

can

recoil.

and

is

is

done

by

surrounded

The

shape

suspensory

the

by

of

cornea

elastic

the

ligaments

lens

(see

and

tissue

is

the

rest

which

controlled

Figure

is

can

by

done

be

the

by

the

and

at

a

distant

KEY

the

ciliary

suspensory

elliptical

the

in

muscles

1

8.5.1).

The

eye

the

object

lens

(thin)

and

focus.

relax.

ligaments

shape.

focused

The

The

lens

tightly

Light

on

does

pressure

rays

the

not

(or

are

retina

need

of

the

taut)

so

the

refracted

(Figure

to

fluids

do

as

lens

they

8.5.3).

too

inside

much

is

the

eye

pulled

pass

The

as

into

an

retina

2

from

each

point

are

nearly

parallel

when

they

enter

the

Light

and

is

is

a

near

ciliary

The

the

muscles

suspensory

elastic

spherical

looking

lens

(fatter).

at

needs

the

to

contract

around

Light

distant

do

The

the

eye

to

are

the

rays

counteract

not

lens

are

object.

more

control

(Figure

of

the

accommodation

pulled

recoil

near

as

the

the

and

so

refracted

The

focusing

cannot

clearly

see

cones.

(bent)

the

as

it

cornea

Accommodation

of

the

is

the

image

lens

on

the

to

form

retina.

a

For

pressure

become

the

lens

more

object

light

is

in

slack.

becomes

than

rays

inside

they

focus.

are

the

This

eye.

lens

lets

the

more

were

This

as

is

are

thin.

and

For

the

the

taut

suspensory

slack

when

time

diverging

objects

ligaments

suspensory

and

near

the

objects

ligaments

lens

much

are

fatter .

the

they

QUESTIONS

8.5.4).

shape

is

on

of

lens.

SUMMARY enter

full

object

ligaments

tissue

is

sense

light

eye.

distant

The

which

through

the

sharp at

complex

focuses

refracted

focusing

Looking

a

light 3

rays

and

passes

object

the

is

that

pulls

through

distant

focusing

object

eye

POINTS

rods The

an

the

muscles

organ

Looking

to

lens.

stretched

ciliary

on

of close

the

contracts

rounder

the Figure

We

of

lens

of

another

where

the

lens

reflex.

you

are

by

This

the

too

going,

ciliary

is

you

muscles

protective

will

–

damage

in

if

you

yourself.

1

Use

the

Figure

information

8.5.1

showing

parts

of

to

the

the

in

make

a

functions

table

of

the

eye.

123

8.6

Eye

defects

pupil

Eye LEARNING

the

end

be

of

this

topic

an

able

describe

the

the

and

causes

that

long

is

too

sight.

short

If

you

or

a

are

lens

that

is

not

long-sighted

convex

then

objects

close

to:

causes

corrective

long

eyeball

you

to

•

reflex

defects

enough should

the

OUTCOMES

Having At

and

and

measures

short

sight

for

and

for

the

eye

are

to

sight

using

by

lenses

a

blurred

focused

point

(Figure

and

as

out

they

of

reach

converging

or

focus

the

because

retina.

convex

the

light

Opticians

lenses

in

rays

correct

spectacles

or

are

not

long

contact

8.6.1).

glaucoma Short

•

describe

the

pupil

sight

is

caused

by

having

a

long

eyeball

or

convex.

and

If

out

retina.

you

of

are

focus

Opticians

(Figure

short-sighted

because

correct

the

then

light

short

distant

lens

rays

sight

are

with

objects

focused

cur vature

enough

or

is

not

eyeball

that

is

too

Overcome

(convex)

objects

8.6.1

Glaucoma

obstructs

supplies

of

yellow

the

by

the

lenses

the

people

the

are

in

eyes

or

and

often

their

often

corrected

of

by

in

The

unaware

of

peripheral

a

the

of

pressure

eye.

converging

the

focused

cloudy

in

the

nerve

start

later

there

and

which

of

is

are

are

a

dying;

those

from

poor

develops

children

appearance

can

retina

reducing

because

as

objects

the

eyeball

and

usually

Some

far

on

lenses.

this

increases

changes

vision.

and

nerve,

retina

Glaucoma

the

in

optic

Neurones

periphery

near

focused

pressure

supplying

the

have

using

increased

nutrients.

the

fovea.

fluids

are

retina

converging

vessels

supply

spot

is

result

oxygen

of

sight

blood

that

deterioration

their

Long

is

the

those

drainage

and

of

concave

lenses

be

and

front

or

shor t

Both

the

blurred

great

too

behind

first

in

diverging

Near

Figure

are

8.6.2).

Lens

124

a

reflex.

slowly

slow

born

very

with

watery.

it

Lens

cur vature

eyeball

too

is

too

great

or

long

Far

objects

front

of

are

the

focused

in

retina Figure

Overcome

(concave)

by

8.6.3

Children

should

have

their

diverging

eyes

lenses

age

tested

to

from

make

defects

are

a

sure

young

that

detected

any

and

treated.

Both

be

Figure

Pupil

Move

dark.

8.6.2

from

For

a

going

a

moment

the

a

very

while

is

from

a

bright

you

dark

you

are

adjustments

iris

contract

contract

Sensory

along

sight

corrected

by

using

and

diverging

far

on

objects

the

can

retina

lenses.

reflex

–

These

Short

near

focused

to

to

the

optic

place

almost

are

nerve;

entering

by

by

the

motor

the

light

in

from

neurones

iris.

the

very

For

adjust.

muscles

radial

controls

to

reverse

eyes

Circular

retina

transmit

the

bright.

your

pupil;

reflex

the

somewhere

about

until

the

of

simple

impulses

into

think

somewhere

diameter

A

walk

Now

muscles

diameter.

transmit

and

much.

blinded

made

its

place

see

and

decrease

increase

neurones

well-lit

cannot

muscles

them.

the

impulses

in

Figure

8.6.4

brain

to

the

Constriction

of

protects

the

retina

damage

by

along

STUDY

another

one

of

the

cranial

lenses

are

thicker

in

the

middle

than

they

are

at

so

they

are

convex

in

shape.

Diverging

lenses

are

POINTS

Defects

edges

than

they

are

in

the

middle

so

they

are

in

concave

caused

that

they

‘cave

(long

sight)

drainage

eye

Define

short

the

terms

accommodation,

glaucoma,

long

sight

and

sight

Explain

3

Make

Muscles

of

in

diameter

the

how

opticians

correct

long

and

short

the

flow

light

chart

diagram

to

show

how

the

pupil

reflex

the

of

when

you

walk

from

a

dark

room

Explain

the

the

eyes.

purpose

of

constricting

and

iris

the

that

retina

the

control

pupil

enters

the

into

bright

dilating

the

from

light.

the

pupil

the

altering

eye.

protects

damage

Dilating

the

by

pupil

light. increases

4

in

is bright

controlled

fluid

sight.

the

a

and

poor

(glaucoma).

Constricting 2

sight

and

QUESTIONS

2

1

can

mis-shapen

in’). short

SUMMARY

by

in eyeballs

(remember

eyesight

thicker be

the

in

the 1

shape

light

reflex.

FOCUS

Converging

at

simple

nerves.

KEY

edges

bright

pupil

from

iris

this

muscles

the

pupils

in

the

the

retina

vision

in

to

light

reaching

enable

dark

better

conditions.

125

8.7

Drugs

The LEARNING

term

applied

At

the

end

should

be

of

this

able

topic

define

•

state

the

term

are

drug

different

drugs,

to

any

which

substance

any

alters

a

that

chemical

is

taken

into

reaction

in

the

the

body

body

or

or

pathogen.

including

medicinal

be

divided

Most

into

medical

others

are

those

drugs

freely

are

that

are

for

available

available

‘over

medical

only

the

on

use

and

those

prescription

counter’

from

that

from

a

pharmacies,

categories

legal

and

and

supermarkets.

Non-medicinal

drugs

which

are

used

and for

illegal,

skin

with

can

not.

shops of

refers

the

to:

doctor; the

to

interferes

you

Drugs

•

drug

OUTCOMES

the

pleasure

that

they

are

supposed

to

give

are

often

known

as

nonrecreational

drugs.

Some,

such

as

caffeine

and

alcohol,

are

part

of

medicinal everyday

•

discuss

the

use

and

life

medicinal

drugs,

and

in

discuss

social

drug

and

the

and

effects

including

of

illegal

and

Medicinal

as

cocaine,

heroin

and

as

of

they

are

illegal

considered

drugs

or

a

risk

involved

in

to

health.

their

People

production,

supply

are

prosecuted

by

law

enforcement

agencies.

drugs

heroin Some

drugs

much

longer,

are

prescribed

for

short

periods

of

time

and

some

for

alcohol.

abused

obtained

drug

drug

Sedative

or

Examples

Effects

Valium,

Slows

Librium

tranquilliser

on

some

this

cases

includes

prescription

is

Effects

the

of

for

for

certain

a

a

anxiety;

Almost

bought

8.7.1).

induces

all

the

10.1

to

drugs

can

counter

find

and

out

why

the

lifetime.

drugs

Effects

functions

over

See

person’s

body

body

lifetime.

drugs

(T able

prescribed

8.7.1

down

relieve

in

and

on

insulin

T able

of

such

physiological,

be

T ype

Others,

heroin

economic

abuse

are

possession

trafficking

•

people.

caffeine, found

alcohol

many

abuse marijuana,

of

for

to

of

Overdose

sleep

be

fatal,

abuse

of

some

sedatives

especially

if

taken

may

with

alcohol

Antidepressant

Prozac,

Relieves

Citalopram

many

for

depression;

other

pain

also

conditions

taken

for

including

relief

Even

the

without

have

severe

untypical

Pain

killer

(analgesics)

Paracetamol,

Relieves

Aspirin,

production

pain

Ibuprofen

cause

by

of

interfering

chemicals

with

that

inflammation

Aspirin

the

Testosterone

Increases

and

athletic

other

anabolic

Diet

pill

muscle

paracetamol

mass

and

performance

steroids

Ephedrine

weight

suppressing

blood

infertility,

the

loss

by

appetite

increasing

metabolic

increasing

use

of

fat

rate

in

Used

and

so

respiration

while

can

of

to

help

become

side

and

as

of

in

to

of

liver

fatal

male

heart

attack,

baldness

a

(e.g.

stimulant,

addictive

effects,

stroke

and

females

concentration

studying);

serious

lead

be

pressure,

hair

such

overdose

can

male

can

behaviour

bleeding

may

than

these

effects,

an

High

attack

126

and

growth

Promotes

side

causes

more

dose,

violent

stomach;

failure

Steroid

taking

prescribed

and

such

it

have

as

heart

STUDY

The

to

is

FOCUS

distinction

country.

banned

Saudi

between

Alcohol,

for

general

Caffeine

is

a

soft

alertness

harm

is

much

legal

and

example,

illegal

is

legal

consumption

in

drugs

in

varies

many

some

from

country

countries

countries,

but

such

as

Arabia.

Non-medicinal

some

for

drugs

stimulant

drinks

and

very

and

present

energy

improving

high,

caffeine

so

are

it

in

beverages,

drinks.

It

stimulates

concentration.

is

regarded

anxiety,

as

insomnia,

such

The

a

the

dose

safe

as

coffee,

CNS,

needed

drug.

The

hallucinations

tea,

increasing

to

effects

and

Figure

cause

of

other

8.7.1

Heroin

addiction

serious

form

of

but

more

is

a

addition,

too far

people

put

severe their

lives

at

risk

from

effects. nicotine

and

alcohol

addiction.

Alcohol

of

is

a

depressant

impulses

along

drug

neurones.

that

At

slows

low

down

the

concentrations

transmission

it

reduces KEY

concentration

and

increases

and

the

our

inhibitions.

time

we

take

to

It

impairs

respond

our

to

sensory

stimuli.

Long

term, 1

alcohol

which

causes

is

Heroin

an

is

a

neurones

The

damage

irreversible

powerful

nerves

and

to

the

liver

causing

that

information

structure

of

heroin

slows

from

is

down

pain

similar

impulses

receptors

to

one

of

to

When

drug

is

any

into

the

skin

which

a

warm

rush

people

of

take

heroin

for

the

first

the

time

body’s

they

in

interferes

brain.

the

as

contentment

and

intense

happiness.

There

are

This

state

who

to

start

but

three

heroin.

impulses

taking

they

heroin

quickly

want

to

become

repeat

the

dependent

feelings

on

the

they

drug

weeks

More

to

the

natural

different

of

Drugs

are

addicted.

painkillers

brain.

But

painkillers.

to

just

and

are

the

The

needed

body

Addicts

deaden

the

economic

dependent

behaviour.

The

swings

and

distant

from

to

crime

body

to

develops

prevent

does

not

nerve

produce

a

have

to

take

heroin

in

in

on

illegal

withdrawal

violent

their

order

family

buy

effects

drugs

of

may

effects

and

Many

crimes

of

They

join

drugs

are

on

cells

more

ever

may

be

to

gain

drug

not

drugs

may

a

cost

provide

to

the

criminal

society

of

facilities

offences,

drugs

to

money

and

is

treat

of

lead

to

apprehending

drug

harm

is

much

very

drug

rehabilitate

traffickers

higher

than

if

abused.

Social

and

economic

effects

greater

drug

abuse

often

normal

are

very

high.

involve

their

sub-culture.

they

are

not

They

able

1

mood

friends,

may

with

drug

abuse;

a

table

8.7.1

alcohol

resort

obtain

women

Make

T able

become

to

to

buy

high.

drug

the

costs

Communities

cope

users.

have

with

and

to

caffeine,

heroin.

an

turn

Explain

the

meanings

of

the

to terms:

But

the

are

illegal

drugs,

to

drug,

dealing

with

legal

medicinal

prescription

drugs

and

drugs.

devoted

social

illegal

drugs,

non-medicinal

drug-related

Resources

suppliers.

of

similar

for

drugs.

addiction,

and

QUESTIONS

social

cost

Discuss

the

social

and

of economic

alcohol

may

its

3 to

which

but

sending

and

The

body

abuse

maintain

lose

drug

because

associated

enough

physiological

the

beneficial,

following prostitution

illegal.

pain.

behaviour.

to

and

tolerance

2 income.

including

non-

legal

have

SUMMARY

People

drug

and

first

of quantities

Social

or

pathogen.

and

4 own

any

is

effects

to

the

own

3

two

to

chemical

euphoria

experienced,

in

a

usually

medicinal;

People

taken

applied

body

with

medicinal

known

or

alters

categories

feel

substance

body

reaction

along

the

2

painkillers.

A

cirrhosis,

condition.

depressant

transferring

molecular

to

POINTS

awareness

drugs,

effects

of

drug

as abuse.

a

greater

proportion

of

the

population

abuse

alcohol.

127

8.8

The

LEARNING

human

Sebaceous

OUTCOMES

skin

gland

Hair

muscle

Hair

At

the

end

of

this

topic

you Sweat

should

be

able

Layer

and

•

describe

the

pore

to:

structure

of

of

stem

cell

melanocytes

the Epidermis

human

skin

Sweat

–

•

describe

the

role

of

melanin

•

describe

the

role

of

the

detect

pain,

pressure,

temperature

skin

in

and

cold

duct

Blood

Sweat

capillar y

gland

heat

control Arteriole

•

define

the

•

discuss

term

the

creams,

use

sun

homeostasis

of

Fat

skin

protection Sensor y

factors

and

layer

skin

neurones

Motor

neurones

bleaching.

Figure

8.8.1

The

skin

–

the

part

between

the

epidermis

and

the

layer

of

fat

is

the

dermis.

The

Blood

gets

Blood

skin

and

its

functions

temperature

Brain

too

hot

falls

The

skin

is

the

largest

organ

in

the

body

and

one

with

important

roles

switches

in on

interactions

between

our

bodies

and

our

surroundings.

The

cooling

functions

mechanisms

Normal

the

body

Normal

• temperature

of

the

structures

labelled

in

Figure

8.8.1

are:

body

Epidermis

–

this

is

made

of

layers

of

squamous

cells

filled

with

temperature

the

tough

fibrous

protein

keratin;

these

cells

provide

mechanical

Brain

protection

switches

on Blood

against

injury

and

are

gradually

rubbed

away.

warming

gets

Blood

temperature

•

Layer

of

stem

cells

–

these

cells

divide

by

mitosis

to

replace

cells

mechanisms too

cold

rises

lost

• Figure

8.8.2

The

control

of

temperature

of

from

surface

Melanocytes

–

of

the

these

epidermis.

cells

are

between

the

stem

cells

and

make

body

is

an

melanin,

example

homeostasis.

its

which

harmful

•

Hair

•

Sweat

glands

pores;

sweat

•

–

provides

Arterioles

the

absorbs

ultraviolet

light

protecting

the

body

from

effect.

–

–

some

insulation

secrete

sweat

evaporates

control

flow

on

the

which

to

lose

of

blood

head

travels

up

sweat

ducts

to

sweat

heat

to

capillaries

which

lose

heat

to

surroundings

LINK •

Homeostasis

is

maintenance

of

conditions

the

in

hypothalamus

is

constant

body.

the

•

Sensory

•

Motor

It

8.4

to

of

see

regulates

homeostasis.

its

neurones

neurones

and

example

see

location

of

10.1

cells

–

detect

changes

in

conduct

nerve

impulses

to

the

CNS

–

conduct

nerve

impulses

to

instruct

the

hair

to

contract

in

for

and

raise

the

hairs

Fat

–

store

of

energy

and

a

thermal

insulator

See

the

control

another

homeostasis.

No

matter

37 °C,

128

sensory

pain

other

T emperature brain

–

and

and

The

• aspects

endings

pressure

body’s muscles

thermostat.

nerve

temperature,

the

near

Sensory

what

unless

the

you

weather

have

a

is

fever.

like,

your

Sensors

in

body

the

temperature

skin

detect

stays

changes

at

in

air

temperature.

detect

If

the

brain

•

changes

Arterioles

The

cooling

When

to

of

the

so

the

glands

heat

of

blood

nerve

the

more

body

spinal

of

the

flowing

impulses

blood

surroundings

produce

the

in

temperature

sends

widen

heat

Sweat

it

Receptors

the

temperature

increases,

loses

•

in

sweat

causes

through

to

the

flows

by

by

cord

the

skin

through

sweat

hypothalamus

promote

the

and

from

to

hypothalamus

to

convection

filtration

the

and

blood.

heat

capillaries

in

the

loss:

and

radiation.

the

blood

evaporate

plasma.

having

a

effect.

we

feel

hypothalamus

cold

and

sends

our

nerve

blood

temperature

impulses

to

the

decreases,

skin

to

reduce

the

heat

loss

by

stimulating:

Figure

•

Arterioles

to

contract

so

reducing

blood

flow

through

8.8.3

The

the

danger

skin

of

using

bleaching

some

products

capillaries.

•

Sweat

If

the

glands

blood

to

stop

producing

temperature

sweat.

continues

to

SUMMARY

fall,

the

hypothalamus

1 stimulates

muscles

heat

to

through

production

contract

the

liver

to

and

in

the

release

liver

heat

muscles

is

by

and

sends

shivering.

warmed

and

impulses

Blood

to

Make

of

the

revision

drawing

a

diagram

showing

before

The

to

receptors

warning

the

effects

changes

in

detect

large,

labelled,

flowing

distributes

heat

to

the

structure

the

the

skin.

diagram

early

by

Annotate

your

body.

Temperature

an

notes

skeletal

of rest

QUESTIONS

in

about

the

skin

possible

blood

temperature

of

adjustments

the

temperature

whether

they

are

are

loss

useful

of

heat

the

to

cold,

the

as

they

give

on

surroundings

in

falls.

made

had

the

by

the

the

body

in

monitored

desired

result

response

by

the

to

2

hypothalamus

(Figure

with

functions

Make

a

and

to

of

the

skin

temperature

sensitivity.

large

diagram

8.8.2).

information

protection,

control

continually

have

in

flow

show

hypothalamus

chart

how

the

controls

body

temperature.

Skin

All

care

people,

whatever

their

skin

colour ,

are

at

risk

of

developing

skin KEY

cancer .

light,

Melanin

which

protection

the

UV

spent

in

is

the

the

causes

against

light.

protection

in

The

skin

cancer .

UV

Creams

light.

higher

afforded.

sun

provides

These

the

sun

between

and

lotions

products

protection

Although

differs

protection

the

actual

people,

it

against

are

available

absorb

factor

length

and/or

(SPF)

of

depends

the

time

on

to

provide

1

deflect

more

able

their

by

to

skin

the

time

of

day

(the

UV

light

is

more

intense

in

the

middle

Body

temperature

monitored

be

the

and

is

controlled

hypothalamus

in

the

brain.

colour 2

and

POINTS

ultraviolet

of

The

skin

protects

the

body

the against

injury

and

is

an

day).

People

in

may

which

wish

areas

particularly

to

of

dark,

lighten

skin

e.g.

their

lighten,

under

skin

they

the

because

have

arms,

or

areas

they

they

of

have

skin

believe

vitiligo

that

that

are

it

or

fashionable

to

have

a

light

in

control;

it

touch,

ingredients

Some

products

European

(Figure

of

contain

Union

8.8.3).

some

as

it

is

skin

bleaching

products

is

have

which

thought

carcinogenic

be

receptors

and

for

temperature.

Skin

care

includes

using

skin.

hydroquinone

to

has

pain

products

The

temperature

is 3

preferable

effector

severe

banned

in

effects.

the

(cancer-causing)

UV

light

cancer;

protect

which

skin

products

with

to

cause

lightening

should

caution

contain

can

against

as

be

used

some

potentially

harmful

substances.

129

Unit

SECTION

1

The

are

8

1:

type

Practice

Multiple-choice

of

cells

that

all

exam

questions

sense

organs

contain

5

called:

A

man

injures

Afterwards,

hand, A

ciliated

B

effector

C

receptor

D

squamous

from

but

Which

all

the

B

all

nerves

of

to

the

following

light

from

a

happen

near

when

the

ciliary

contract

suspensory

all

the

ligaments

tension

and

in

of

the

all

C

relax

the

the

ligaments

of

the

increasing

ligaments

increasing

and

reducing

ligaments

the

a

This

the

tension

and

in

his

his

arm

his

CNS

are

and

the

cut

between

his

hand

and

the

CNS

damaged

Which

part

and

of

the

the

heart

brain

controls

the

breathing

rate?

A

cerebrum

B

cerebellum

C

hypothalamus

D

medulla

the

in

the

suspensory

curvature

of

the

tension

in

oblongata

The

movement

and

decreasing

of

a

tendril

suspensory

the

curvature

of

of

bright

of

is

light

the

an

is

pupil

shone

into

the

eye,

A

an

effector

B

a

growth

C

a

stimulus

D

a

reflex

decreases.

example

B

a

C

homeostasis

D

a

simple

of

heat

at

the

the

is

a

medicinal

A

caffeine

B

heroin

C

nicotine

D

paracetamol

response

following

end

of

a

are

Blood

in

through

skin

responsible

flow

capillaries

the

for

loss

sprint?

Arterioles

the

Which

reflex

voluntary

of

response

the

8

130

receptors

in

increasing

tension

decreasing

accommodation

of

damaged

lens

A

Which

are

that:

cut

lens

diameter

4

be

lens

relax

When

hand

the

are

between

in

nerves

example

3

CNS

his

could

his

away

the

7

D

his

this

touching

hand

lens

reducing

suspensory

curvature

in

between

and

nerves

are

rate

contract

of

his

eyes

6

B

move

cause

accident.

muscles

increasing

curvature

cannot

an

objects

object?

D

A

in

feel

receptors

effectors

The

arm

can

The

A

C

adjust

his

he

he

them.

hand

2

questions

Secretion

of

in

dermis

by

sweat

sweat

glands

A

constrict

decreases

decreases

B

constrict

increases

decreases

C

widen

decreases

increases

D

widen

increases

increases

drug?

around

a

stick

is

an

SECTION

9

2:

Woodlice

not

have

They

Short

are

a

feed

answer

terrestrial

very

on

questions

animals

waterproof

decaying

that

body

wood

do

Relative

Mean

Mean

humidity/%

percentage

of

speed

of

mm min

surface.

and

woodlice/

shelter −1

underneath

stones

and

logs.

Some

woodlice

students

moving/%

investigated

three

the

different

behaviour

1

The

made

moist

cotton

agent

the

on

same

released

wool

the

into

9

a

why

on

on

one

Both

choice

woodlice

both

choice

intensity.

the

minutes,

State

a

other.

light

woodlice

in

10

95

300

25

90

280

50

77

270

75

35

250

100

15

100

investigations.

Investigation

students

of

the

sides

of

side

sides

10

and

woodlice

in

the

intensity

the

a

with

drying

received

chamber.

were

light

chamber

choice

were

After

20

damp

was

e

Draw

the

State

the

c

the

stimulus

behaviour

Suggest

how

woodlice

is

and

shown

the

the

by

chamber.

response

the

behaviour

f

Describe

g

Explain

for

The

made

how

h

(3)

Explain

of

5

chambers

with

these

results.

(3)

the

behaviour

of

how

chambers

more

increases

in

would

find

out

important

of

the

animals

you

to

in

that

woodlice

if

the

made

by

glycerol.

using

20

chamber

of

in

this

The

different

woodlice

and

time,

each

different

left

the

chances

their

use

of

habitat.

three

was

times

placed

minutes.

choice

humidity

or

determining

of

with

the

woodlice

recorded.

This

different

light

the

woodlice.

(4)

25

marks

were

into

At

(4)

different

concentrations

were

5

number

chamber

repeated

for

humidities

in

students

Total humidities.

(6)

results.

the

behaviour

students

show

investigations

out

survival

the

is 2

the

three

carried

(2)

coordinated.

Investigation

to

(1)

woodlice.

of

graph

same

the

b

a

side.

10

of

a

Make

each

the

end

your

moving

groups

diagram

Label

of

the

a

horizontal

following

section

structures

of

on

diagram:

ciliary

was

a

eye.

nerve,

muscle,

retina

cornea,

and

iris,

fovea

lens,

(yellow

optic

spot).

(7)

of b

Explain

how

an

image

is

formed

in

the

woodlice. eye.

Investigation

your

3

c Single

woodlice

were

placed

into

2.

the

The

over

with

d

a

same

speed

humidities

of

each

two-minute

10

as

in

This

use

a

diagram

to

help

Describe

(3)

and

eyesight

explain

of

what

people

is

who

wrong

why

was

was

recorded

repeated

i

short

sight

ii

long

iii

glaucoma

sight

the

speed

of

the

woodlice

(5)

was Total

recorded

from

the

placed

into

after

minutes.

5

the

time

choice

when

they

chamber

table

shows

the

15

marks

were

and

not

(2)

Further results

of

Investigations

practice

questions

2 and

and

with

have:

woodlice.

Explain

The

with

answer.

investigation

woodlouse

period.

may

chambers

the with

You

examples

can

be

found

3. on

the

accompanying

CD.

131

9

Growth

9.1

and

reproduction

Growth

Growth LEARNING

as

At

the

end

should

be

of

this

able

•

define

•

describe

of

a

multicellular

organism

is

a

permanent

increase

in

its

size

OUTCOMES

the

topic

during

structure

of

of

an

growth

which

increase

There

Flowering

growth

of the

result

organism.

you

to:

term

a

is

in

plants

more

in

the

number

about

the

type

of

cells

of

cell

and

the

division

mass

that

of

the

occurs

11.2.

begin

contains

a

their

growth

multicellular

from

embryo

seeds

with

(Figure

stores

9.1.1),

of

each

energy-rich

a compounds

(such

as

starch

and

lipids).

seed

•

describe

during

the

events

that

occur

germination

Radicle

pocket

Radicle Plumule

•

state

in

where

the

growth

bodies

of

occurs

plants

and Micropyle Radicle

mammals

•

discuss

ways

to

measure

growth.

Hilum

Testa

a

b

Figure

9.1.1

Seeds

of

STUDY

FOCUS

Germination

growth

is

the

from

water

by

the

does

of

is

not

seed

until

you

self-sufficient

need

energy.

to

Look

answer

remind

use

at

question

so

its

5.1

yourself

absorb

tissues

of

water

a

external

view,

cotyledons

b

embryo

separated

to

after

show

removal

radicle

and

through

1

help

and

about

the

seed

the

and

micropyle

they

swell.

by

The

osmosis.

testa

or

This

seed

hydrates

coat

and

the

embryo

starts

to

grow:

germination

begins.

it

stores

to

inside

The

following

kidney

beans

events

(Figure

occur

during

germination

of

seeds,

such

as

9.1.2).

5.3 Water

activates

the

enzymes

inside

the

seed

that

catalyse

the

the hydrolysis

properties

bean

with

a

• to

c

process

splits seedling

kidney

coat,

absorption the

of

the

seed

plumule

Seeds of

of

the

c

of

starch

to

maltose,

maltose

to

glucose,

lipids

to

enzymes. glycerol

•

and

Glucose

fatty

and

cotyledons

acids,

amino

to

the

and

acids

growth

proteins

are

to

amino

translocated

points

at

the

in

tips

acids.

the

of

phloem

the

from

radicle

and

the

the

plumule.

•

DID

YOU

Water

activates

increases

There

are

two

flowering

plants

with

groups

plants:

(dicots)

two

have

of

dicotyledonous

have

•

seeds

one

cotyledon.

provide

rates

divide

causing

plants

by

that

the

examples

of

both

Unit.

The

groups

Y ou

only

need

to

the

seeds

of

dicot

as

radicle

rate

of

respiration

cells

with

mitosis.

The

new

pressure

to

and

on

ATP

for

absorb

cells

the

fill

cell

growth

much

with

walls

(see

water

to

5.8).

Seeds

oxygen.

and

stretch

form

them

enlarge.

breaks

through

the

testa

and

begins

growing

into

the

soil

(see

8.2).

The

plumule

breaks

through

the

testa

and

grows

upwards.

Once

know leaves

have

unfurled

and

expanded,

the

plant

can

begin

to

plants and

gradually

becomes

beans. reserves

132

the

respiration

exert

photosynthesise such

the

in

the about

that

There

• this

of

cells

downwards

are

so

have •

with

Cells

to

high

vacuoles

cotyledons;

monocotyledonous

seeds

mitochondria

KNOW?

stored

in

the

cotyledons.

independent

of

the

energy

LINK Cotyledon

First

leaves

Radicle

See

6.8

to

remind

translocation

and

from

to

sources

yourself

about

movement

sinks.

Plumule

KEY

POINTS

Lateral Cotyledon root

1

Radicle

Growth

is

increase

in

mass

an

by

number,

2

Lateral

root

a

permanent

size

or

and

dry

increase

in

cell

or

size,

Germination

involves

activation

tissues

the

seed;

the

seed

of

water

is

swells,

cell

both.

the

inside

absorbed,

the

seed

Radicle

coat

breaks,

then

3

a

a

radicle

plumule

Growth

in

and

emerge.

plants

occurs

by

Radicle

cell

division

apical

tips Figure

9.1.2

Stages

of

germination

of

kidney

bean

in

plants

roots.

are

They

are

cylinders

is

localised

Apical

where

of

growth

tissue

These

meristems

xylem

and

to

tissues

meristems

that

produce

in

of

at

length

extend

new

are

the

cells

unspecialised

the

tips

occurs.

length

that

of

all

cells,

Lateral

meristems

Lateral

of

the

become

are

plants,

such

as

trees

and

shrubs,

which

and

transport

important

keep

year

and

producing

new

woody

tissue

for

roots.

SUMMARY

occurs

regions

at

all

over

stops

at

a

end

certain

of

the

the

body,

long

but

there

bones

(see

are

growing

support.

In

specialised

7.4).

Growth

in

Maize

grains

of

Describe

show

linear

increase,

•

area

•

numerical

•

mass

can

be

e.g.

e.g.

in

in

increase,

measured

in

many

different

reducing

their

Describe,

length

of

surface

e.g.

in

e.g.

using

root

area

of

number

wet

in

would

of

the

best

and

new

indicators

organic

photosynthesis

involves

water.

This

batches

(see

killing

of

compounds

and

the

can

and

a

of

(fresh)

growth

be

6

at

that

absorption

organism

done

harvesting

question

germination.

detail,

leaf

in

kept

the

by

have

dry

in

deep

Explain

in

and

dry

mass,

of

concerned

batch

Unit

been

mineral

dividing

each

end

of

in

some

at

growth

in

full

the

of

sunlight

shade.

the

roles

of

meristems

plants.

leaves

mass

is

how

shoot

mass.

Make

fully

diagrams

since

this

annotated

to

produced

ions.

seeds

a

result

Unfortunately,

order

intervals

as

to

or

remove

all

seedlings

over

the

show

and

the

early

growth

measures

of the

is

sugars

investigate

germination One

you

starch

ways:

4

increase,

to

differences

growth

3

increase,

how

that

mammals

and

•

in

age.

measure

plants

rich

growth

plants

Growth

are

mammals,

you

to

QUESTIONS

year

2

Ways

new

phloem.

tissues

during the

cylinders

in

changed growth

are

produce

and

would after

the

meristems

shoots

the

especially

that

and

starch. perennial

at

shoots;

known

shoots

1 phloem.

are

and

meristems

tissue

xylem

meristems.

roots

plants

of

as

meristems:

meristems

of

lateral

Growth

in

time

kidney

beans.

of

this

the

into

period

5

Suggest

the

advantages

disadvantages

leaves

as

a

of

way

and

counting

to

measure

growth.

9).

133

9.2

Sexual

and

asexual

reproduction

Sexual LEARNING

cells,

At

the

end

should

•

be

define

state

of

this

able

the

asexual

topic

are

you

terms

sexual

differences

In

and

for •

describe

the

structure

of

reproductive

state

the

organs

functions

in

involves

the

two

gametes,

different

much

to

the

reproduction

offspring.

identical

Any

the

form

from

variation

information.

fusion

each

of

male

the

is

variation

is

of

the

due

to

one

as

there

and

and

female

offspring

from

their

parent.

they

is

very

the

nutrients

The

sex

produced

parents.

This

offspring.

only

parent

means

availability

zygote.

other

among

there

to

This

a

inherit

little

effect

and

All

of

water

the

offspring

exactly

variation

the

the

same

amongst

environment,

determine

how

the organisms

grow.

A

group

of

individuals

that

are

all

genetically

systems identical

•

to

example

well human

as

genetically

genetic

the

them

rise

asexual

are

and

between

known

genetically

gives

to:

reproduction

the

reproduction

OUTCOMES

of

is

called

a

clone.

the

systems.

The

The

male

testes

reproductive

are

the

male

system

gonads.

They

produce

the

male

gametes

or

the

male

hormone

Seminal

spermatozoa,

vesicle

or

sperm

for

short,

and

secrete

testosterone.

Prostate

Functions

of

the

organs

labelled

in

Figures

9.2.1–2

are

summarised

in

gland

T able

Sperm

9.2.1.

duct

T able

9.2.1

The

male

reproductive

organs

Urethra

Spongy

tissue

Organ

Function

Testis

•

Penis

Testis

Produces

from

•

sperm

puberty

Secretes

(male

gametes)

throughout

testosterone

the

that

in

rest

huge

of

stimulates

numbers

life

sperm

Foreskin

production

Scrotum

Figure

9.2.1

The

male

development

of

secondary

sexual

characteristics

reproductive

Scrotum

system

and

viewed

from

•

Holds

the

testes

at

a

temperature

slightly

lower

than

the

body

temperature

front

Sperm

•

Transfers

sperm

from

the

testes

to

the

urethra

in

the

Rectum Bone

duct

penis

Prostate

•

gland

Secretes

the

Penis

seminal

fluid

containing

sugars

as

food

for

sperm

•

Inserted

•

Has

into

many

sexual

vagina,

sensory

releases

cells

that

semen

are

that

contains

stimulated

sperm

during

intercourse

Anus

Sperm

STUDY

FOCUS

duct

Humans

Sperm

tubules

in

internal

testis

aspects Figure

9.2.2

The

male

system

134

reproductive

viewed

from

the

side

are

mammals.

fertilisation

of

our

In

and

common

internal

reproduction

as

with

other

development.

you

study

the

mammals

Look

rest

of

for

this

we

have

these

unit.

The

female

reproductive

system LINK

The

structure

of

the

female

reproductive

system

is

shown

in 11.4

Figures

9.2.3–4

and

the

functions

of

the

main

organs

are

the

in

T able

9.2.2.

The

ovaries

are

the

female

gonads,

and

11.5

which

are

offspring

that

make

and

release

gametes

or

eggs,

and

secrete

oestrogen

and

why

sexually

organisms

are

the genetically

hormones

of

the reproducing

organs

explain

summarised

different

from

one

progesterone. another.

T able

9.2.2

The

female

reproductive

organs

KEY Organ

Functions

Ovary

•

1 Produces

and

releases

eggs

(female

POINTS

Eggs

and

sperm

specialised •

Secretes

oestrogen

that

stimulates

development

sexual

Secretes

gametes.

Fusion

progesterone

that

maintains

the

soft

lining

occurs

during

the

second

half

of

the

menstrual

during

•

Moves

eggs

from

ovary

to

uterus

using

cilia

and

Site

of

Sexual

•

Lining

provides

reproduction

site

for

implantation

and

the

genetic

offspring;

of

the

Foetus

develops

•

Muscle

within

the

the

outer

Human

layer

ovaries

contracts

during

of

muscular

and

produce

that

glandular

tissue

at

are

released

at

birth

ovulation Ring

not.

uterus

eggs in

does

embryo

3 •

•

variation

asexual

early reproduction

development

Cervix

in

fertilisation. in

Uterus

not

peristalsis produces

•

but

reproduction.

pregnancy

2 Oviduct

of

sexual

cycle asexual

and

in

of reproduction,

uterus

known

characteristics gametes

•

cells

of as

secondary

are

gametes)

the

base

of

into

the

oviduct

fertilisation

occurs.

the where

uterus The •

Secretes

different

forms

of

mucus

during

the

uterus

is

the

site

of

menstrual internal

development.

cycle

Vagina

•

Retains

•

Lining

contents

secretes

•

Sperm

•

Widens

are

of

uterus

during

4

pregnancy

Human

produce

sperm

released

during

deposited

form

the

in

the

birth

•

Sensitive

are

are

region

at

entry

stimulated

intercourse

vagina

to

vagina

with

many

travel

through

during

sexual

to

the

the

sperm

urethra.

receptors

5 that

that

canal ducts

Clitoris

continually

mucus

to to

testes

The

prostate

gland

produces

intercourse

seminal

fluid.

SUMMARY

QUESTIONS

Oviduct Oviduct

Uterus Rectum

1

Make

a

asexual

table

and

to

compare

sexual

Bone

reproduction.

Ovary

2 Uterus

lining

Make

of Uterus

of

the

labelled

female

and

diagrams

male

wall

reproductive

Clitoris

Cervix

large

Urethra

Annotate

(neck

uterus)

the

Anus

systems.

the

functions

diagrams

of

the

with

organs

Opening Vagina of

that

vagina

3 Figure

9.2.3

The

female

system

front

reproductive

viewed

from

the

Figure

9.2.4

The

you

State

a

have

where

labelled.

the

male

and

female

reproductive

system

viewed

the

from

side

female

b

gametes

where

develop,

fertilisation

and

occurs.

135

9.3

The

The LEARNING

the

end

should

be

monthly

of

this

able

topic

that

define

cycle

•

the

you

cycle.

to:

and

describe

terms

the

the

the

changes

and

role

gland

menstrual

releasing

•

outline

and

•

that

ovary

puberty,

through

the

vagina.

it

that

is

and

the

ready

monthly

girls

breaks

cycle

start

to

down,

to

uterus

are

of

an

changes

have

and

receive

synchronised

periods.

blood

is

embryo

the

This

and

is

cells

if

menstrual

when

are

the

passed

When

menstruation

happens

for

the

first

out

time

shows

the

of

in

pregnancy

her

first

menstrual

cycle

(Figure

9.3.1).

are

born

and

with

they

a

do

very

not

large

number

produce

any

of

potential

more

during

egg

their

cells

in

their

lifetime.

egg

is

surrounded

by

a

small

group

of

cells

and

Each

together

the

of

the

had

form

a

follicle

controlling

Each

by

and

oestrogen

As

month

cells

menstrual

will

At

and

the

to

If

into

of

the

The

If

If

this

and

cycle

This

not

breaks

down

begins

occurs

is

occurs

the

the

If

is

dies

ovary

the

it

to

egg,

protein.

towards

the

pressure

some

Some

is

thick

arrives

and

out

lining

follicle

follicle

cells

occurs,

it

of

the

uterus

and

full

of

nourish

is

in

and

the

protect

uterus

and

implantation.

passes

breaks

passed

moves

meiosis

pregnancy.

embryo

egg

the

by

and

fertilisation

reproduction

the

and

body.

ovulation

of

fat

menstruation,

ovulation.

potential

divides

of

and

releasing

developing,

the

in

after

cell

stores

fluid

throughout

is

stage

occur

This

egg

with

with

bursts

after

with

body

fills

yellow

ovary

week

fertilisation

yellow

the

Each

fills

weeks

it

follicle

vessels

does

then

pregnancy

the

two

oviduct.

the

the

and

that

form

in

lining.

the

uterus

the

develop.

cytoplasm

great

to

In

blood

the

About

so

as

follicles

enlarges

into

time

fertilisation

vagina

it

remain

thicken.

embryo.

sinks

is

ovary

and

as

ovary.

fluid

the

and

two

grows

the

same

glands

the

in

or

size

follicle

the

grow

starts

ovulation

of

the

remain

cycle.

in

follicle

edge

inside

of

one

increases

the

the

effect

on

has

cycle

progesterone

the

girl

uterus

cycle

roles

a

occur

hormones

the

describe

This

uterus

they

the

the

uterus

menstrual

menstrual

the

pituitary

in

the

the

potential

outline

occurs.

During

ovaries,

•

of

ovulation

ovary

during

lining

of

Girls in

the

fertilisation

lining

•

changes

cycle

OUTCOMES so

At

menstrual

out

down.

during

of

The

the

thick

lining

menstruation.

again.

the

embryo

releases

a

hormone

that

stimulates

uterus

the ready

yellow

body

to

remain

active

which

in

turn

of

implantation

the

uterus

nutrients

ensures

There

to

and

that

Control

are

continue

oxygen

as

to

it

menstruation

of

four

the

thicken,

continues

will

not

menstrual

hormones

that

supplying

its

(Figure

9.3.1

During

cycle

the

the

ovaries

and

the

of

•

follicle

•

luteinising

The

menstrual

activities

9.3.2).

ovary

The

stimulating

secretes:

•

oestrogen,

and

•

progesterone.

are

synchronised.

136

the

(LH).

embryo

development.

This

cycle

control

gland

hormone

hormone

the

uterus

pituitary

the

occur.

the

menstrual

menstruation

Figure

stimulates

lining

for

secretes:

(FSH),

and

cycle

with

also

FSH

starts

cells

to

the

Oestrogen

to

cycle

secrete

receive

causes

a

Oestrogen

by

the

fertilised

in

stimulating

oestrogen

the

into

lining

egg

blood

of

and

a

the

follicle

the

uterus

prevents

passes

to

to

develop

and

the

follicle

bloodstream.

the

to

any

thicken

more

pituitary

in

eggs

gland

preparation

developing.

and

prevents KEY

it

making

which

any

more

stimulates

FSH.

Instead

ovulation

and

it

stimulates

the

the

remaining

production

follicle

cells

to

of

form

a 1

yellow

POINTS

LH,

The

menstrual

monthly

The

yellow

thicken

body

even

secretes

more

and

progesterone,

prevents

it

which

breaking

makes

down.

the

Both

uterus

ovary

lining

progesterone

are

needed

to

prepare

the

lining

of

the

uterus

of

the

fertilised

and

The

pregnancy

They

the

the

make

occurs

sure

woman’s

these

that

the

menstrual

the

uterus.

pituitary

and

LH

gland

that

secretes

stimulate

egg. changes

If

is

in

for FSH

implantation

changes

oestrogen 2

and

cycle

body.

two

hormones

lining

cycle

of

the

starting

continue

uterus

stays

to

be

thick

and

they

in

secretion

produced.

the

of

ovary

and

oestrogen

the

and

progesterone.

stop

again. 3

Oestrogen

stimulates

thickening

of

lining

and

gland

to

the

the

the

uterus

pituitary

release

LH.

It

also

LH released;

prevents Ovary

FSH

production.

yellow body

forms

4

LH

stimulates

the

formation

body

the

ovulation

from

of

the

follicle.

the

yellow

remains

The

and

yellow

of

body

Relative

secretes concentration

progesterone

to

Follicle stimulating Luteinising hormone (LH)

maintain

in the blood of

the

uterine

lining.

hormones

from the

pituitary gland

Progesterone

SUMMARY

Oestrogen

QUESTIONS

Relative

concentration in

the blood of

1

Define

the

following

terms:

hormones from

menstruation,

ovulation

and

the ovary

implantation Lining shed

Oestrogen

Progesterone released by yellow

Lining breaks

(menstruation)

released by

body; lining of uterus continues

down if

overay; lining of

to thicken

pregnancy

2

uterus starts

does not

to thicken

occur

Draw

a

time

the

changes

the

ovary

line

to

that

show

occur

in

Lining of

uterus

during

0 days

7 days

14 days

21 days

28 days

3

a

a

and

in

the

menstrual

Name

four

uterus

cycle.

hormones

Time/days

involved

the Figure

9.3.2

Changes

in

secreted

by

the

the

ovary

and

pituitary

uterus

are

coordinated

by

FSH

and

in

coordinating

menstrual

cycle

and

LH

state

gland.

where

they

are

secreted.

b

STUDY

Describe

the

hormones

the The

by

to

menstrual

hormones

show

and

roles

of

these

FOCUS

from

these

charts

to

cycle

involves

the

changes

a

complex

pituitary

and

summarise

all

gland.

make

the

your

series

of

Compare

own

information

events

you

find.

controlling

cycle.

controlled

different

annotated

in

menstrual

ways

diagrams

4

Make

a

human

timeline

gametes

production

until

for

the

from

fertilisation.

137

9.4

Reproduction

birth

Human LEARNING

the

end

of

this

topic

be

able

sperm

mucus

describe

up

to

the

and

are

in

deposited

the

cervix

in

into

the

the

vagina,

uterus

some

and

sperm

then

to

swim

the

through

oviduct.

Many

to: sperm

•

fertilisation

you the

should

control

OUTCOMES

After At

and

events

cells

numbers

leading

do

of

not

survive

sperm

to

this

difficult

increase

the

journey.

chances

of

A

man

produces

huge

success.

including If

there

is

an

egg

in

the

oviduct,

a

sperm

cell

may

succeed

in

fertilisation fertilising

•

describe

the

process

it.

First

enzymes

are

released

by

the

tip

of

the

sperm

to

of digest

a

pathway

through

the

jelly

coat

around

the

egg.

implantation

The •

describe

the

functions

egg the

amnion,

placenta

discuss

of

sperm

membrane

the

advantages

the

sperm

nucleus

fuses

enters

the

with

egg

the

membrane

cytoplasm

around

(Figure

the

9.4.1).

immediately

forms

around

the

fertilised

egg

or

zygote

stop

disadvantages

of

other

sperm

cells

from

entering.

Only

one

sperm

is

successful.

and The

methods

two

nuclei

fuse

together

to

form

the

zygote

nucleus.

Sperm

can

of stay

birth

the

cord to

•

membrane

and

and A

umbilical

cell

of

alive

for

two

or

three

days,

so

if

intercourse

happens

just

before

control. ovulation

the

sperm

can

fertilise

an

egg,

if

it

is

released

during

this

time.

Implantation

After

fertilisation

embryo.

Head

of

one

penetrates

sperm

egg

is

a

is

moved

Egg

to

fuses

may

of

cilia

zygote

cells,

on

several

divides

which

the

by

dividing.

moves

epithelial

similar

to

Tail

embeds

the

vessels,

which

along

peristalsis

oviduct.

the

in

a

oviduct

the

two-celled

the

embryo

The

embryo

and

also

by

gut.

days

into

for

the

the

soft

embryo

lining

of

to

the

reach

the

uterus.

uterus.

This

is

The

The

uterus

lining

is

thick

with

many

called

glands

provide

Carbon

dioxide

food

and

oxygen

to

the

embryo

by

and

blood

diffusion.

egg

embryo

T able

as

a

has

and

chemical

developed

foetus

(Figure

wastes

organs

diffuse

and

is

out

of

the

recognisably

embryo.

human,

it

Once

is

9.4.2).

9.4.1

9.4.1

shows

the

functions

of

the

structures

labelled

in

sperm

Figure

9.4.2.

Fertilisation

T able

Organ

Structure

Amnion

•

Thin

9.4.1

How

the

foetus

develops

Function

layer

of

cells

and

fibrous

tissue

•

Encloses

foetus

amniotic

against

•

Disc

of

large

138

the

form

hours,

of

successful

cord

down

cells

to

few

sperm

known

Umbilical

a

with

the

Placenta

mitosis

After

stop

implantation.

entering

Figure

the

continues

contractions,

take

embryo

membrane

successful other

sperm

ball

by

muscular

changes of

hollow

it

membrane

It

Nucleus

Then

•

tissue

surface

Rubbery

two

that

cord,

veins

has

many

villi

giving

a

•

area

containing

an

artery

and

a

of

and

watery

which

mechanical

Exchange

blood

in

fluid,

substances

Deoxygenated

•

Oxygenated

the

protection

between

foetal

blood

blood

blood

–

damage

maternal

•

fl uid

provides

flows

returns

to

to

the

the

placenta

foetus

Birth

Birth

control

control

involves

any

methods

removing

Methods

the

that

conception

has

is

started

method

to

that

prevent

embryo

or

prevent

and

to

Umbilical

prevents

fertilisation

foetus

at

fertilisation

implantation

develop,

then

some

are

have

the

the

or

birth

of

a

baby.

implantation

stage

during

methods

occurred

of

and

destruction

of

this

This

pregnancy.

embryo

is

Placenta

occurring,

contraception.

the

cord

an

or

If

foetus

abortion. Amniotic

Abortion

is

birth

control

but

not

a

method

of

contraception. fluid

Amnion T able

T ype

9.4.2

Methods

of

birth

of

birth

control

Details

Advantages

Disadvantages

control

Figure

9.4.2

A

Barrier:

prevents

condom

fits

over

sperm

the

reaching

penis

the

egg

in

the

oviduct

protects

can

against

during

KEY

foetus

in

the

prevent

release

POINTS

split 1

to

Male

fuse of

semen

into

transmission

of

fits

over

cervix

to

form

the

woman

is

does

cervical

prevent

After

entry

of

in

control

protect

into

uterus

contains

(the

oestrogen

a

zygote.

fertilisation

by

ball

of

cells

very

low

not

all

can

use

embryo.

and/

failure

rate

progesterone

follicles

some

in

of

the

and

duct

tied;

are

ovary

is

is

called

foetus.

at

risk

of

3

The

developing

cut

no

prevents

other

form

do

of

the

connected

clots

not

amnion

protect

by sperm

embryo

and

women

blood

Surgical:

the

organs

method;

prevents

development

as

further

this

a –

zygote

form

women

develops or

to

known

After

development, pill)

the

mitosis

STIs

an Hormonal

gametes

fertilisation

against

a sperm

at

not

divides

cap

female

STIs

2 diaphragm

and

together

intercourse to

vagina

and

full-term

uterus

method

the

holds

fluid

foetus,

to

the

umbilical

to

which

is

placenta

cord.

protect

against

STIs;

4

The

placenta

is

the

site

of

vasectomy sperm

being

ejaculated

sterilisation

oviduct

is

cut

contraception

these

is

permanent

between

methods

foetal

necessary

prevents

reaching

site

exchange

of

of

substances

maternal

blood

and

blood.

and

birth tied;

are

control

eggs

of

SUMMARY

QUESTIONS

fertilisation

Natural

monitoring

body

temperature

changes

mucus

fertile

in

to

no

or

menstrual

higher

involved;

cervical

need

determine

time

costs

to

no

rate

obtain

failure

than

1

2

condoms,

during

pills,

etc.

zygote

cycle

have

used

birth

control

and

methods

for

centuries.

The

the

contraceptive

pill

in

the

1960s

gave

women

far

their

fertility

children

to

and

gave

have

and

greater

when.

opportunities

Widespread

more

for

people

provision

Describe

allowed

governments

to

take

steps

to

limit

of

population

countries

birth

control

methods

have

been

so

have

fallen

below

the

level

needed

to

maintain

to

plan

growth.

successful

the

embryo;

sperm;

embryo

roles

sac,

of

the

placenta

and

cord.

how

Explain

the

biological

contraception

that

involved

in

each

of

In

methods

of

birth

control

birth

in rates

the

and

control

the some

between

ovum

the

principles has

implantation.

development

4 many

at

at

foetus.

umbilical

over

and

and

amniotic

of

happens

Distinguish

following:

3

People

what

fertilisation

other

methods

State

T able

9.4.2.

population.

139

9.5

Flowers

Flowering LEARNING

Flowering At

the

end

of

this

topic

be

able

outline

the

flowering

including

stages

plant

grains

reproduction

pollination

structure

male

of

flower

•

compare

insect-

function

the

and

seed

by

vegetative

growth

by

growth;

at

producing

some

flowers

of

to

the

gamete

grows

the

male

female

to

into

the

an

plants

have

stamens

of

gamete,

part

of

female

embryo

the

see

T able

for

with

flowers

flower

gamete

that

flowers

the

9.5.1.

where

inside

male

pollen

These

they

internal

develops

both

produce

will

are

deliver

fertilisation.

the

ovule

The

which

an

each

structures

contain

Most

The

the

seed.

The

embryo

remains

dormant

inside

the

seed

and

while the

from

reproductive

structures.

that

becomes insect-pollinated

state

grow

begin

reproduction.

transferred

and

the

the

will

female

zygote describe

plants

they

sexual

and

in

fertilisation

•

cycle

to: for

•

life

you stage

should

plant

OUTCOMES

it

is

dispersed

away

from

the

female

parent

plant.

part

The

of

transfer

agents

wind-pollinated

of

flowers.

of

flowers

by

of

pollen

pollination

shows

from

are

how

the

anthers

insects

they

are

and

to

the

adapted

stigma

wind.

for

is

pollination.

Studying

pollination

the

by

T wo

structure

insects

and

wind.

Insect-pollinated

flowers

Anther

These

flowers

are

often

large

and

conspicuous

to

insects,

which

are

Style

attracted

pollen

by

bright

(Figures

colours,

9.5.1–4).

scent

Nectar

is

and

a

the

prospect

liquid

rich

in

of

nectar

sucrose,

and

and

pollen

Petal

is

a

good

The

functions

flowers

Filament

Ovary

ovules

9.5.1

This

drawing

made

of

by

has

vitae

of

protein.

the

different

summarised

9.5.1

Functions

of

in

a

Sepal

Protects

the

Petal

Attracts

insects

the

having

part

Anther

of

flower)

Carpel

(female

of

when

the

–

the

Filament

Style

flower)

tubes

–

–

140

by

insect-pollinated

in

insect-pollinated

flowers

they

being

supports

and

pollen

is

bud

brightly

that

nectar

grains;

coloured,

direct

at

the

anthers

the

centre)

split

ripe

anther

through

and

provides

xylem

and

phloem

deposited

sugars

for

Ovary

–

contains

ovules

Ovule

–

contains

the

equivalent

of

are

the

sugars

a

(lines

pollen

grains

is

large,

source

produces

–

it

of

growth

which

embryo

the

the

develop

sac

pollen

of

which

pollen

into

is

–

are

insects.

an

sac

–

contains

the

grain

female

seeds

the

vitae

coloured

that

pollinated

when

guides

the

provides

Embryo

indicator

by

honey

pollen

ions

Stigma

part

female

Lignum

brightly

these

structures

flower

towards

water,

are

different

Function

(male

of

the

Structure

Stamen

Flowers

in

9.5.1.

flower

half.

insect

9.5.2

structures

T able

been

and

Figure

in

inside

sectioning

Lignum

are

of

with

T able

Figure

source

gamete

Wind-pollinated

These

flowers

are

insect-pollinated

individual

grows

This

is

to

into

the

lightly

their

much

so

to

rest

the

can

be

the

Stigmas

They

and

are

grouped

the

that

it

attached

pollen.

are

above

ensure

air,

smaller

flowers.

flowers

which

flowers

closely

of

the

pollen

spread

is

large

conspicuous

green

and

so

and

in

together

plant

away

wide.

they

Inflorescence

an

from

to

Single

in

and

the

the

trap

those

Often

of

the

inflorescence,

9.5.5

Anthers

shake

feathery

than

colour.

in

(Figures

blown

far

filaments

are

less

often

9.5.6).

plant

are

and

large

wind

pollen

to

and

release

grains.

spikelet

Single Spikelet Figure

9.5.3

A

half

flower

drawing

flower (group

of of

a

flower

of

Pride

of

flowers) Barbados.

to

identify

Use

the

Figure

9.5.1

parts.

Anther Stamen

Filament

Inside

a

single

flower

Feathery

stigma

Long

filament

Style Anther

with

mobile

hinge Ovary Figure

9.5.4

Flowers

of

Barbados

Figure

9.5.5

A

wind-pollinated

Pride

are

of

typical

of

the

flower legume

family

of

flowering

plants.

KEY

POINTS

1

Pollination

2

The

is

the

structure

of

transfer

flowers

insect-pollinated

that

make

small,

pollen

and

SUMMARY

1

Define

2

Draw

and

flowers

feathery

related

have

scent;

that

pollen

to

large,

anthers

the

agent

brightly

to

large

trap

anthers

pollen

to

of

stigma.

pollination:

coloured

wind-pollinated

have

stigmas

from

flowers

to

in

flowers

have

produce

the

DID

YOU

Lignum

for

the

lasted

KNOW?

vitae

locks

for

wood

on

over

a

was

Lake

100

used

Erie.

They

years.

much

wind.

QUESTIONS

vegetative

a

is

flowers

nectar

green

of

flow

growth,

chart

reproductive

diagram

to

show

growth

the

life

and

cycle

pollination

of

flowering

plants.

3

4

a

Make

b

Label

Make

a

a

half

the

table

flower

parts

to

and

drawing

of

annotate

compare

wind-

an

with

and

insect-pollinated

the

flower.

functions.

insect-pollinated

flowers. Figure

9.5.6

141

9.6

Pollination

to

seed

dispersal

Self-pollination LEARNING

In At

the

end

of

this

topic

be

the

able

examples

one

flower

in

to

this

the

compare

self-

and

from

cross-

which

where describe

occurs

how

in

describe

develop

ovaries

describe

is

another

transferred

flower

on

from

the

another

anthers

plant.

This

is

how

from

seeds

and

any

does

not

pollen

then

lead

lands

on

the

stigma

self-pollination

to

happens

fertilisation,

all

the

time

but

and

of

occurs.

there

it

the

In

are

leads

same

most

to

flower

plants

some

plants

fertilisation.

ovules

FOCUS

fruit

Remember

and

sequence

fertilisation

how

If

released

plants

that

of

pollination, •

pollen

of

fertilisation

flowering

after

is

self-pollination

STUDY

•

it

self-pollination

pollination

•

section,

stigma

to: cross-pollination.

•

cross-pollination

you of

should

and

OUTCOMES

seeds

pollination

events

(3)

is

(1)

growth

comes

pollen

of

before

released

pollen

tube,

fertilisation.

from

and

The

anthers,

(4)

(2)

fertilisation.

Use

are

this

sequence

for

the

basis

of

your

revision

notes

for

this

topic.

dispersed.

Fertilisation

Fertilisation

land

to

female

If

a

the

a

pollen

pollen

As

it

the

to

grain

tip

enter

Events

Pollen

dispersed

into

from

a

gains

the

the

ovule

with

breaks

and

a

it.

–

the

with

zygote

is

of

it

small

allow

the

the

same

to

the

by

when

now

the

at

the

male

of

it

occur .

produces

(Figure

and

ovary,

entry

tube

the

ovule.

nucleus

nucleus.

the

9.6.2).

carries

the

to

gamete

gamete

fusion

can

style

the

pollen

transferred

species,

ovary

reaches

female

formed

of

hole

the

is

fertilisation

tissues

When

to

complete

nucleus

that

style

the

the

down

fuse

so

stigma

from

micropyle

which

after

ripe

is

male

ovule

down

nutrition

nucleus

the

tube

in

a

grows

the

The

two

This

is

nuclei.

fertilisation

the

The wind

it

on

Pollination

stigma.

inside

lands

gamete

of

pollination.

female

which

through

fertilisation

9.6.1

the

gamete

tube

male

The

on

grows,

grows

Figure

follows

grains

zygote

divides

by

mitosis

and

grows

into

the

embryo.

The

ovule

pendulous

forms

the

seed

with

the

embryo

inside

it.

After

fertilisation,

many

of

sedge

the

parts

and Stigma

of

the

stamens

flower

wither

are

and

not

fall

needed

off.

They

any

have

more,

so

the

completed

sepals,

their

petals

functions.

Germinating

pollen

The

grain

ovary

part Pollen

tube

grows

down

of

swells

the

provide

to

ovary

water

form

is

and

the

the

fruit

placenta

nutrients

to

with

that

the

seeds

inside

contains

growing

it.

xylem

seeds.

The

central

and

phloem

to

Fruits

develop

in

style

ways

have

Ovule

that

one

contain

Seed

Male

gamete

nucleus

about

Pollen

to

tube

with

egg

cell

9.6.2

nucleus

few

to

the

seeds

seeds

and

dispersal

and

split

are

of

their

dispersed

open

to

seeds.

Some

together.

release

Other

fruits

only

fruits

them.

dispersal

Fertilisation

over

plants

a

have

wide

mechanisms

area.

This

avoids

for

shedding

competition

and

with

dispersing

the

parent

their

plant

micropyle

in

a

between

the

seedlings.

The

disadvantages

are

that

many

flower

will

142

a

many

Flowering

and

Figure

or

related

penetrates

seeds fuse

are

be

eaten,

or

land

somewhere

not

suitable

for

growth.

seeds

T ypes

of

seed

and

fruit

dispersal KEY

1

Wind

POINTS

Cross-pollination

transfer

The

fruits

develop

hairs

of

that

catch

the

wind

the

seeds

to

travel

of

one

flower

the

to

and the

allow

the

from

or anthers

wings

is

pollen

stigma

of

a

flower

on

a

some different

plant

of

the

same

distance.

Figure

9.6.5

A

howler

willing

seed

monkey

dispersal

forest

is

participant

for

a

species;

self-pollination

transfer

of

same

this

2

tree.

Pollen

the

tubes

style

This

fruit

Amazon

of

the

vine

dry

each

deliver

gamete

give

a

has

with

quite

two

a

wing

structure

helicopter

it

falls

that

from

and

split

open,

suddenly,

to

project

within

the

seeds

away

from

the

A

zygote

like

spins

the

is

produced

carry

to

the

them

fur

of

some

or

to

form

a

multicellular

After

fertilisation

embryo.

the

seed,

into

parts

the

a

ovule

the

fruit,

wither

ovary

all

and

other

die.

that

mammals

distance

shaking

at

divides

as

that

5

before

them

Seeds

are

dispersed

competition Figure

rubbing

this

tree.

flower

attach

ovule.

a

develops

hooks

female

embryo

plant.

becomes

have

the

their

Animal

fruits

the

the

often

4

Some

to

inside

fertilisation; to

down

Monarch

3

seeds

to

grow

(self-dispersal)

sac Fruits 9.6.3

the

the

flower.

gamete

Figure

is

within

in

male

Mechanical

pollen

9.6.6

Fruits

of

legumes

crack

halves,

eject

open

which

the

to

to

avoid

colonise

dry

off. and

and

into

twist

new

two

areas;

occurs

to

seeds.

by

by

seed

wind,

dispersal

water

and

animals.

Water

Some

rivers

plants

and

buoyant

Figure

9.6.4

Duppy

sharp

fur

needles

hooks

and

to

often

have

that

stick

to

from

the

fruits

withstand

These

that

by

are

that

immersion

parent

of

along

produce

SUMMARY

in

by

water.

water

miles

1

–

Describe

and

fruits

often

attract

are

full

brightly

away

animals,

of

such

2

Describe

ovule

to

birds,

to

eat

them.

to

the

the

and

changes

female

ovary

fertilisation

until

are

either

from

seed

dispersal.

List

the

advantages

and

The disadvantages

seeds

that

gamete,

monkeys 3

and

and

plant.

sugars

as

happens

pollination

fertilisation.

clothing.

coloured

what

between

occur

Fleshy

QUESTIONS

can

dispersed

thousands

the

grow

sea

scattered

on

of

seed

the dispersal.

ground

or

eaten

and

egested

far

Figure

from

the

parent

9.6.7

Fruits

of

manchineel

can

4

plants. be

dispersed

by

Suggest

the

advantages

of

ocean

seeds

being

dispersed

by

currents.

animals

DID

YOU

KNOW?

5

Make

that

revision

comparing T rees

release

huge

numbers

of

seeds

during

their

lifetime.

ingest

of

those

seeds

needs

to

germinate

and

grow

for

its

and

Only

successfully

as

in

flowering

a

plants replacement

notes

fertilisation

development one

them.

and

humans.

parent.

143

Unit

SECTION

1

The

A

9

1:

best

a

Practice

Multiple-choice

definition

permanent

an

organism

an

increase

of

increase

in

SECTION

questions

growth

6

is

the

exam

dry

mass

Some

in

the

size

of

an

students

early

400

seeds

an

increase

in

the

number

answer

questions

investigated

growth

of

maize

the

germination

plants.

They

took

of

40.

and

The

divided

seeds

were

them

into

soaked

in

10

batches

water

and

organism planted

C

Short

and

of B

2:

questions

of

cells

of

in

seed

compost.

an

At

intervals

of

time

a

batch

was

removed

from

organism

the D

an

increase

in

the

volume

of

an

compost,

Which

are

the

features

of

wind-pollinated

plant

flowers?

A

T able

anthers

are

inside

flowers,

smooth

weighed.

was

thoroughly

and

The

mean

calculated.

dry

The

mass

results

of

are

each

in

T able

1.

1

pollen, Stage

no

dried

organism then

2

washed,

of

Day

Mean

dry

Presence

scent growth

B

coloured

C

large

petals,

flowers,

sticky

pollen,

nectaries

strong

present,

mass/g

scent

per

of

leaves

plant

light Germination

0

0.40

✗

1

0.33

✗

15

0.29

✗

30

0.64

✓

50

4.65

✓

64

20.01

✓

71

34.56

✓

100

111.65

✓

113

121.99

✓

pollen

D

no

petals,

anthers

are

outside

flowers,

no

nectaries

Early 3

What

is

the

function

of

the

ovary

in

growth

human of

seedling

reproduction?

A

4

formation

of

a

mature

B

secretion

of

FSH

C

secretion

of

LH

D

site

What

of

is

ovum

(egg)

Vegetative

growth

fertilisation

cut

during

a

vasectomy?

a A

Explain

why

B

sperm

C

ureter

dry

mass

of

i

Describe

plants

Which

are

A

features

dispersed

light

are

by

seeds

associated

with

seeds

as

animals?

with

fruits

c

that

are

formed

fleshy

Explain

the

that

into

the

(2)

the

growth

shown

in

of

the

the

maize

table.

(3)

C

fruits

D

large

the

changes

in

dry

masses

of

plants.

(4)

State

two

disadvantages

mass

as

way

a

of

of

using

recording

the

dry

growth

fruits

that

are

brightly

coloured

d

Figure

that

dry

seeds

to

that

open

float

of

(2)

1

shows

cucumber

leaf

the

change

over

20

in

area

of

a

days.

explosively

on

water

Suggest

i

how

you

growth

ii

the

a

would

in

of

obtain

surface

advantages

way

plants,

144

determined

plants.

plants.

wings

B

students

maize

urethra ii

5

the

duct

b

D

the

oviduct

of

area

using

measuring

such

as

results

of

a

leaf

growth

cucumbers.

for

the

leaf

area

of

(3)

as

crop

(3)

7

240

a

220

Describe

how

pollinated

the

flower

structure

differs

of

an

from

insect-

the

structure

200

of

a

wind-

pollinated

flower.

(5)

180 2

mc/fael

160

b

i

State

the

difference

between

cross-

140

pollination

and

self-pollination.

(2)

fo

120

aerA

100

ii

Explain

how

plants

ensure

that

their

80

flowers

are

cross-pollinated

and

not

60

self-pollinated.

40

(3)

20

c

Describe

what

happens

following

pollination

0

2

0

4

6

8

10

Time

12

da

14

16

18

to

20

ensure

that

an

embryo

is

formed.

Total Figure

15

marks

1

8 The

(5)

s

ovaries

of

tomato

flowers

develop

a

Describe

and fleshy

fruits

after

fertilisation.

Figure

2

shows

section

through

a

tomato

roles

umbilical

of

cord

the

in

placenta,

the

amnion

development

of

a a

vertical

the

into

foetus.

(6)

fruit.

b

Condoms

are

used

for

birth

control.

Sepal

i Seeds

What

name

is

used

to

describe

this

Placenta

method

ii

Explain

of

how

method

Fruit

birth

of

a

control?

condom

birth

(1)

acts

as

a

control.

(2)

wall

iii

State

an

added

advantage

of

using

condoms.

Figure

c

e

(1)

2

The

the

placenta

growth

i

a

sugar

ii

the

of

the

tissue

is

that

the

source

Measurements

the

that

through

iii

provides

sugars

seeds.

to

support

control.

Name

transported

transports

Vasectomy

is

another

Explain

during

of

the

the

these

seeds

sugars

from

growth

as

d

Outline

three

social

many

of

shown

Mean

early

width

Placenta

Pericarp

Fruit

in

width

width

diameter

Explain

in

marks

T able

practice

questions

2. examples

the

can

be

found

accompanying

CD.

size/mm

of

fruit

mid

development

late

the

the

ripe

0.2

0.5

1.0

1.1

15.0

21.6

12.2

5.0

2.6

8.1

10.2

12.2

27.0

42.6

79.2

139.2

(OCR

f

15

fruits Stage

Seed

(3)

tomato

on

tomato

of

(3)

2

Features

aspects

contraception.

and

T able

birth

(2)

Total

sugars.

taken

of

prevents

placenta

were

their

method

this

pregnancy.

to

Further

fruits

how

reasons

for

the

March

changes

1999)

shown

table.

(5)

Total

25

marks

145

10

Disease

10.1

Diseases

Disease LEARNING

a

At

the

end

should

be

is

not

an

of

this

able

•

define

•

distinguish

the

topic

or

symptoms

you

help

to:

term

condition

to

illness

to

word

to

define;

decide

which

There

physiological

way

diseases

the

of

treatment

these

are

is

gives

control

the

it

can

be

defi ned

body.

We

can

as

they

look

for

professionals;

disease

we

describe

certain

signs

that

have.

disease

deficiency,

and

discuss

affects

of

disease

between

pathogenic,

hereditary

that

medical

Categories

•

easy

OUTCOMES

to

many

ways

classify

examples

to

them

of

the

classify

by

diseases

cause

four

as

into

shown

categories

of

in

different

T able

disease

categories.

10.1.1.

that

you

The

One

table

should

know.

and

T able

diseases.

10.1.1

Category

Examples

and

of

causes

of

disease

Examples

Cause

Pathogenic

HIV ,

Virus

(see

yellow

cause

10.2):

influenza,

fever

disease-causing Tetanus,

organisms

tuberculosis

Bacterium

or (TB),

gonorrhoea

pathogens Ringworm,

Deficiency:

Night

lack

total

of

a

nutrient

(see

in

thrush

Fungus

blindness,

Lack

of

vitamin

A

Scurvy

Lack

of

vitamin

C

(Iron-deficiency)

Lack

of

iron

blindness

diet

5.7)

anaemia

Hereditary:

inheritance

Figure

10.1.1

Is

poverty

World

a

Health

(WHO)

children

at

risk

of

The

mutant

a

Mutant

cell

anaemia

(see

11.6)

allele

of

gene

for

of

gene

for

haemoglobin

allele Haemophilia

Mutant

(see

blood

allele

Organisation

certainly

as

and

disease?

Sickle

of

like

many

deficiency

thinks

these

11.7)

clotting

factor

so,

are

pathogenic

Physiological:

malfunction

Inability

Diabetes

or

of

of

to

produce

tissues

to

insulin

respond

to

it

diseases.

organs

or

organ Cause

Hypertension

(in

most

cases)

systems unknown STUDY

The

FOCUS

number

some

of

cases

hereditary

decreased.

of

diseases

Genetic

Treatment

has

(DNA)

given

whether

or

to

This

for

parents

to

have

have

the

involves

inherited

proceeding

choice

children

assisted

the

conditions

with

at

all

•

diseases

embryos

antibiotics,

infections;

•

before

such

they

as

are

anti-viral

drugs,

retroviral

drugs

anti-fungal

11.6). ringworm.

146

disease

are

treated

with

drugs:

penicillin

not

such

for

and

suitable

as

amoxicillin,

for

acyclovir

treating

HIV

treating

for

(see

are

viral

treating

used

and

to

treat

fungal

herpes

and

bacterial

diseases

anti-

10.3)

pregnancy •

(see

of

of

reproduction.

testing

control

testing Pathogenic

has

and

drugs,

such

as

clotrimazole

for

treating

thrush

and

Vaccination

is

an

effective

control

measure

for

many

infectious STUDY

diseases.

polio

It

from

providing

are

has

been

the

western

dietary

treated

in

used

to

eradicate

hemisphere.

supplements.

different

ways

smallpox

Deficiency

Hereditary

depending

the

diseases

and

on

from

world

are

treated

physiological

the

cause

and

by

diseases

its

FOCUS

and

effect.

The

control

another

of

blood

example

Remember

that

concentration The

concentration

of

glucose

in

the

blood

is

maintained

limits.

Tissues

in

the

pancreas

detect

changes

in

within

This

increases

when

you

absorb

a

meal

and

between

meals

and

when

you

exercise.

The

tissues

in

the

at

the

hormone

insulin

when

the

concentration

increases.

to

the

cells

in

storage

the

liver

and

decreases,

to

break

body

muscles

muscles

mellitus

stop

make

produced

Diabetes

diet

high

I

to

usually

II

this

in

in

the

If

absorb

the

glucose

and

glucagon,

concentration

which

often

to

a

coma

of

stimulates

do

the

not

have

storage

insulin

of

convert

as

glycogen.

glucose

liver

cells

just

called

or

the

diabetes)

target

cells

occurs

in

the

when

liver

and

it.

starts

in

childhood

pancreas

usually

form

of

starts

are

later

diabetes

and

refined

pressure

and

high

often

or

adolescence.

destroyed,

so

The

no

cells

insulin

is

if

sugar

in

life.

there

and

is

not

There

is

genetic

a

very

high

risk

predisposition,

enough

fi bre.

Obesity,

of

a

high

Figure

10.1.2

physical

blood

cholesterol

concentration

developing

this

are

increase

the

risk

of

Exercise

health

by

benefits

reducing

diseases

and

the

people’s

chances

often

of

improves

also

their

that

diabetes

into

glucose.

insulin

fat

factors

going

they

stimulate

physiological

blood

untreated

of

all.

type

developing

(most

responding

insulin

at

to

producing

type

glycogen.

secretes

glycogen

stops

Diabetes

that

pancreas

down

Diabetes

the

the

compound

but

limits.

Insulin

glucose it

fluctuates

pancreas

to stimulates

glucose

narrow

with

risk

because secrete

the

decreases

are in

is

the

People concentration.

glucose

homeostasis.

within

stays narrow

of

mental

health

as

they

feel

better

about

disease.

themselves.

Insulin

at

is

used

regular

that

it

is

to

treat

intervals

not

to

excreted

diabetes;

stimulate

in

the

this

the

has

to

be

storage

of

injected

glucose

into

as

the

blood

glycogen

so

KEY

1

People

with

hypertension

have

high

blood

pressure

and

are

Disease

best

of

the

fact

indicators

as

there

that

a

are

few,

person

is

if

at

any,

risk

symptoms.

of

heart

It

is

disease

one

or

that

drugs

reduce

and

blood

The

roles

are

the

prescribed

effect

of

for

stress

hypertension,

hormones

that

including

increase

beta

the

defined

illness

as

that

of the

body.

their

People

can

symptoms;

blockers

heart

medical

staff

can

signs

help

their

observe

rate to

diagnosis.

pressure.

2

of

diet

and

exercise

Four

are

categories

than

pay

for

expensive

drugs,

it

is

better

to

of

pathogenic,

hereditary Rather

or

stroke. describe

Various

be

condition

affects

the

can

often a

unaware

POINTS

urine.

and

disease

deficiency,

physiological

prevent diseases.

physiological

balanced

in

diseases

diet,

moderation

developing

taking

(if

at

many

of

developing

exercise,

all)

are

these

in

not

the

first

smoking,

simple

ways

in

place.

and

which

Eating

drinking

people

a

alcohol

can

3

avoid

Drugs,

are

diseases.

such

used

to

diseases;

as

people

physiological A

balanced

diet

provides

all

the

nutrients

needed

for

good

health

prevention

of

deficiency

diseases.

It

also

means

that

people

do

more

energy

in

their

diet

than

they

expend

in

daily

activities.

the

risk

of

storing

excess

fat

and

becoming

overweight

or

to

take

for

for

their

The

risks

reduced

Explain

how

diseases

are

Discuss

as

–

whole

lives.

of

developing

the

ways

in

by

diseases

taking

can

be

exercise

categorised. and

2

such

longer

QUESTIONS physiological

1

drugs,

much

obese.

4

SUMMARY

often

This often

reduces

diseases

not insulin,

have

pathogenic

with

and need

the

antibiotics,

treat

which

diseases

can

be

prevented.

eating

a

throughout

balanced

diet

life.

147

10.2

Mosquitoes

This LEARNING

section

serious

At

the

end

should

•

be

identify

of

this

able

the

the

topic

life

their

•

Aedes

aegypti

different

describe

types

of

mosquito

that

transmit

three

•

Anopheles

which

transmits

dengue

and

yellow

fever

cycle

of

which

transmits

malaria.

stages species

have

the

same

life

cycle.

Female

Anopheles

mosquitoes

mosquitoes their

eggs

in

bodies

of

still

water ,

such

as

ponds,

drainage

and

habitats irrigation

•

two

diseases:

you

lay and

about

tropical

to:

These in

is

OUTCOMES

their

life

the

water

storage

tanks,

in

fact

anywhere

that

fills

with

cycle water .

explaining

channels,

term

Female

Aedes

lay

eggs

that

withstand

dry

conditions

and

deposit

complete them

on

the

sides

of

containers

of

water

where

they

may

survive

for

metamorphosis months

•

define

the

term

vector

until

the

container

fills

with

water .

of The

eggs

of

both

types

of

mosquito

hatch

to

form

larvae,

which

live

disease in

•

describe

the

role

water

in

of

dengue

fever

angle

state

on

bacteria

and

small

organisms.

Aedes

to

the

have

breathing

surface;

tubes

Anopheles

at

their

larvae

rear

rest

end

parallel

and

to

rest

the

at

surface

out

gas

exchange

through

their

whole

body

surface.

fever

After •

feeding

and carrying

yellow

surface,

transmitting an

malaria,

the

of Larvae

mosquitoes

near

the

ways

mosquitoes

moulting

several

times,

each

larva

changes

into

a

pupa.

During

are the

pupal

stage

the

body

goes

through

a

change

into

an

adult

with

controlled a

•

discuss

the

impact

on

very

different

adults

populations

of

diseases

plants

and

emerge

from

sexes

need

feed

the

to

on

Female

she

using

take

parasite

stop

female

mosquito

Aedes

aegypti

taking

a

a

the

Y ellow

on

cool

metamorphosis,

away

(Figure

the

10.2.3).

(nectar

are

her

its

blood

of

to

and

phloem

both

places

provide

types

to

the

sap),

but

live

in

protein

after

and

that

around

they

human

rest.

disease

vectors

parasites

life

from

cycle

salivary

meal

fever

is

from

clotting

caused

mosquitoes.

to

by

Dengue

disease

occurs

of

disease.

the

person

inside

glands.

an

as

by

the

When

she

gut

is

of

Transmission

uninfected

she

the

feed

on

when

when

aegypti,

person,

the

female

feeding

the

is

mosquito

complete

injecting

feeds

from.

The

and

when

her

she

saliva

to

feeds.

yellow

they

infected

which

fever

infected

feed

on

humans

then

virus,

animals

them.

to

the

is

transmitted

forests,

The

return

transmits

which

in

then

greatest

urban

virus

to

pass

risk

areas

other

of

and

the

an

are

humans.

fever

fever

is

They

humans

Aedes

Dengue

is

caused

increasing

by

a

across

virus

the

transmitted

world,

by

including

mosquitoes.

the

This

Caribbean

Anopheles

(T able

10.2.1).

Epidemics

tend

to

occur

feeding

population

148

fly

fever

epidemic

female

to

blood

infection

mosquitoes

up

blood

Yellow

by

T wo

and

blood

meal

10.2.2

of

completes

moves

takes

Figure

complete

case

juices

on

Adults

dark,

mosquitoes

may

then

feed

eggs.

Transmission

A

plant

females

make

dwellings

10.2.1

After

pupal

livestock.

mating

Figure

the

of

Both crop

appearance.

human

of

mosquitoes

increases.

after

heavy

rains

when

the

fed

Malaria

Malaria

is

complex

from

caused

than

many

by

a

single-celled

bacteria

countries

or

by

viruses.

parasite

The

breaking

that

disease

the

is

has

much

been

transmission

more

eradicated

cycle.

Adult

Eggs Lar va

Pupa

Control

of

mosquitoes Figure

Mosquitoes

•

reducing

•

covering

are

the

the

controlled

10.2.3

The

life

cycle

number

of

places

surfaces

of

water

where

with

they

oil

or

can

lay

cannot

Anopheles

eggs

polystyrene

beads,

T able

so

10.2.1

Distribution

transmitted

larvae

of

mosquitoes

by:

of

vector-

diseases

in

the

breathe Caribbean

•

stocking

larger

bodies

•

spraying

insecticide

of

water

with

fish

that

eat

mosquito

larvae

Disease

in

houses

and

on

breeding

Countries

is

Plant

By

and

keeping

animal

livestock

monocultures

we

in

a

risk

of

cause

large

provide

epidemics.

the

Dengue

Throughout

fever

Caribbean

Malaria

Haiti,

selective

variation.

diseases

a

numbers

perfect

Almost

was

out.

and

grown

which

there

wiped

that

Crops

for

disease

be

breeding

is

they

a

all

attacked

are

over

and

growing

conditions

of

our

crop

genetically

wide

have

chance

This

for

crops

as

pathogens

to

Guyana,

plants

little

that

happened

by

a

areas

fungal

uniform

are

are

at

resistance.

varieties

with

the

disease

risk

If

with

Gros

with

the

of

and

identical

Michel

known

is

as

an

1950s.

grown

This

variety,

may

is

at

happen

risk

of

a

again

new

as

strain

of

this

the

Yellow

Trinidad

epidemic

screw-worm

fly

attacks

cattle

and

other

genotypes

of

fever

Guyana,

disease

most

in POINTS

commonly

A

vector

adults

lay

is

in

sharp

the

jaws

flesh

to

of

animals.

burrow

into

The

the

eggs

hatch

animals.

If

and

the

untreated

maggots

the

use

animals

consequences

of

plant

and

animal

diseases

death

of

livestock

•

expenditure

pesticides

on

and

and

loss

control

of

crops

measures,

fungicides

for

so

as

2

T wo

types

lose

drugs

money

less

•

possible

are

food

for

human

famine

destroyed

if

by

and

for

livestock

main

staple

widespread

is

dengue

and

fever

crops

animal

of

diseases:

fever

and

of

foods,

such

as

wheat,

rice

and

maize,

3

Adult

life

term

Redraw

the

roles

of

mosquitoes

as

by

State

the

are

life

likely

stages

in

controlled

cycle

(without

habitats

Summarise

the

populations.

habitats

bodies

diagram

of

mosquitoes

as

a

flow

chart

Growing

genetic

of

by

and

water

so

at

pictures).

of

the

larvae,

impact

of

pupae

plant

and

breathe.

risk

and

adults

of

crops

animal

with

variation

of

disease

them

out

limited

puts

that

and

them

may

lead

to

mosquitoes. reduction

5

other

cycle

cannot

wipe 4

are

spraying

vectors. 4

the

diagram

the

vector they

3

is

QUESTIONS

the

Describe

yellow

malaria.

mosquitoes

covering

2

and

of

Anopheles

controlled

disease.

draining

Define

Aedes

vector

consumption

the

1

mosquito

pathogens

the

insecticides;

SUMMARY

infectious

humans.

the

human

aegypti

vector •

that

are:

farmers

such

animal

their

die.

of

•

an

to

transmit The

an

their

disease eggs

Suriname

will

1

The

Tobago,

banana

disease.

livestock.

and

of

transmits The

Republic

genetic

and

variety

Panama

Cavendish,

the

result

little

pests

there

Belize,

spread

KEY the

the

region

Dominican

of

there

disease

diseases

Suriname

and

where

sites.

diseases

on

human

of

loss

of

and

possible

food

income

for

supplies,

farmers

famine.

149

10.3

Sexually

transmitted

infections

Sexually LEARNING

the

end

should

•

be

define

of

this

able

the

outline

the

•

STIs

occurs

during

prevent

Gonorrhoea

STIs

the

causative

and

how

gonorrhoea

agents

gonorrhoea

HIV/AIDS

are

and

treated

moist

either

of

and

be

The

first

bacteria

become

antibiotics,

Experts

the

for

bacterium

resistant

which

days

the

of

after

multiply

and

or

other

a

in

other

transmitted

intimate

ways,

homosexual

bacterium

or

woman

of

one

the

in

the

or

the

the

disease

the

when

may

female

to

infection.

within

multiply

pain

a

by

male

from

pain

Women

will

women

now

be

on

cases.

that

from

but

sexual

most

activity.

transmission

activity.

that

urethra

other

in

develop

urethra,

only

of

a

penis

an

inside

present

in

infection

intercourse.

between

the

producing

If

the

sexual

men

on

survive

tract.

man,

during

appear

Sores

can

reproductive

two

and

the

unpleasant

urinating.

cervix

notice

the

men

antibiotics

and

symptoms

have

will

and

as

and,

a

to

a

lesser

discharge

in

gonorrhoea

not

disease

long-term

soon

resistant

or

they

but

extent,

often

inside

there

the

may

be

no

realise

to

damage

women

to

the

infected

early

they

have

the

sexual

partners.

urinary

resulting

Most

their

that

other

men.

from

in

and

men

symptoms,

infection

If

not

will

and

treated,

reproductive

know

whereas

may

there

systems

many

pass

may

of

be

both

sterility.

to can

be

treated

effectively

by

antibiotics.

However,

as

with

cases many

go

caused

of

vagina.

that

many

some

warned

bacterium

to

are

treating

have

suitable

will

is

vagina

Gonorrhoea all

are

during

KNOW?

gonorrhoea

useless

heterosexual

symptoms

seven

Bacteria

has

(STIs)

people

transmitted

transmitted

discharge

The

be

lining

the

can

to

controlled.

YOU

uninfected

Gonorrhoea

to

the

to

sexually

infection

of

outline

DID

may

ways

HIV/AIDS

•

you

people

transmission

state

the

topic

Some

to:

term

transmitted

•

infections

OUTCOMES infected

At

transmitted

(STIs)

diseases,

prevention

is

better

than

cure.

The

following

steps

untreated. can

•

be

taken

Have

only

infection

•

If

the

•

If

a

prevent

one

is

man

another

to

partner;

not

uses

person

be

spread

of

is

a

both

condom

and

he

is

diagnosed

traced,

the

if

partners

are

disease-free,

then

possible.

person

should

infection:

the

bacteria

unlikely

with

warned

to

cannot

be

gonorrhoea,

and

treated

pass

through

it

to

infected.

then

with

all

sexual

antibiotics

contacts

to

stop

the

disease.

HIV/AIDS

In

1982,

patients

of

doctors

with

result

of

condition

AIDS.

virus Figure

10.3.1

Across

many

who

by

150

the

world

children

have

been

HIV/AIDS.

there

like

rare

pneumonia.

the

The

–

in

North

conditions

Scientists

immune

was

called

causative

human

America

and

especially

discovered

systems

that

acquired

agent

of

in

a

that

did

Africa

rare

cancer

these

not

began

collapse

function

immunodeficiency

in

virus

the

or

and

rare

form

were

efficiently.

This

syndrome

immune

HIV .

see

a

conditions

immunodeficiency

this

to

AIDS

system

is

a

or

is

collection

are

these

orphaned

of

different

People

who

diseases.

diseases,

have

The

some

AIDS

do

condition

is

cancers

not

now

and

always

some

have

generally

infectious

the

same

known

as

a

diseases.

collection

HIV/AIDS.

of

Transmission

of

HIV DID

HIV

does

not

survive

for

long

outside

the

human

body.

It

is

an

infected

person

to

an

uninfected

person

in

body

infectious

in

semen

and

vaginal

fluids

during

unprotected

(unsafe)

blood

if

as

there

is

blood-to-blood

contact

between

two

of

the

example

intravenous

drug

users

sharing

needles

to

a

such

surgical

•

in

•

from

that

Treatment

as

caused

is

mother

Anti-viral

heroin,

instruments

blood

such

as

of

drugs

by

baby

control

not

‘needle

stick’

sterilised

transfusion

during

now

the

and

bacteria

is

in

by

if

birth

accidents

in

hospitals

people

there

is

still

spread

anti-fungal

and

very

newly

no

large

proportion

who

have

died

the

of

fungi.

much

infected

cure

early

it

is

and

not

in

heat-treated

breast

to

kill

HIV

enters

the

genetic

virus

for

1980s

milk.

The

of

HIV

drugs

life

higher

in

the

body

control

expectancy

than

and

other

opportunistic

it

used

a

normal

for

to

people

be.

Some

drugs,

infections

living

with

doctors

think

now

the

will

live

condition

and

no

life

vaccine

span.

(as

of

10.3.2

This

However ,

lymphocyte

HIV

particles

released

2013).

it

is

estimated

that

about

30

million

people

enters

DNA

the

in

material.

body

the

The

These

it

infects

nucleus

result

‘bud’

is

and

that

off

a

certain

uses

the

from

it

to

type

make

lymphocyte

the

of

surface

to

lymphocyte.

many

fills

copies

up

infect

with

other

It

of

1

its

new

agent

cells

of

human

virus

drugs

nausea,

the

fever,

virus

used

is

to

treat

copied.

HIV

diarrhoea,

skin

These

disrupt

rashes

drugs

the

and

have

way

mood

side

the

of

mothers

who

have

HIV

has

the

such

virus

infection

to

babies.

and

need

If

a

this

is

not

lifetime

of

done,

babies

are

2

transmission

often

They

of

the

spread

of

effective

born

with

sex.

way

Other

to

control

barrier

treatment.

3

HIV

the

spread

diaphragm

or

semen

vaginal

and

cap,

are

not

of

of

HIV

is

the

effective

contraception,

use

as

there

is

still

such

of

as

contact

HIV

Describe

the

Distinguish

3

Describe

between

4

fluids.

a

of

decrease

of

those

in

lymphocytes

infected

opportunistic

as

TB,

and

HIV

is

at

high

infections,

cancers.

transmitted

unprotected

transmission,

treatment

and

control

5

of

at

sex,

contact,

during

blood-to-

breast

feeding

between

HIV

and

6

AIDS.

different

ways

in

which

HIV

is

birth.

Anti-retroviral

used

three

to

treat

Preventing

is

by

the

steps

of

HIV

that

can

be

infection.

taken

to

reduce

drugs

are

HIV .

the

spread

health

of

awareness

transmitted. campaigns,

cases

a

the

HIV

new

with

QUESTIONS

2

Explain

cause

treated

condoms

gonorrhoea.

4

(STIs).

antibiotics.

number

and

1

may

is

causes

blood SUMMARY

it

of

making

methods

infections

the

such during

are

of

risk One

the

sexually

Gonorrhoea

the

Controlling

is

as

course the

by

causative

genetic

effects,

swings.

reduced

many

immunodeficiency

(HIV).

sterility; Treatment

caused

the

HIV/AIDS

transmitted of

infect

of

are

lymphocytes.

is

bacterium;

examples

material

full

POINTS

Gonorrhoea

a

10.3.2).

Anti-retroviral

to

is

which

have

KEY

particles.

(Figure

AIDS.

HIV

AIDS.

When

and

of

thoroughly

other

Since

is

common

if

Figure

that

T uberculosis

most

HIV/AIDS

antibiotics

HIV/AIDS

are

used

to

and

are

inject

people drugs

that

HIV

people,

infects for

with

opportunistic

infections.

one in

people

known

sexual

intercourse

•

diseases

fluids: infect

•

KNOW?

passed The

from

YOU

the

number

of

especially

encouraging

men

to

use

condoms.

151

Unit

SECTION

Much

of

disease

need

to

use

1:

in

know

them

answer

information

the

information

Practice

Short

the

is

to

10

form

how

by

of

to

they

questions

questions

you

will

tables

make

analysing

that

exam

find

and

these

and

about

charts.

and

Try

of

how

interpreting

present.

Figure

You

Ribeirão

the

drawing

2

all

shows

dengue

Preto,

between

the

fever

2000

number

reported

São

and

in

Paulo

of

new

the

State,

cases

city

of

Brazil

2009.

of 2500

the

graphs

find

this

with

advice

section,

those

on

on

and

the

selecting

CD.

and

then

check

There

you

drawing

the

your

will

correct

eugned

answers

in

2000

fo

for

disease

refer

some

1

but

to

of

other

other

the

Aedes

topics

units

answers

aegypti

of

is

as

in

to

the

data

–

well.

this

You

book

these

vector

not

only

may

for

on

need

help

with

questions.

of

several

ylhtnoM

to

presentation

sesac

graphs

1500

1000

500

diseases

0

including

a

dengue

Explain

in

the

what

fever.

is

context

meant

of

by

the

pathogenic

term

diseases.

life

1

cycle

shows

of

two

Aedes

stages,

A

and

Jan

Jan

Jan

Jan

Jan

2002

2004

2006

2008

2010

(2)

Figure

Figure

Jan

2000

vector

B,

in

2

the

aegypti. c

i

Describe

dengue

ii

Suggest

you

A

the

an

have

i

Explain

in

outbreaks

Figure

explanation

for

of

2.

the

(4)

pattern

(3)

data

such

as

on

pathogenic

that

shown

in

Figure

1

2,

ii i

of

described.

why

diseases,

b

shown

B

d

Figure

pattern

fever

Name

the

stages

and

state

their

may

not

Suggest

be

steps

accurate.

that

(2)

health

authorities

habitat. should

take

to

reduce

people

infected

the

number

of

(2)

ii

Outline

what

happens

in

the

life

during

an

outbreak

dengue. between

stages

A

and

B.

Explain

how

these

two

stages

Name

another

disease

that

is

transmitted

are by

controlled.

(4)

(3) e

iii

Aedes

aegypti.

(1)

(4) Total

152

of

cycle

25

marks

2

a

State

three

ways

in

which

HIV

is

T able

transmitted.

1

(3) Year

T able

1

shows

the

number

of

new

Gender

reported not

cases

of

HIV

between

b

1982

Present

cases

c

Use

infection

the

in

T able

1

in

Scientists

state

that

the

between

males.

percentage

T able

seven

2

of

in

shows

has

living

female

known

T otal

the

(4)

for

region

females

the

is

on

the

HIV

0

2

0

2

1986

238

84

0

322

1988

370

161

34

565

1990

755

469

76

1300

HIV/

1992

1020

661

134

1815

1994

1095

735

220

2050

1996

1198

866

274

2338

1998

1219

966

305

2490

2000

1572

1205

309

3086

2002

1817

1484

96

3397

2004

1670

1495

66

3231

2006

1865

1779

479

4123

2008

1815

1789

26

3630

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570

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proportion

infection.

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1984

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data

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data

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from

Indexmundi.com

Further

and

on

practice

examples

the

questions

can

be

found

accompanying

CD.

153

11

Genes

and

11.1

inheritance

DNA

Nucleus LEARNING

The At

the

end

of

this

topic

be

•

that

nucleus

able

genetic

matter

DNA

the

activities

chromosomes.

and

from

deoxyribonucleic

histones.

the

wound

the

inheritance

transmitted

to

is

material

of

controls

are

of

These

cells.

are

Contained

thread-like

within

the

structures

made

to: from

state

chromosomes

you nucleus

should

and

OUTCOMES

that

is

Each

around

molecule

of

acid

chromosome

the

DNA

histones

can

be

up

(DNA)

has

and

one

proteins,

very

as

you

can

to

50 mm

long

see

in

known

molecule

Figure

as

of

DNA

11.1.1.

Each

long.

generation

Strand

generation

of

•

define

the

terms

gene

DNA

and

chromosome

•

define

the

term

chromosomes

homologous

and

recognise

Histone

pairs

•

of

explain

them

the

in

significance

of

Figure

haploid

of

and

diploid

chromosomes

animal

life

in

plant

between

is

each

the

chromosome

genetic

is

packed

material;

the

around

histones

histone

provide

molecules.

structural

The

support.

organism

has

a

certain

number

of

chromosomes

in

each

nucleus.

genes number

is

not

associated

with

the

complexity

of

the

organism.

alleles Humans

fern,

have

which

Figure

pairs

46

has

11.1.2

based

sex

on

are

the

same

that

genes.

were

each

Life

pair

in

the

was

cycle

of

A

research

studies

images

of

X

and

shape.

A

and

zygote

when

from

numbers

do

In

into

pair

shapes.

the

chromosomes

chromosomes

sorted

Y .

cells;

of

are

X

he

his

can

each

be

photograph

homologous

the

same

Y

are

size

not

was

conceived.

and

the

held

One

other

a

a

man’s

pairs

and

the

homologous

and

are

by

into

shape

and

homologous

chromosomes

father

is

is

nucleus.

sorted

chromosomes

and

The

the

22

in

record

copies

as

of

have

they

those

chromosome

from

his

in

mother.

The

in

number

YOU

not

reproducing

the

in

number

a

remain

gametes

zygote

(2n).

In

constant

organisms

is

(Figure

called

and

in

the

cells

humans,

n

throughout

11.1.3).

haploid

derived

=

23

2n

the

=

46.

human

all

the

DNA

is

in

and

the

nucleus.

chloroplasts

There

that

are

have

small

loops

genes

for

of

DNA

these

cell

homologous

structures.

process

Scientists

known

as

are

using

‘barcoding’.

this

DNA

to

identify

species

(n

for

zygote

KNOW?

mitochondria

life

number

number

from

and

the

The

arranging

in

pairs.

and

been

inherited

sexually

diploid

Not

into

size

the

body

worker

chromosomes,

them

that

Chromosomes

chromosomes

DID 11.1.2

thousand

of

cycles

short).

the

a

nucleus

chromosomes

sizes

Chromosome

of

their

have

two

different

each

over

chromosomes,

because

the

in

shows

chromosomes

154

in

DNA

and

The

Figure

DNA

cycles

distinguish

and

11.1.1

numbers

Each

•

molecules

diagrams

–

a

is

LINK

Adult

male

(2n)

Adult

female

Question

(2n)

the Growth

and

7

on

page

chromosomes

168

of

a

shows

female

Meiosis

muntjac

development

Haploid

sperm

(n)

Haploid

egg

deer.

Make

sure

(n)

that

for

you

know

when

what

identifying

to

look

pairs

of

Mitosis Diploid

multicellular Diploid

embryo

zygote

homologous

(2n)

(2n)

Also

the Figure

11.1.3

Genes

The

as

is

and

length

genes.

make

a

of

for

a

that

of

Each

used

in

of

four

of

sequence

a

gene

a

protein.

it

change

to

the

an

showing

A,

acid

of

the

position

G

three

in

and

of

meiosis

and

other

for

A

Cells

bases

into

amylase

20

‘read’

(e.g.

amino

(see

guanine

sequence

are

segments

assembling

or

thymine,

C.

There

DNA

can

can

of

ATC)

four

and

different

cytosine,

amino

for

to

acids

in

one

codes

groups

of

the

changes

may

be

or

are

the

Such

a

change

sequence

very

of

significant

functions

in

life-threatening,

a

and

different

as

you

to

DNA

amino

will

is

acids

change

way.

see

in

the

This

the

changes

are

beneficial,

as

you

will

see

in

in

Unit

11.6.

forms

of

a

gene

are

known

as

alleles.

In

some

are

two

alleles,

alleles

but

for

each

a

gene;

diploid

some

genes

organism

can

within

only

a

species

have

two

part

of

This

DNA.

model

Note

the

shows

double

a

very

helix

and

cases four

bases,

A,

T ,

C

and

G,

which

together

have make

many

11.1.4

12.

the

there

about

DNA

bases

bases

codes

acids

small

The

more

known

5.4).

these

different

the

change.

affect

function,

protein

cases

for

mitosis

Figure

In

11.7

chromosomes.

11.1.4).

this

the

not

and

acids.

divided

catalase

adenine,

T ,

(Figure

bases

does

as

proteins.

of

is

instruction

such

amino

Sometimes

so

animals

bases:

make

mutation

protein

of

chromosome

is

to

group

amino

a

gene

to

Each

cycle

protein,

of

sequence

three.

The

DNA

abbreviated

are

types

life

see

sex

alleles

specific

composed

usually

The

chromosomes.

of

them.

up

stands

the

for

genetic

the

sugar

code.

that

The

is

letter

part

of

D

the

DNA

molecule.

KEY

POINTS

SUMMARY

1

Chromosomes

proteins;

material

they

that

are

are

made

of

located

codes

for

the

in

the

nucleic

cell

nuclei.

synthesis

of

acid

DNA

DNA

is

and

the

proteins

genetic

from

QUESTIONS

histone

1

amino

Arrange

by

acids.

size,

these

smallest

histone,

DNA

is

is

the

passed

material

from

of

generation

to

generation

in

gametes

Homologous

inheritance.

chromosomes

2

are

the

same

size

and

shape

Explain

the

the

same

Diploid

cells

5

A

have

gene

an

cells

is

allele

protein,

6

A

a

is

but

mutation

code

for

of

two

is

the

of

different

in

a

a

of

each

length

a

difference

of

pairs:

the

chromosome

genes.

have

one

cell.

and

and

4

and

each

following have

largest:

gene,

and

between 3

to

nucleus,

chromosome 2

structures

each

type

of

chromosome;

haploid

haploid

type.

DNA

form

different

change

sequence

of

codes

a

gene

for

a

that

specific

codes

protein;

for

the

3

same

the

the

nuclei

sequence

amino

acids

in

of

bases

in

proteins.

DNA

that

and

and

State

gene

4

of

Explain

when

and

allele;

diploid;

amino

protein.

number

chromosomes

way.

to

of

acid

that

gene;

all

of

the

haploid

humans.

what

there

in

happens

is

a

to

DNA

mutation.

155

11.2

Mitosis

A LEARNING

cell,

such

surface

At

the

end

should

be

of

this

able

topic

define

the

larger,

to:

following

area

enough

you

this

•

division,

•

outline

cell

can

nuclear

grow

sustain

division

itself.

occurs

there

is

would

by

getting

a

decrease

larger

Therefore

and

each

nuclear

cell

and

for

an

because

would

not

organism

divides

division.

it

its

into

The

two.

to

get

grow

Before

nucleus

divides

so

that

each

new

cell

has

the

genetic

information

it

by

needs

division function.

the

events

that

occur

state

that

mitosis

number

of

a

of

role

of

mitosis

replacement

repair

copies

of

must

the

be

genetic

made.

information

This

happens

in

the

before

divides.

and

During

copying,

the

DNA

in

the

chromosomes

the

is

in

of

and

arranged

very

loosely

in

the

nucleus.

After

copying,

cells, each

tissue

new

chromosome

chromosomes

uncoiled growth,

divides,

each

nucleus the

cell

maintains

DNA

state

mitosis

mitosis

Before

•

to

happen,

Before

the

cannot

ratio

mitosis

during

•

zygote,

volume

terms:

to

and

a

to

oxygen

mitosis,

cell

as

OUTCOMES

chromosome

consists

of

two

copies

of

all

DNA

material.

As

asexual mitosis

begins,

the

DNA

coils

up

tightly.

Each

chromosome

appears

reproduction. as

a

are

double-stranded

chromatids.

During

Figure

so

time

As

of

Figure

11.2.1

An

example

of

a

a

shows

divides

what

you

human

result

of

plant

numbers

the

to

plantlets

cell

like

each

the

to

four

Human

diagram

divides

as

happens

mitosis.

the

mitosis

is

one

occurs

Growth

identical

strands

replication

chromosomes

cells

happens

have

to

all

46

46

as

the

chromosomes,

chromosomes

each

this.

daughter

original

copied

by

another

cell

parent

has

cell.

the

As

same

the

number

a

reliable

system

they

DNA

are

in

the

genetically

and

to

the

parent

cell.

in:

–

•

Tissue

the

•

• cane

all

and

genetically

will

crop

give

when

Fields

of

a

cannot

the

of

all

cane

are

a

clone.

same

–

such

–

cells

for

(see

a

or

7.4

and

example,

wear

of

the

animal

meristems

wounds

short

T able

–

as

(see

for

repair

division

plant

out

time

the

and

as

and

in

plants

later

and

it

is

the

9.1).

stem

in

zygote

embryo;

die,

they

cells

skin

at

such

do

the

(see

as

not

base

of

8.8).

red

have

blood

a

nucleus

7.4.1).

occurs

kingdom.

All

in

the

fungi

and

organisms

in

plants,

produced

but

by

is

rare

asexual

wiped

disease.

from

one

Identical

individual

twins

are

are

a

genetically

clone

as

they

identical

are

and

formed

from

a

same

embryo

that

splits

into

two.

The

plantlets

that

are

at

on

the

leaves

of

the

Mexican

hat

plant,

Bryophyllum,

out

vegetative the

live

to

reproduction

reproduction

form

are

which

being

cells

divide

animal

produced risk

of

only

a

bones

repair

divide

first

of

places,

long

wound

which

Asexual

the monoculture,

and

in

the

body

identical

uniform

harvested.

sugar

regions

with

the

cuttings

in are

starts

certain

Replacement

and

sugar

to

epidermis

cells,

These

this

throughout

growth

156

is

from

restricted

by

DNA

leaves.

then

11.2.2

genetically

large

•

Figure

two

copying

Mexican

produces

of

in

chromosomes

Mitosis its

The

of

asexual

identical hat

what

during

see

chromosomes reproduction:

process

mitosis

11.2.3

nucleus

structure.

The

reproduction

are

a

clone

(see

Figure

11.2.1).

by

Parent Cell

cell

membrane

Chromosome 1

The

chromosomes

they

Cytoplasm

can

be

shorten

seen

under

a

and

thicken;

light

microscope.

Nuclear

membrane

Chromatids 2

Due

to

replication,

double

stranded

identical

Centromere

each

with

chromosome

two

is

genetically

chromatids.

Figure

3 Equator

The

chromosomes

11.2.4

In

in

the

middle

(equator)

of

the

membrane

around

the

photograph

growing

nucleus

root

has

the

disintegrated.

tip,

of

of

can

a

that

see

stages

are

of

drawn

in

of Figure

movement

the

you

different

mitosis

Direction

region

cell.

cell The

this

linea

up the

double-stranded

of

of

4

The

chromatids

chromatids

separate

to

stranded

chromosomes.

opposite

poles

of

the

form

These

11.2.3

(× 170).

single-

move

to

cell.

LINK

See 5

The

single-stranded

are

now

the

cytoplasm

divided

in

to

the

daughter

of

form

10.2

and

the

two

nuclei

original

Figure

11.2.3

Mitosis

in

an

has

crops,

sugar

such

animal

When

is

meant

by:

chromosome,

chromatid,

it

a

cell

reaches

divides

division;

into

a

certain

two

nuclear

by

division

mitosis

occurs

before

the

division cytoplasm

a

genetically

variation.

mitosis by

2

are

little

QUESTIONS

what

cell

which

with

POINTS

cell

and

and

cell

size

Explain

cane

cells

1

1

as

cells.

KEY

SUMMARY

the

having

and

cell

daughter

of

uniform Daughter

for

consequences

bananas,

2

12.4

chromosomes

Describe

what

happens

inside

a

cell

before

it

can

divide

divides.

by 2

Mitosis

is

a

type

of

nuclear

mitosis. division, b

Describe

what

happens

to

a

chromosome

during

which

Describe

what

happens

to

a

cell

after

mitosis

is

Make

models

cleaners

what

4

Human

The

to

of

wool

or

using

string.

chromosomes

modelling

Use

when

your

cells

clay,

pipe

models

divide

by

to

show

blood

cells

do

not

live

very

long

and

mitosis.

why

in

Figure

11.2.4

must

be

plant

Suggest

why

all

the

individuals

in

a

clone

the

Mitosis

but

may

not

look

always

number

as

the

of

parent

in

growth,

reproduction,

of

tissues

of

cells.

and

repair

replacement

cells.

are

Crops

that

are

produced

by

genetically

vegetative identical

nuclei

same

occurs

asexual

they

5 5

nuclei.

nucleus.

divide.

cells

daughter

chromosomes

4

red

The

have

why:

cannot

b

chromosomes

lengths

happens

Explain

a

or

of

identical

complete. 3

3

two

mitosis. genetically

c

forms

reproduction

are

alike.

genetically

risk

of

identical

being

wiped

and

out

at

by

disease.

157

11.3

Meiosis

If LEARNING

human

the

end

should

be

of

this

able

topic

define

the

generation

fertilisation

humans

to:

term

every

when

you

be

•

a

remains

different

explain

of

the

meiosis

importance

in

halving

chromosome

generating

•

describe

the

number

by

occurs.

the

type

Since

same

of

(at

nuclear

of

mitosis

it

would

chromosomes

mean

the

46),

number

in

every

division

of

would

that

chromosomes

generation

involved

double

in

the

there

in

must

production

this

the

number

in

and

and

the

from

which

also

halves

generates

daughter

each

the

cells

number

variation

are

of

chromosomes.

among

genetically

the

Meiosis

the

movement

gametes,

different

from

the

so

the

nuclei

parent

cell

other.

Cell

of

during

Parent

membrane

cell

Chromosome

chromosomes

chromatids

First

meiosis

Cytoplasm

division

Chromosomes

and

shorten

thicken. Nuclear

•

explain

the

role

of

meiosis

in membrane

sexual

reproduction Chromatids

•

state

when

meiosis

occurs

in Each

flowering

life

plant

and

animal

chromosome

genetically

has

identical

two

chromatids.

cycles.

Centromere

Equator

Homologous

form Diploid

cell

Diploid

ovar y

in

pairs

chromosomes

the

middle

of

the

cell

the

and

exchange

Homologous

parts

of

them.

chromosomes

46

Homologous

each

chromosomes

double-stranded

moving

to

opposite

separate,

Direction

chromosome

poles

of

the

of

cell.

Cell Haploid

Fertilisation

division

sperm

Nuclear

membranes

may

23 egg form

around

each

chromosomes.

46

cytoplasm

two

Diploid

11.3.1

divides

to

give

zygote

The

number

division

of

Chromosomes chromosomes

during

the

gametes

formation

in

restored

humans

to

the

middle

at

of

the

in

cell.

of

and

diploid

The number

are

halves

the

is

of

The

cells.

Second Figure

group

chromatids

Direction

separate

move

poles

of

to

the

movement

opposite

four

care

mitosis

word s

when

and

are

divide

daughter

to

form

cells.

writi ng

meiosis

very

cells

as

the

4

simila r .

Figure

158

division

TIP The

T ake

of

chromosomes

cells.

Cell

EXAM

of

fertilisation.

and

11.3.2

This

diagram

shows

the

two

Daughter

cells

divisions

of

of

movement

chromosomes

23

Haploid

pair

testes between

46

in

of

cell cell

in

of

does

variation

homologous

and

produced

process

meiosis gametes,

•

were

the

OUTCOMES in

At

gametes

–

meiosis

and

Figure

of

11.3.2

shows

chromosomes

divisions

of

diagram,

the

each

what

during

cell

of

to

happens

meiosis.

give

these

four

has

to

cells.

two

two

There

pairs

are

In

two

Reproductive

growth

the

chromosomes Flower

so

the

number

happening

to

give

has

within

four

been

a

cell

haploid

halved.

with

cells,

Imagine

46

each

this

chromosomes

containing

23 Diploid

chromosomes.

a

sperm

leave

cell.

one

In

In

the

the

large

testis

ovary,

haploid

each

three

cell

–

will

of

the

develop

the

egg

cells

into

die

cell

stamen

to

in

Diploid

(2n)

cell

carpel

in

(2n)

Vegetative

growth

cell.

and

Meiosis

development

In

meiosis

the

daughter

cells

are

not

Haploid

identical.

pollen

grain

They

to

are

genetically

genetic

evolve

in

different

variation

response

which

to

and

this

allows

changing

of

flowering

(n)

organisms

to

environments.

in

cycle

embr yo

sac

contributes

Haploid

Life

Haploid

(n)

male

pollen

nucleus

tube

Female

(n)

gamete

embr yo

sac

in

(n)

plants

Fertilisation

This

differs

meiosis

from

occurs

that

in

the

of

animals.

production

In

animals,

of

gametes Diploid

(see

Figure

11.1.3).

In

flowering

plants,

multicellular

embr yo

results

both

and

in

pollen

divide

female

grains

further

by

gametes,

and

embryo

mitosis

to

sacs.

give

respectively.

Diploid

(2n)

(2n)

These

the

male

Anthers

Figure

11.3.3

Meiosis

of

contain

occurs

pollen

released,

many

diploid

cells

that

divide

by

zygote

meiosis

meiosis

to

in

grains

flowering

and

embryo

plants

embryo

sacs

in

sacs.

remain

in

the

production

Pollen

the

grains

ovule

are

inside

the

produce ovary.

pollen

ovule

One

cells

one

grains,

one

of

from

diploid

these

die.

of

The

embryo

cell

is

the

to

sac

then

fuses

the

by

form

female

tube

within

haploid.

divides

embryo

pollen

sac

are

develops

which

the

which

In

meiosis

a

divides

with

developing

to

haploid

gamete.

ovule

the

a

by

At

mitosis

four

sac.

to

fertilisation

haploid

(Figure

produce

embryo

female

form

a

haploid

The

other

several

haploid

gamete

in

cells.

three

cells,

nucleus

KEY

the

POINTS

11.3.3). 1

Meiosis

have

produces

half

the

chromosomes SUMMARY

The

the

parent

number

chromosomes How

as

that

of

QUESTIONS

nucleus.

1

nuclei

number

many

chromosomes

are

there

in

the

following

in

of

daughter

human

nuclei

is

the

haploid

number.

cells:

a

a

cell

c

a

from

sperm

the

cell,

lining

d

a

of

an

zygote,

alveolus,

e

a

red

b

an

blood

egg

cell,

2

cell?

Haploid

that

2

a

State

the

products

of

meiosis

in

animals

and

3

There

in Each

leaf

cell

of

an

onion

has

16

has

to

form

the

chromosome

numbers

chromosomes;

what

are

two

meiosis.

a

pollen

grain,

ii

a

sac,

iv

a

root

tip

cell,

iii

a

nucleus

in

a

State

b

Explain

three

ways

the

in

xylem

which

advantages

in

the

division

In

and

the

then

second

vessel?

meiosis

of

pair

an

division

3

divisions

Homologous

are

separate. embryo

number.

in:

first i

zygote

diploid

chromosomes the

fuse

a

flowering

plants.

b

gametes

together

differs

genetic

from

variation

mitosis.

each

the

chromatids

chromosome

of

separate.

among 4

In

animals,

meiosis

produces

gametes. haploid

4

Use

two

models

of

divisions

chromosomes

of

meiosis.

to

show

what

happens

during

the

plants,

gametes;

pollen

embryo

sacs

in

grains

are

the

flowering

and

products.

159

11.4

Meiosis

Random LEARNING

At

the

end

should

be

explain

meiosis

genes

the

•

of

this

able

the

topic

One

way

is

‘shuffle’

to

in

in

which

the

the

transmission

one

in

during

of

of

generation

to

which

the

randomly

with

23

and

roles

of

random

genetic

to

pass

state

the

on

as

random

the

of

to

pairs

Make

and

some

use

what

one

(see

two

homologous

meiosis.

middle

of

the

the

23

next

of

pairs,

The

the

giving

chromosomes

different

cell.

There

generation.

assortment

across

in

the

a

–

think

random

middle

in

Summary

Now

are

imagine

many

many

The

pairs

mixtures

random

are

are

of

arranged

arranged

this

possible

happening

random

chromosomes

arrangement

about

sorting

out

of

fashion

the

cell.

on

It

either

is

a

side

good

the

of

idea

question

is

known

homologous

an

to

imaginary

model

this

as

2.

A

Cell

B

pair

to

to

to

show

and

during

crossing

and

model

(Figure

during

variation.

them

11.3)

to

then

random

11.4.1).

Haploid

Figure

11.4.1

the

B.

any

cell

about

chromosome

The

adult

This

means

Crossing Homologous

Crossing

over

to

of

A

differ

divide

be

by

random

alleles

from

those

as

the

gametes

see

how

from

there

in

cell

is

by

by

the

parent

is

A

a

that

that

the

random

nuclei

cell

chance

50%

as

gametes

of

assortment

produced

from

B.

50%

and

combinations

produced

all

–

assortment

different

of

into

meiosis

arranged

gametes

of

variation

chromosomes

cells

in

that

cell

from

one

chromosomes.

organism

have

different

genes.

over

Chromatid

chromosomes

material

During up

meiosis,

homologous

chromosomes

exchange

parts

between

exchanged

them

11.4.2

cell

contain

that

combinations

introduces

will

advantage

organism

Haploid

homologous

parent

For

cells

Meiosis

of

Crossing

over

homologous

are

the

160

two

of

happens

11.4.2)

pairs

assortment

Figure

gametes

shows

between

chromosomes

introduce

(Figure

pair

between

11.4.1

meiosis.

models

happens

meiosis

over

to

with

what

Figure

FOCUS

understand

Start

variation

assortment

differences

homologous

meiosis

of

of

chromosomes.

Cell

STUDY

the

variation

suggested mitosis

generates

chromosomes.

crossing

plate •

of

division

across

pairs

arrangements

the

meiosis

pairs

two

first

chromosomes in

chromosomes

to:

next

over

of

you

importance

from

outline

assortment

variation

OUTCOMES

ways

•

and

paired

first

occurs

when

as

you

crossing

can

over,

see

also

in

Figure

11.4.2.

introduces

This

process,

known

as

variation.

chromosomes

together

division

of

during

meiosis.

Variation

two

in

the

processes

genetic

that

material

occur

in

in

the

meiosis.

gametes

Few,

if

any,

results

from

gametes

these

produced

during

an

variation

and

the

the

organism’s

is

caused

gametes

opportunity

variation

is

changing

Some

leads

to

lifetime

fuse

for

at

genetically

The

random.

even

more

See

flowering

self-fertilisation.

12.2

plant

Even

These

of

exactly

choice

The

survival

and

reproduce

the

the

mate

two

same.

is

often

factors

advantage

of

12.3

though

of

other

variation.

chances

environment.

of

are

fertilisation.

increase

species

to

at

the

for

by

next

more

introduce

of

all

this

generation

about

and

in

a

this.

self-pollination,

male

Further

random

female

which

gametes

EXAM

have

come

limited

plant

from

variation

are

not

reproduction

offspring

are

the

so

same

that

exactly

there

the

the

is

individual,

no

genetically

next

same

meiosis

generation

genetically.

meiosis

and

identical,

no

introduces

of

self-pollinating

Remember

fusion

forming

a

a

of

that

in

gametes,

clone

(see

9.2

Rem embe r

asexual

so

all

and

halves

the

num ber

varia

the

of

mitosis

and

11.4.1

summarises

the

meiosis

differences

and

tion

produc ed.

between

mitosis

and

11.4.1

The

differences

between

mitosis

and

meiosis.

and

meiosis

are Feature

Mitosis

no t

the

of

divisions

of

the

amon g

chan ge

cells

1

2

paren t

o ther

the

num ber

produc ed

gene tically

each

are

Mito sis

identic al

Meiosis

to

Number

resul ts

that

chrom osom e

T able

meio sis

chrom osom e

gam e tes

does T able

the

that

11.2).

in

Comparison

TIP

some

and

to

the

cell.

nucleus

Pairing

of

homologous

No

Yes

No

Yes

2

4

chromosomes

Crossing

Number

nuclei

over

of

daughter

produced

Genotypes

of

Identical

to

the

All

are

different

from

SUMMARY daughter

nuclei

parent

to

nucleus

each

and

each

other

other

parent

and

to

nucleus

1 Roles

in

organisms

Growth,

QUESTIONS

the

Production

of

in

production

a

State

three

meiosis

replacement

of

cells

animals;

ways

in

which

gametes differs

from

mitosis.

and

tissues,

wound

of

pollen

grains b

repair ,

asexual

and

embryo

sacs

Explain

the

genetic reproduction

flowering

advantages

of

in variation

among

plants gametes.

Chromosome

numbers

Same

as

the

parent

Half

the

number

as

2 of

daughter

nuclei

nucleus

the

parent

Use

to

be

KEY

models

of

POINTS

show

how

Gametes

differ

from

each

other

as

they

have

random

assortment

of

of

chromosomes

homologous

as

pairs

a

in

result

the

of

first

the

first

Crossing

over

occurs

in

meiosis

and

division

involves

of

meiosis.

3

a

Use

between

chromosomes

in

a

the

homologous

division

swapping

Figure

Mitosis

and

division;

meiosis

meiosis

variation;

nuclei

are

halves

the

the

produced

two

different

chromosome

by

mitosis

are

of

types

of

in

meiosis.

11.3.2

of

the

to

make

stages

of meiosis,

but

include

pair. crossing

3

by

chromosomes

drawing

of

DNA

meiosis

arrangements

random

a

2

in

can

different the

combinations

variation

generated

the

homologous

1

chromosomes

nucleus

of

number

and

genetically

generates

identical.

over

homologous

nuclear

b

Explain

the

crossing

between

a

pair.

advantage

of

over.

161

11.5

Genetics

Genetics LEARNING

is

the

characteristic

At

the

end

should

be

of

this

able

topic

from

you

define

the

following

phenotype,

trait,

dominant

allele,

allele,

The

recessive

trait,

recessive

homozygous

make

and

genetic

explain

the

crosses

and

diagrams

results

dominant

we

see,

of

can

to

inheritance

short

a

between

and

fruit

single

fly.

We

of

genes.

have

Each

learnt

Monohybrid

characteristic,

their

recessive

such

11.5.2

all

in

wings

gene

ability

appearance

as

wings,

for

and

an

biology

humans.

and

We

example

have

(see

and

the

shows

flies

alleles

is

organism’s

organism,

Almost

of

an

groups

Figure

genetic

investigations

an

two

distinguish

a

phenotype

of

of

inheritance

•

of

organism.

determines

aspects

blood

heterozygous

•

the

of

which

an

gene

lot

controls

about

inheritance

such

to

a

a

as

the

genetics

concerns

wing

length

the

of

fruit

fly.

terms:

genotype,

dominant

of

studying

inheritance

to:

flies

•

study

OUTCOMES

the

are

wing

wings,

unable

to

to

make

an

use

individual.

its

features

often

that

of

but

fly.

sure

genes.

the

length

inheritance

long

11.1

of

except

in

fruit

gene

you

to

flies

in

the

such

one

as

feature

11.5.1).

fruit

that

wings

the

to

all

features

(Figure

some

for

know

to

see,

apply

length

are

refers

includes

cannot

term

wing

there

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we

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It

flies.

have

very

therefore

difference

has

between

allele).

traits. A

male

and

with

then

amongst

Parental

long

males

wings

and

is

crossed

females

of

with

the

a

next

female

with

generation

short

are

wings

crossed

themselves.

generation

First

generation

(F

)

Second

generation

large

males

all

numbers

and

with

–

large

numbers

2

of

of

flies

females

long

)

(F

1

–

of

and

both

sexes

smaller

wings

with

with

number

short

long

of

wings

flies

wings

×

Male

Female

flies

F

were

allowed

1

to

Figure

11.5.1

Fruit

to

flies

keep,

produce

and

The

are

Figure

easy

short

offspring

life

spans.

disadvantage

You

can

is

wings.

that

they

see

This

that

wing

short

the

flies

The

a

that

the

reces sive

le tter .

the

fo r

we

the

that

fruit

long

flies

not

in

wing

recessive

in

the

can

has

see

trait.

that

been

first

allele

alleles

and

a

appear

in

the

first

generation.

the

is

fi rst

the

generation

dominant

have

trait

long

From

the

results

in

the

and

second

the

recessive

passed

on,

but

trait

did

reappears

not

affect

so

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the

allele

wings

of

generation.

used

flies,

of

is

to

the

refer

there

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genetic

is

gene

a

to

the

gene

and

composition

alleles

that

they

are

of

of

the

controls

an

organism.

genes

wing

represented

being

length.

in

a

The

term

investigated.

There

genotype

are

by

two

letters:

the for

the

allele

for

long

wings,

and

w

for

the

allele

for

short

wings.

smal l

differe nt

alleles

gene .

genotype

fruit

of

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parental

they

come

wings

only

for

have

Genetic

162

all

the

wing

usually

In

W

as

use

the

is

alwa ys

le tter

allele

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same

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domin ant

capita l

le tters

does

TIP

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as

feature

fly!

for

show

recessive

shows

is

generation,

EXAM

The

for

short researchers

11.5.2

easily,

many

have

only

small,

mate

interbreed

generation

from

many

the

a

stock

in

of

this

generations.

allele,

diagrams

W,

are

investigation

fruit

and

drawn

flies

As

a

that

result

we

short-winged

to

explain

are

had

know

flies

how

pure

either

the

only

the

breeding

long

wings

flies

or

long-winged

have

alleles

the

are

as

short

allele,

flies

w.

inherited.

Parental

phenotypes

Male

long

Female

wing

×

short

wing

EXAM Parental

genotypes

Parental

gametes

WW

TIP

ww

+

W

When

w

you

gene tic F

genotype

write

out

diag rams

Ww

like

1

this F

phenotype

All

long

one,

wing

mak e

them

1

F

phenotypes

Long

wing

×

Long

simpl e

wing

–

homoz ygou s

1

organi sms F

genotypes

Ww

only

mak e

Ww

1

gam e tes F

of

one

gametes 1

w

,

W

W

+

w

,

so

only

the Male

gametes

a

grid,

WW

this

Ww

to

once

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calle d

possib le

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write

diag ram .

squa re,

W

geno type

a

in

use

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show

all

the

geno types.

gametes

When

Ww

w

on F

genotypes

and

WW

2 Ww

ww

long

short

you

section ,

ww

have

try

page

read

this

ques tion

7c

169.

2

phenotypes long

F

phenotypic

ratio

3

wing

long

wing

:

1

wing

short

wing

wing

2

If

an

organism

concerned.

dominant,

alleles

are

If

if

has

the

two

identical

alleles

they

are

different

are

recessive

then

it

alleles

both

is

it

is

homozygous

dominant,

then

it

is

then

it

is

homozygous

heterozygous.

If

the

for

the

gene

homozygous

recessive.

males

and

If

the

two

females

in SUMMARY

the

as

first

the

generation

F

are

generation,

homozygous,

and

the

then

second

the

first

generation

generation

is

the

F

1

is

QUESTIONS

known

generation

2

1

Amongst

the

F

generation

¼

(or

25%)

are

homozygous

dominant;

Fruit

flies

crossed

with

with

grey

fruit

bodies

flies

are

with

2

½

(or

Since

50%)

the

are

heterozygous;

phenotypes

of

WW

¼

(or

and

25%)

Ww

are

are

homozygous

the

same,

¾

of

recessive.

the

F

ebony

flies

had

bodies.

grey

All

bodies.

the

offspring

When

these

2

have

a

long

ratio,

3

wings

long

and

wing:

¼

1

have

short

short

wings.

This

can

also

be

written

as

offspring

wing.

themselves,

the

next

bodies KEY

allele Follow

these

points

when

writing

genetic

Genotypes

of

organisms

have

two

alleles

as

they

are

two

sets

of

Genotypes

of

are

haploid

are

produced

gametes

(have

by

(sperm

and

eggs)

have

one

allele

as

the

rest

flies

had

in

ebony

alleles

Write

the

use

that

out

a

one

set

meiosis

grid

can

the

the

males

of

chromosomes).

which

show

at

This

is

because

were

grey

G

body

for

grey.

and

the

for

ebony

g

body,

for

draw

diagram

to

explain

result.

A

fruit

halves

the

chromosome

that

and

they

females

then

the

all

the

possible

will

in

first

make

combinations

that

you

crossed

show

of

clearly

first

a

black

offspring

3

a

grey

with

a

had

Define

body;

had

grey

black

the

body

fruit

generation

is

4

are

known

as

the

Suggest

good

F

why

F

the

and

homozygous,

and

fruit

animals

of

bodies

F

1

generation

fly

50%

bodies.

terms

heterozygous,

have.

the

with

number .

50%

sure

fly

they

fertilisation.

genotypes

and

homozygous,

to

occur

phenotypes

symbols

they

with

Always

for

genetic

was

If

the

chromosomes).

2

5

and

the

allele

this

4

of

diploid a

(have

3

¼

generation

among

diagrams.

the

2

crossed

POINTS Using

1

were

for

2

flies

make

studying

1

generation,

and

the

second

generation

is

the

F

generation.

genetics.

2

163

11.6

Inheritance

Mutations LEARNING

much

At

the

end

should

•

be

of

this

able

describe

affect

the

ways

genes

work.

In

some

cases,

there

is

so

OUTCOMES

the

topic

all.

you

change

In

others,

produced

to:

effects

to

the

the

but

it

gene

change

that

to

functions

it

the

in

a

does

DNA

not

is

code

quite

different

for

small

any

and

protein

a

at

protein

is

way.

of

Albinism mutations

•

define

People

codominance

in •

interpret

pedigree

•

state

causes

the

and

inheritance

of

this

these

sickle

cell

cannot

iris

of

make

the

eye.

the

pigment,

Several

melanin,

enzymes

are

which

needed

is

to

pigment

enzymes

and

that

it

is

is

a

the

mutation

cause

of

in

the

a

gene

that

condition.

codes

People

for

one

who

are

albinism albino

and

the

explain of

the

albinism

and

charts

make the

with

skin

are

homozygous

recessive,

aa.

People

who

are

homozygous

anaemia dominant,

the

or

functioning

they

risk

have

of

heterozygous,

enzyme

normal

sunburn,

normal

A

AA,

and

so

Aa,

melanin

pigmentation.

skin

cancer

have

and

People

is

the

that

produced.

with

damage

allele

to

This

albinism

the

eyes

codes

are

than

for

means

at

that

greater

people

with

pigmentation.

family

with

albinism

is

shown

in

this

pedigree

chart.

3

12

Figure

11.6.1

An

albino

Kuna

13

14

15

16

17

18

Indian

21 woman

The

and

Kuna

in

the

normally

Indians

Caribbean

highest

her

coast

live

of

pigmented

along

the

Panama.

percentage

of

19

20

eastern

They

people

child.

have

with

Key

the

albinism

Male

Female

world.

People

STUDY

very

chart

of

If

as

and

work

at

out

people

cannot

whether

is

carefully

many

you

be

homozygous

the

the

as

can.

A-

where

the

The

examples

The

recessive

you

have

albinism.

Look

carefully

at

the

key.

that

dash

allele

or

allele

we

is

have

not

looked

at

expressed

in

involve

the

alleles

that

phenotype

of

are

recessive.

individuals

or the

heterozygous

caused

by

genotype.

dominant

alleles,

Sometimes,

an

example

is

genetic

diseases

Huntington’s

can

disease

stands question

10

on

the

CD).

Other

examples

arise

when

neither

allele

a dominant,

and

both

alleles

are

expressed,

allele. a

164

family

can

is recessive

this

genotype

(see dominant

in

Codominance

be

a

people

sure

with

for

Several

genotypes

you

dominant

then

11.6.2

pedigree

absolutely

someone’s

heterozygous,

write

albinism

FOCUS

Figure

Look

with

mixture

of

the

effects

of

each

allele.

so

that

the

phenotype

is

This

condition

is

codominant

white

you

flowers.

cross

Flower

plants,

give

–

pink

capital

an

the

as

codominance

The

Four

colour

homozygous

flowered

as

known

alleles.

lower

case

and

plant

determined

red-flowered

offspring

intermediate

and

is

o’clock

are

all

colour.

letters

–

by

plants

pink.

the

can

one

with

Both

they

are

red

gene.

called

flowers

are

alleles

are

or

However,

homozygous

alleles

Codominant

instead

alleles

have

white-

expressed

are

usually

if

not

to

written

written

as

R

superscripts

of

the

letter

chosen

to

represent

the

gene,

e.g.

C

for

red

W

and

The

C

for

ABO

There

is

white

blood

more

(see

question

group

about

system

7di

is

a

on

page

human

codominance

in

169

for

example

an

of

example).

codominance.

Figure

12.1.

11.6.3

Codominance

these

flowers

o’clock

Sickle

People

of

a

cell

with

sickle.

sickle

The

blood

cells

and

found

is

including

the

have

a

to

to

of

carry

anaemia

of

normal

The

and

SCA

Asia

and

abnormal

is

red

North

who

forms

common

in

cells

in

among

for

and

South

is

common

Caribbean

people

and

with

or

the

the

used

USA.

in

Four

plant.

East

genotype

ss

heterozygous,

but

they

people

are

from

shape

the

red

Africa,

have

Ss,

They

the

have

rarely

resistant

areas

where Figure

malaria

the

America,

haemoglobin.

oxygen,

the

difficult

West

the

are

of

it

and

have

who

of

blood

makes

common

in

People

transport

allele

is

People

disorder.

with

have

haemoglobin

Caribbean.

the

visible

(SCA)

oxygen.

parts

problem

malaria.

cell

abnormal

in

the

symptoms

both

anaemia

is

of

to

As

genotype

be

both

Ss,

common,

forms

the

two

of

such

as

parts

haemoglobin

alleles

are

of

are

11.6.4

Red

the

blood

person

made

cells

with

from

sickle

a

cell

anaemia

by

codominant.

SUMMARY

QUESTIONS

LINK

1

You

can

genetic

find

out

diagram

about

in

the

answer

inheritance

to

question

of

8

SCA

on

by

the

writing

CD.

a

very

tests

exist

for

the

three

human

conditions

fair

described

in

This

means

that

it

is

possible

for

people

to

Use

the

know

if

the

mutant

allele

or

1

determine

the

sequence

of

amino

acids

in

the

If

the

protein

sequence

functions

Albinism

the

is

the

production

and

is

present

result

of

changes

as

in

a

different

of

a

mutation

skin

from

a

result

way,

or

of

mutation

Codominance

expressed

phenotype

of

to

pigment.

where

neither

two

being

heterozygous

organisms

distinguish

not

in

one

Albinism

of

is

at

the

a

and

Sickle

that

cell

mutant

give

anaemia

codes

the

for

allele

alleles

of

dominant

organisms

with

the

is

caused

haemoglobin.

are

sickle

active

cell

allele,

of

terms

genotype

and

heterozygous,

and

recessive

State

the

Kuna

woman

homozygous

dominant

genotype

and

of

her

the

child

all.

genes

recessive

for

Figure

two

trait

11.6.1.

possible

child’s

Suggest

genotypes

the

of

the

father.

or

is

a

gene

are

recessive.

a

both

State

the

The

trait,

in

a

tree

people

which

the

a

in

normal

who

gives

in

in

Figure

the

of

family

11.6.2.

What

are

is

the

probability

genotypes.

mutation

Both

genotypes

intermediate

homozygous

by

the

people

that

4

between

pairs

phenotype,

b

between

described

birth.

occurs

with

albino.

then

4

3

examples

and

in

2

an

being

each

3 protein.

or

of

not.

POINTS

Genes

skinned

following

gene

KEY

risks

they

the carry

health

this

here section.

the

Genetic

2 (DNA)

State

the

gene

allele

and

heterozygous

resistance

16

to

the

to

malaria.

the

and

next

17

albinism?

diagram

child

will

Draw

to

of

have

a

genetic

explain

your

answer.

165

11.7

Sex

determination

sex

Sex LEARNING

the

end

of

this

topic

•

be

able

describe

sex

the

based

determination

chromosomes

46

chromosomes

inheritance

on

the

X

and

of

chromosomes

can

chromosomes

that

chromosomes.

Y

X

what

term

sex

state

that

is

meant

by

be

which

these

matched

are

not

Females

chromosome

and

chromosomes explain

and

colour

sex

use

are.

In

pairs.

humans

In

there

females

all

46

in

a

have

Y

the

They

two

X

pairs.

known

The

determine

Males

as

chromosomes

chromosome.

gametes

into

are

and

diagram

the

sex

the

have

X

and

males

shows

of

two

Y

have

how

an

sex

individuals.

linkage

haemophilia

blindness

are

X

Y

and

Meiosis

Male

examples

XY

cell

X

linkage in

•

23

the

Diploid

of

you

in

together

alike.

Gametes:

•

sex

occur

to:

chromosomes

•

determine

you are

should

linkage

OUTCOMES

Your At

and

genetic

explain

sex

diagrams

testis

to

50%

of

an

chromosome,

X

sperm

have

X

linkage.

50%

XX 50%

have

a

female

Y

Y

Meiosis Female XX Diploid

in

X

All

X

Figure

11.7.2

The

are

All

egg

an

X

At

a

cells

Y -bearing

or

XY

numbers

The 11.7.1

An

X

and

a

Y

in

an

microscope

Y

12 000)

the

the

of

no t

the

fo rge

t

of

chrom osom es

haploid

num

to

ber

22

and

o ther

give

of

Y .

the

23.

There

Y

chromosomes

chromosome.

of

may

There

is

an

being

far

the

fuse

sperm

the

of

then

located

if

any

to

are

Males

on

is

of

linked

X.

with

equal

and

Half

sperm

determines

an

chance

or

genes

the

a

whether

sperm

Y

we

the

than

the

sperm

zygote

because

sperm

contain

chromosome.

X-bearing

of

male

Y -bearing

fewer

of

contain

either

female

One

testes

the

the

a

in

body

X

large

a

with

gene

on

the

the

that

embryo.

Y

If

develops

chromosome

them

in

one

are

two

recessive

chromosome

mutant

determining

of

recessive,

X

are

(Figure

other

or

inheriting

there

are

equal

11.7.2).

chromosomes

chromosome

it

is

is

not

stimulates

present,

or

if

it

female.

sex-linked.

with

many

allele

and

in

genes

then

of

a

colour

this

girls.

gene

features

controlling

the

the

chromosomes

than

are

with

copy

alleles

boys

examples

the

involved

have

have

common

T wo

do

genes

only

women

have

166

and

The

X

genes.

Most

have

sex

each

(egg

contai n

X

only

the

and

that

gam e tes

sperm )

X

of

linkage

chromosome

chrom osom es,

than

mutated,

Genes

show s

inherit ance

X

has

an

female.

half

child

X-bearing

fewer

nothing

Do

of

development

Sex

11.7 .2

egg

sperm.

the

an

have

electron

(×

TIP

Figu re

an

or

and

chromosome

far

has

EXAM

contain

and

eggs

chromosome

and viewed

male

chromosome

inheritance

male

chromosome

fertilisation,

XX

Figure

50%

XY

cell

ovary

is

why

effect

on

the

are

and

are

on

will

less

be

who

X

and

are

with

blood

X

gender.

clotting.

chromosomes;

seen.

affected

sex-linked

Women

blindness

vision

that

they

associated

Because

by

conditions

sex-

are

heterozygous

chromosome

haemophilia.

are

more

and

carriers.

Colour

blindness KEY

One

of

the

genes

on

the

X

chromosome

controls

the

ability

to

see

1 red

and

green

colours.

There

is

a

mutant

allele

of

this

gene

POINTS

Sex

is

sex does

not

produce

a

protein

necessary

for

colour

vision.

determined

The

allele

chromosomes,

so

any

girl

or

woman

who

is

heterozygous,

Rr,

the

has

X

and

Y .

is

Males recessive,

by

which

are

XY

and

females

normal

XX. colour

vision.

inherited

the

Males

allele

only

r

have

they

will

one

be

X

chromosome

so

if

they

have

colour-blind.

2

Sex-linked

on

the

Males

X

genes

located

chromosome.

only

have

chromosome,

alleles

are

are

one

so

more

expressed

in

X

mutant

likely

males

to

be

than

in

females.

3

Key

linked

Male

colour

11.7.3

What

If

can

you

you

cannot

something

then

you

11.7.4

with

that

be

the

colour-blind

who

familiar

both

boy

has

carriers

colour

have

who

of

such

sex-

as

blindness

Males

red–

and

can

never

carriers.

is

parents

normal

vision.

have

are

disorders,

haemophilia.

red-green

blindness

Note

see

must

red–green

Figure

see?

green

Female

People

Figure

Females

SUMMARY

QUESTIONS

colour

blindness.

1

The

is

R

Father’s

genotype

X

R

Y

×

X

r

X

Mother’s

ratio

about

females

genotype

of

R

Y

to

females

slightly

males

Draw

a

in

more

the

genetic

r

R

X

with

than

population.

Gametes

males

1:1

X

X +

diagram

Female

is

gametes

1:1

are

2

X

why

slightly

more

the

why

ratio

there

females.

X

R

X

show

suggest

r

R

X

R

to

and

R

R

X

r

X

What

is

woman

X

the

probability

who

is

a

of

carrier

a

of

Male

haemophilia

having

a

child

gametes R

Y

r

X

Y

X

Y

with

has R

Children’s

genotypes

X

R

R

X

X

r

R

X

X

the

phenotypes

Girl

with

Girl

who

Boy

X

with

Boy

with

has

colour

normal

vision,

vision

is

a

normal

but

colour

Draw

explain

3

Haemophilia

your

None

of

the

condition disease

in

which

the

blood

clots

very

slowly.

It

result

protein

A

of

a

that

carrier

of

Her

blood

It

rare

mutation

is

on

the

of

X

gene

that

chromosome.

haemophilia

clots

the

is

normally

a

woman

because

codes

The

who

she

diagram

answer .

conditions

also

for

a

mutant

has

the

has

blood

allele

are

you

between

that

is

a

sex-

tell

the

genetic

sex-linked

one

that

is

not?

clotting

is

recessive.

recessive

the

11.6

can

is

and a

in

How

difference

a

genetic

vision

linked.

is

a

blindness

described

Haemophilia

husband

Y

colour

carrier

her

clotting

red–green

to normal

if

blood

r

Y

time? Children’s

disease

normal

allele,

dominant

h.

allele,

H. LINK

is

have

her

to

for

woman

inherit

mother.

enough

a

to

the

to

mutant

Historically,

have

haemophiliac

have

may

allele

many

children.

man

haemophilia.

from

father

haemophiliac

Successful

have

her

a

This

with

is

because

as

men

treatment

daughter

is

well

did

now

the

as

not

she

would

from

live

available,

genotype

Now

long

so

to

a

try

test

question

your

9,

on

the

understanding

CD,

of

sex-linkage.

HH.

167

Unit

SECTION

1

Which

11

1:

of

formed

Multiple-choice

the

by

Practice

following

meiosis

in

exam

questions

describes

the

cells

4

humans?

A

short-haired

haired

One A

They

are

genetically

identical

and

cat.

of

B

They

They

are

genetically

They

are

In

a

identical

and

they

not

genetically

identical

and

they

are

not

genetically

identical

and

they

species

is

of

plant,

dominant

long-haired

Which

ratio

would

be

A

1

:

1

B

1

:

2

C

2

:

1

the

allele

for

blue

(b).

D

3

:

1

over

the

allele

for

T wo

There

blue-flowered

were

white-flowered

genotypes

crossed

hair.

with

cat.

of

short-haired

to

long-haired

cats

:

1

One

of

the

86

plants

of

the

chromosome.

BB

and

bb

B

BB

and

Bb

C

Bb

and

Bb

D

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Figure

168

1

gametes

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Figure

2

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169

12

Variation

12.1

and

Variation

Look LEARNING

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11.4.1)

during

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181

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inheritance

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11.4.2)

are

inherited

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parents

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fusion

of

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fertilisation STUDY

mutation

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FOCUS

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rays

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in

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to

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QUESTIONS

are The

mean

of

were

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in

Japan

in

1945

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the

nuclear

Chernobyl

in

the

Soviet

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power

station

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as

11.6

about

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cell

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least

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KEY

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differences

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chances

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occurring.

171

12.2

Natural

Natural LEARNING

selection

the

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12.2.1

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are

happened

Insects

and

increase

resistant

fungicides

to

used

to

insect

susceptible

in

number.

herbicides

to

to

control

pests

that

insecticides

The

and

fungal

them.

Figure

Industrial

melanism

–

Found

in

temperate

regions

of

the

12.2.2

Your

is

hemisphere,

there

are

two

forms

of

the

peppered

moth

view

–

a

very

and

a

melanic

(black)

variety.

Before

the

industrial

A

century),

few

were

to

melanic

easily

breed.

with

an

Lichens

variety

The

the

populations

individuals

spotted

eaten

Industrialisation

increase

died

was

and

cities,

remained

in

most

proportion

big

and

of

the

as

W ith

this

by

led

to

species

became

Air

soot

covered

the

form

Acts

in

in

in

Britain.

less

all

are

melanics

again

has

at

a

selective

advantage

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of

coal

the

speckled

populations

areas

the

it

around

still

speckled

numbers

no

of

new

selection

species

occur

have

to

change

some

aspect

of

Define

2

Explain

There

is

evolved.

the

term

the

natural

following

competition,

There

is

a

b

for

to

predation

and

disease.

terms:

overproduction,

struggle

competition,

Only

well-adapted

for

existence,

individuals

variation,

differential

survival

to

breed

and

pass

on

and genes

to

their

offspring.

success.

factors

that

limit

the

growth

of

populations

of

Antibiotic

resistance

in

animals industrial

melanism

plants. and

a

‘struggle

due

bacteria,

4

same

selection

4

and

between

existence’

their reproductive

the

the

QUESTIONS

survive

List

of

species.

3

3

variation

individuals

a

2 SUMMARY

1

POINTS

of

decreased.

examples

species;

as

agents.

survived

1

These

the

camoufl aged.

rural

the

of

act

environment.

industry,

and

that

they

KEY forms

birds

speckled.

burning

best

in

In

moths

that

revolution

because

never

the

soot.

melanic

and

but

the

increased

in

nearly

birds,

increase

and

Manchester

Clean

were

mutation

predatory

and

melanic

by

an

dioxide

conspicuous

such

rare.

sulfur

trees

of

appeared

to

speckled

selective

(19th

these

similar

predatory

variety

of

northern

Explain

the

natural

selection

State

the

roles

agent

of

in

of

humans

this

in

the

three

examples

topic.

selection

in

of

pesticide

among

insect

pathogens

each

case.

examples

resistance

pests,

and

of

plant

weeds,

natural

are

selection.

173

12.3

Species

and

their

formation

The LEARNING

are

At

the

end

should

be

of

this

able

topic

A

you

define

the

many

is

a

biodiversity

together

to:

terms

species

different

species

to

•

Caribbean

‘hot

spot’.

This

means

that

there

OUTCOMES

be

is

a

and

very

habitats

group

of

produce

little

occupied

related

fertile

variation,

by

many

organisms

offspring.

while

in

In

others,

different

that

are

some

species.

able

species

individuals

to

breed

there

may

appears

look

as

if

and they

belong

to

different

species.

Sometimes

two

species

look

very

speciation alike

•

use

examples

to

describe

and

Species speciation

without

by

occurs

physical

with

Caribbean

discuss

the

remain

cannot

breed

species

do

examples

extinction

distinct

together

attempt

do

not

of

12.3.1).

cannot

pair

testing

allows

whether

or

not.

in

which

new

ecological

is

the

of

is

the

result

of

a

a

male

donkey

female

produce

different,

horse.

fertile

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are

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of

that

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green

small

cross

seems

the

washed

beach

they

late

on

large

far

a

bodies

fetched.

1990s

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up

terrestrial

in

was

raft

Anguilla.

that

they

trees

which

and

as

not

mate

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produce

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sterile

offspring

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like

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mule

chromosomes,

to

look

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at

they

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gametes

the

enough

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formation

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to

be

genes

to

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test

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of

organisms

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and

same

species

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to

captivity.

species

of

arise:

new

from

species.

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geographical

are

two

ways

separation

or

in

from

separation.

same

species

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to

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water

the

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likely

to

of

time

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other

populations

through

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natural

and

belong

to

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offspring;

this

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means

species.

into

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islands

adapted

on

to

in

the

Caribbean

conditions

species.

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different

on

adaptive

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radiation

operating

in

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islands

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a

different

and

result

ways.

trees

Ecological

and

behavioural

separation

on can

occur

within

a

population

without

there

being

any

Scientists

came

iguanas

colonised

have

group

a

This

may

happen

because

some

individuals

occupy

of

a

habitat

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the

others

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become

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severe

thrown

into

barriers.

from

following

had

have

diversified

the

conditions

there

(Figure

behaviour.

Female

12.3.2).

It

from

a

change

in

the cichlid

fish

in

Lake

Victoria

in

Africa

select

males

of

sea. a

certain

(See

174

the

They

part Guadeloupe,

storm,

species

different

separation

mainland.

physical reckon

some

and

meiosis,

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new

different

able

Speciation a

of

KNOW? Anolis

in

different

cannot

offspring.

that

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from

individuals

and

significantly

ocean

apart.

cross

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do

barriers,

Environmental

mule

are

behavioural

geographical

of

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donkey

during

breed,

species

or

Populations

animals

individuals

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extremely

or

of

Geographical

idea

them

together;

scientists

is

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captivity,

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The

because

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It

Formation

YOU

tell

successfully.

breed

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together

organisms

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DID

to

species.

of

a

to

develop;

(Figure

species

A

eye

to

decide

12.3.1

expert

barriers

DNA

Figure

an

separation

geographical

use

takes

and

that

•

it

how

colour

question

and

15

on

this

the

has

CD.)

resulted

in

the

formation

of

new

species.

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Organisms

•

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Cuban

led

•

to

be

of

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the

–

in

seal

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which

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seal

•

by

to

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–

a

mountain

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•

rat

so

officially

ate

large

last

the

is

between

water

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of

in

of

for

in

the

them

a

1980s.

seals

the

to

time

Caribbean

between

1996.

breeding

Caribbean

from

of

the

the

considered

sighting

Bank

Jamaica

Other

and

species

of

12.3.3).

for

example,

owl

to

Atlantic

causing

Dominica

extinct

of

Costa

of

example:

extinction

extinction

extinct

for

the

extinction;

destroyed

mongoose

goats

about

half

the

else.

amphibian

in

lack

fishermen

species,

the

the

in

reported

(Figure

in

to

numbers

declared

infection

many

the

Seranilla

nowhere

become

–

to

Antiguan

Helena

chicken

Competition

the

found

of

has

on

led

reasons,

toad

century;

The

of

century;

golden

killed

1952

fungal

populations

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introduced

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species

variety

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the

endangered

probably

introduced

native

and

in

a

contributed

mid

was

are

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of

onwards.

was

Honduras.

•

the

for

deforestation

during

hunting

seal

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monk

–

extinction

competitors

monk

extinct

destruction

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monk

become

and

as

significant

species;

a

disease

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result

indigenous

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and

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is

in

affecting

the

the

Christmas

disease.

introduced

species,

this

has Figure

wiped

out

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island

the

Extinction

species

KEY

1

leads

to

become

a

loss

extinct,

in

biodiversity .

habitats

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become

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available

for

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all

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species

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to

species

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group

and

of

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evolved

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3

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geographical

ecological

living

4

in

organisms

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reasons

why

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that

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offspring.

2

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3

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in

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to

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fact

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over

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Earth;

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dinosaurs

ago

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being

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a

mainland

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islands.

of

life.

seven

the

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history

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65

the

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million

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years

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populations

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competition

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extinct.

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out

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on

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why

11.3

for

help

for

using

of

not

with

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examples.

lizards

cannot

does

the

local

Anolis

meiosis

meiosis

explanation

the

species

live

occur

occur

in

For

near

to

you.

produce

female

or

question).

evolution

of

different

species

of

Caribbean. Figure

4

parrot

Caribbean

species.

populations

speciation

behavioural

Explain

mules

Suggest

occur

of

from

two

QUESTIONS

revision

example,

formation

same

Habitat

SUMMARY

1

or

the

the

Lucian

are

FOCUS

extinctions

2

St

species

STUDY

is

The

parrot

fill.

POINTS

A

12.3.2

species.

list

of

the

factors

that

can

cause

species

to

become

extinct.

are

12.3.3

endangered:

one

–

the

T wo

the

Hawaiian

species

of

monk

Mediterranean

monk

seal

and

this

seal.

175

12.4

Artificial

People LEARNING

the

end

should

be

of

this

able

topic

Over

another

you

land

to:

define

the

races

term

(selective

use

examples

to

explain

•

explain

differs

selection

how

from

have

–

artificial

natural

races

extinct

endangered.

trying

to

selection

selection.

•

humans

•

animals

•

the

possible

of

useful

and

as

as

are

have

People

save

as

least

ten

livestock.

of

Across

livestock

selection

is

and

the

crop

one

thousand

world

there

plants

responsible

for

year

adapted

the

to

are

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to

local

considerable

occurred

to

species,

such

as

sheep,

goats,

cattle,

maize.

choose

or

a

plants

that

generation;

many

are

many

of

feature

(or

showing

show

the

trait)

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to

trait

are

culled,

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are

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are

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for

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selective

selection.

are

now

of

the

in

chosen

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eaten

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or

trait

not

for

breeding

are

used

used

continue

for

for

to

breed

the

breeding.

is

called

agent,

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individuals

survive

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have

not

decide

to

artificial

the

as

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breed

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and

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pass

on

to

it

as

is

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it

humans

is

with

improve

their

and

who

natural

which

alleles.

these races

been

replaced

in

many

places

by

commercial

sources such

as

modern

in

research

high-yielding

varieties

of

maize,

wheat

and

future Scientists

institutes

have

developed

these.

programmes.

Breeds

12.4.1

a

East

African

cattle

ticks

and

very

are

Zebu

resistant

(parasitic

eye

They

b

to

animals)

diseases.

can

survive

small

water.

176

at

from

selection:

process

rice.

Figure

have

offspring

varieties,

breeding

for

seed

KNOW?

land

become

varieties

and

generations.

Many

bred

Artificial

that

rice

artificial

This YOU

animals

kept

occurs

next

DID

kept

have

how In

artificial

and

farmers

breeding) wheat,

•

crops

time

artificial changes

selection

that

and

conditions.

•

grown

OUTCOMES years.

At

have

selection

thick

to

breeds.

cattle

from

Africa,

Mozambique)

prone

of

cattle

(South

have

on

amounts

Nguni

of

southern

Swaziland,

are

ticks

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and

have

of

skins

diseases

high

Africa

Zululand

tolerant

pigmented

adapted

calf

the

and

than

to

c

and

heat,

are

less

other

production.

local

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on

conditions

cattle

poor

from

quality

quantities

of

Uganda

food

water.

and

can

survive

limited

Crossing

varieties

yielding

existing

(Figure

Jersey

cattle,

hybridisation

For

some

can

and

features,

important

their

genes.

daughters.

go

varieties

12.4.1).

on

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can

be

passed

on

breeds

hip

of

joint

the

dog

to

the

a

cattle

males

are

is

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long

of

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from

the

properly

by

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from

in

a

the

they

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to

but

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as

EXAM

Do

contribute

performance

so

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food

by

of

our

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security.

very

few

pathogens

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genes.

with

e.g.

breed ing

being

gene tic

Many

failure

of

the

is

T able

12.4.1

T able

a

makes

in

to

more

Natural

and

the

wide

some

scale

forms

differences

artificial

of

of

to

is

from

(see

indivi dual s

natural

each

by

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usin g

risk

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to

other

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into

(see

over

Natural

Selective

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agent

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may

be

in

one

Humans,

factor

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important,

of

traits

QUESTIONS

selection

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and

farmers,

1

animal

Define

the

term

artificial

selection

breeders State

four

features

of

predation livestock

Type

of

12.5 ).

that

2 e.g.

cells

them.

Artificial

environment

very

the

one

selection

selection

total

one

from

time.

SUMMARY Feature

labora tory

trans fer

gene s

organi sm

anoth er

to

selection

selection

species

between

big

and

togeth er;

10.2).

artificial

the

a

infection

famine

and

aspects

which

gene tic

Artifi cial

them

proced ures

differ

susceptible

natural

similar

summarises

12.4.1

of

one

or

example,

them

possibility

is

change

for

uniform,

artifi cial

involv es

selectin g

lameness.

genetically

wheat,

between

selection

there

are

of

This

the

Differences

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plants

with

engine ering .

they

(or Many

confu se

selectio n

of

closely

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variation.

inbreeding,

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recessive

in

TIP

breeding.

dead.

reduction

leading

known

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of

is

new

from

selective

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superior

harmful

effects

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bred

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checking

selective

and

were

cattle.

show

after

result

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Jamaica

programme

not

collected

descendants

develop

by

features

in

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chosen

danger

This

suffer

and

followed

daughters

individuals.

to

is

Males

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combine

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siring

to

Hope

Adaptations

to

the

Useful

that

breeders

have

characteristics improved.

selected

conditions

in

the

for

humans,

e.g.

fast

3 environment

at

a

growth,

high

Most

herd particular

time

docile

of

All

traits

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or

a

few

traits,

herd

selected

disease

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slower

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in

a

Some

are

hornless.

of

The

decides

to

breed

more

resistance hornless

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cattle

horns.

e.g. farmer

traits

the

have

temperament

the Number

of

yield,

–

improvement

occur

in

this

several

cattle.

could

selective

be

Explain

achieved

how

by

breeding.

generations 4

A

plant

breeder

improve

KEY

Artificial

selection

performance

of

is

carried

livestock

out

and

by

crop

humans

to

improve

Humans

choose

individuals

tested

State

three

these

bean

that

features

show

the

to

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as

such

as

parents.

yield,

The

and

for

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and

those

that

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select

the

are

used

used

for

for

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breeding.

This

the

plants

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that

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generation.

for

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improved

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Describe

the

steps

the

desired

Others

would

follow

are to

not

features

offspring

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to

pinto

plants.

b

are

of

the

could

2

wants

yield

beans.

POINTS

a 1

the

improve

one

of

these

generations. features.

177

12.5

Genetic

DNA LEARNING

is

the

genetic

the

end

should

be

of

this

able

topic

develop

you

define

the

terms

engineering,

and

genetic

describe

(DNA)

Genetic

therapy

all

organisms.

genetic

in

the

to

conditions,

forensics

examine

ways

We

and

modify

have

exploited

treat

and

compare

relationships

species

our

cure

the

between

genetically,

genetic

genes

of

disorders,

different

them.

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can

species,

involves

be

such

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transferred

as

bacteria

genes

from

to

one

from

one

species

plants,

and

to

from

organism

a

to

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an

individual

genetic

is

used

one

new

species

to

another

individual

of

the

same

species.

This

can

be

to done

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of

develop

engineering

another.

testing

of engineering

for

to

genetic

gene

how

DNA

evidence

to

different •

of

tests

analyse

to:

species

•

material

OUTCOMES knowledge

At

technology

traits

by

simply

firing

a

gene

into

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cell,

or

the

gene

can

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placed

to into

a

vector

that

‘carries’

it

into

a

cell.

Examples

of

vectors

are

organisms viruses

•

use

examples

to

discuss

and

small

genetic

of

DNA

joining

up

DNA

from

DNA.

two

or

genetically

modified

All

cell

different

containing

and

other

used

from

slaughtered

Bacterium

DNA

produced

organisms

is

recombinant

called

DNA

have

to

pigs

for

be

treated

and

the

medicines

cattle,

meat

with

insulin

which

trade.

were

People

were

insulin with

gene

in

its

ring

of

DNA

worried

for

Insulin

of

gene

DNA

cut

by

Ring

an

of

of

DNA

bacterium

taken

and

out

the

people

or

made

open

by

an

diseases

insulin

scientists

with

diabetes

would

humans.

Figure inserted

exceed

identified

They

responsible

gene

animals

the

and

were

supply.

gene

In

that

that

at

risk

the

the

of

demand

1970s,

codes

transferred

the

piece

for

of

insulin

DNA

enzyme

laborator y

Insulin

from

split

in enzyme,

that

DNA

getting

in

plasmids.

(GM).

diabetics

obtained

out

more

Organisms

Insulin

with

as

engineering. been

Human

known

disadvantages recombinant

of

loops

the by

advantages

and

for

12.5.1

coding

shows

insulin

how

(gene)

this

is

to

done.

bacteria.

Bacteria

with

(splic

recombinant

DNA

divide

to

produce

bacteria.

insulin-producing

many

more

ed)

into

ring

another

of

bacterial

DNA

by

enzyme

the

nutrients

human

DNA

ring

with

insulin

it

is

taken

up

by

and

insulin.

conditions

Human

bacteria

they

insulin,

need

are

to

produced

given

produce

like

this,

gene

became in

The

available

in

1982.

bacterium

Many

into

other

medicines

human

modified

always

diseases

bacteria.

very

good

and

are

chemicals

made

However,

at

using

bacteria

producing

for

research

genetically

are

human

not

proteins,

Bacterium

multiplies

so

yeasts

and

certain

mammalian

cells

are

also

rapidly

modified

of

human

produces

•

a

• 12.5.1

This

process

was

carried

of

protein

human

178

insulin.

other

these

that

out

in

the

1970s

to

clots

for

industrial

production

substances.

medicines

prevents

are:

vaccines

bacteria

that

could

(see

thrombin

from

forming

for

6.4)

influenza

and

for

protection

from

make

cervical genetically-modified

and

ways

insulin

blood

Figure

similar

medicines

Examples

Bacteria

in

cancer

produce

•

factor

8

to

treat

haemophiliacs

(see

11.7).

Gene

therapy

–

genetic

engineering

is

also

used

in

gene

therapy. DID

This

involves

therapy

the

has

retina.

putting

been

There

a

dominant

used

are

to

treat

medical

allele

forms

trials

in

into

of

human

cells.

leukaemia

progress

to

and

use

YOU

KNOW?

Gene

a

disorder

gene

of

therapy

to

The

form

beta

of

GM

carotene

is

rice

that

called

makes

Golden

TM

treat

or

cure

other

genetic

disorders,

such

as

cystic

rice

fibrosis.

in Genetic

modification

Examples

cotton,

of

features

maize

and

–

that

many

have

tobacco,

crops

been

are

put

genetically

into

crops,

herbicide

resistance,

so

pest

as

•

drought

so

weed

insect

killers

can

be

used

while

the

crop

•

improved

so

pests

are

killed

when

they

eat

the

nutritional

of

rice

to

crops

will

qualities,

reduce

example

and

a

animals

sheep

type

of

and

the

fish

have

goats

that

grow

such

where

as

there

increasing

is

little

Genetic

engineering

process

of

number

of

children

the

vitamin

with

moving

also

that

grows

been

genetically

produce

very

human

testing

–

identify

mutations

genetic

diseases.

gene

in

(DNA)

people

from

and

putting

these

This

diseases.

can

T ests

help

are

can

think

reduce

also

GM

bacteria,

captive

modified,

proteins

in

for

useful

their

milk

animals

ago,

cheetahs

bottleneck’

zoos

they

Cheetahs

in

the

are

as

DNA

not

Social,

nearly

few

of

too

are

zoos

an

be

they

the

used

to

and

carried

might

number

ensure

wildlife

a

and

extinct.

to

breeding

genetically

ethical

endangered

became

survived

give

pair

•

are

some

Chemicals

larger

of

the

be

of

out

to

GM

crops

with

carriers

of

children

that

parks

of

species.

They

rise

and

different

available

quantities,

quantity

of

collected

a

in

to

went

the

does

not

About

for

There

lead

human

from

plasma

90 000

blood

or

is

tested

of

a

protein

Medicines,

the

e.g.

growing

insulin,

can

a

‘genetic

alive

to

today.

ensure

5

In

are

Food

crops

social,

ethical

implications

that

(DNA)

identifying

alleles

for

run

testing

the

genetic

in

and

of

is

used

mutant

disorders

families.

can

be

goat

in

produced

can

its

QUESTIONS

technology:

in

produce

milk

in

a

the

year

1

much

as

the

genetic

same

can

Define

and

be

following

terms:

engineering,

vector

plasmid

donations.

be

produced

in

large

quantities

to

meet

Describe

in

the

genetic

roles

of

enzymes

engineering.

demand.

have

better

resistance

to

pests,

so

not

as

Discuss

the

advantages

are

and

many disadvantages

pesticides

are

development.

engineering.

Genetic

for

3

•

in

implications

genetic

GM

livestock

features

to

2

•

as

years

that

quantities

example,

such

born

10 000

through

cheetahs

cheetahs

ecological

tiny

and

produce

breeding

similar .

implications

available

yeasts

cells

chemicals

SUMMARY

Here

organism

another.

insulin.

genetic inbreeding.

in

A

ecological between

one

it

blindness.

4 with

the

quickly.

tests

who

is

genetic

rainfall

3

Genetic

this

CD.

POINTS

mammalian

Domesticated

about

the

crop

2 content

on

is

material resistance,

more

soya,

1

resistance,

is

14

are:

growing

•

There

modified.

such

KEY

•

.

question

of

genetic

used. engineering.

•

Herbicide

resistance

could

pass

from

crops

to

weeds

so

that

they 4

become

‘superweeds’

that

farmers

cannot

a

What

is

the

breeding

•

GM

microbes

could

escape

from

laboratories

and

factories

GM

technology

gives

huge

advantage

to

the

companies

and

Discuss

market

GM

crops;

this

discriminates

against

who

cannot

afford

Knowledge

their

to

life

have

from

and

life

genetic

their

or

advantages

testing

for

of

human

them.

tests

children’s

health

the

small

genetic

•

individuals?

disadvantages

DNA

farmers

related

that and

develop

of

from

dangerous. b

•

cheetahs

and closely

become

danger

control.

helps

lives.

insurance,

if

It

people

could

that

make

also

decisions

affect

information

about

people’s

was

ability

sickle

disorders

cell

such

anaemia

Huntington’s

as

and

disorder.

disclosed.

179

Unit

SECTION

1

The

12

1:

best

Practice

Multiple-choice

definition

of

a

exam

questions

species

is

6

Humans

many A

a

group

of

closely

related

organisms

that

interbreed

have

changed

organisms.

the

Which

environment

of

the

of

following

is

organisms

not B

questions

to

give

an

example

of

natural

selection

influenced

fertile by

human

activities?

offspring

2

C

organisms

that

live

D

organisms

that

look

Which

is

not

an

variation

in

A

body

mass

B

foot

C

height

D

blood

in

the

same

A

adaptive

radiation

B

antibiotic

C

melanism

D

insecticide

of

Anolis

lizards

habitat

resistance

of

tuberculosis

bacteria

alike

example

of

in

peppered

moths

continuous resistance

in

mosquitoes

humans?

7

Which

of

the

following

may

result

in

speciation?

3

length

Jamaican

A

inbreeding

B

codominance

C

discontinuous

D

geographical

group

Hope

cattle

A

artificial

B

environmental

C

natural

were

developed

Human

genetic

reproductive

Transferring

improve

example

isolation

genes

its

from

specific

for

bacteria

nutritional

into

content

is

rice

an

gene

mutation

B

gene

therapy

C

genetic

9

gene

In

cells

and

would

tissues.

not

Which

make

a

of

suitable

the

target

A

epithelial

B

muscle

C

red

D

liver

cells

in

the

airways

cells

A

blood

genetic

captive

variation

breeding

cells

species

seeds

of

bird

programmes

species,

genetic

the

eaten

feeds

on

diameter

by

this

mean

diameter

beaks

of

of

of

seeds.

a

A

species.

the

large

scientist

Over

seeds

has

number

ten

of

years

the

increased.

The

for

variation

these

birds

have

also

increased

in

size.

is Which

maintained

cells

engineering

endangered

A

expressed

therapy?

measures

5

often

of

A

D

are

selection following

to

disorders

variation in

4

isolation

selection

8

D

variation

by

of

the

following

is

responsible

for

this?

by

breeding

between

distantly

individuals

B

hybridisation

C

inbreeding

between

between

species

closely

A

artificial

selection

B

ecological

C

geographical

D

natural

related

related

isolation

isolation

selection

individuals 10

D

180

storing

frozen

embryos

Which

about

of

the

gene

following

is

a

correct

statement

mutation?

A

It

is

the

only

B

It

is

always

C

It

is

very

D

It

changes

form

of

new

genetic

variation

harmful

common

the

number

of

chromosomes

SECTION

11

A

2:

student

species

of

Short

answer

questions

was

investigating

Ilex.

He

variation

measured

the

in

a

lengths

The

of

results

are

Colour

leaves

in

from

one

plant

and

recorded

the

shown

in

the

of

moths

Number

Number

released

recaught

results

millimetres:

pale,

60

60

64

65

65

82

82

83

83

84

65

67

71

73

75

87

88

89

90

93

75

77

77

77

79

93

93

95

100

108

speckled

black

c

i

Suggest

i

Calculate

the

range

the

of

lengths

the

number

of

shortest

longest

Divide

the

for

the

results.

likely

results

of

if

the

the

two

same

varieties

been

released

in

an

area

of

from

length.

range

36

moths

with

high

atmospheric

(1)

concentrations ii

100

by

length

woodland the

82

explanation

Suggest

had subtracting

an

100

(3)

ii

a

table.

30

in to

cla sses,

of

sulfur

dioxide

and

e.g. soot.

60–69 mm,

70–79 mm,

etc.

iii how

many

leaves

th ere

are

in

Explain

Use

the

resu lts

to

why

the

melanic

moth

is

not

each

a class.

(2)

Record

draw

different

species

from

the

speckled

a

moth. histogram

the

iii

to

show

th e

varia tion

leaves.

Explain

leaves

Total

(6)

why

is

an

variation

example

in

of

length

of

12

continuous

variation.

There

variety

speckled

wings

b

A

of

is

wings.

with

i

A

second

as

crossed

and

all

When

of

both

genetic

All

the

these

has

has

melanic

moths

of

moths

Moths

moths

the

groups

B,

AB

a

speckled

in

and

the

marks

ABO

O.

of

the

offspring

first

b

(4)

varieties

were

child

A

and

has

a

I

blood

diagram

B

,

I

O

and

group

to

I

,

for

gene,

show

the

draw

how

this

is

The

(5)

ABO

the

blood

of

group

system

dominance

genotypes

explain

why

this

Explain

why

the

is

of

and

the

is

an

codominance.

children

to

so.

(5)

had

wings.

both

groups

Each

group.

symbols,

the

genetic

Use

why:

cross

blood

possible.

crossed

explain

have

children.

blood

of

example

to

who

four

the

alleles

varieties.

offspring

of

A,

A

two

were

couple

have

Using

c

is ii

blood

are

different

black

had

A

B

pale,

variety.

the

offspring

diagrams

speckled

moth

variety

the

the

black-winged

were

Use

peppered

known

student

varieties

four

they

25

(3)

the

wings.

and

are

system;

a

One

(2)

in

present

an

example

ABO

of

blood

group

discontinuous

system

variation

in

(2) the

offspring

of

the

second

cross.

(4)

d Equal

numbers

of

both

varieties

were

State

is into

woodland

made

up

of

trees

three

ways

in

which

genetic

with

produced

among

offspring.

in

mottled

background.

trap

was

moths

as

lichens

used

to

making

After

catch

possible.

a

as

pale

two

many

(3)

bark

Total covered

variation

released

15

marks

coloured

weeks

of

a

moth

these

Further

and

on

practice

examples

the

questions

can

be

found

accompanying

CD.

181

13

How

to

13.1

take

Paper

Paper LEARNING

the

end

should

1

of

know

this

topic,

how

75

analyse

words

1

of

you

looking

and

key

That’s

not

for

is

some

questions

more

key

five

MCQs

must plant

Unit

9.

It

is

remember

quite

the

that

in

occur

leading

up

Writing

out

to

after

like

EXAM

one,

choose

notes

The

as

be

helps

with

In

section

from

on

how

across

in

the

the

to

answer

syllabus.

T est

yourself

multiple-choice

There

are

sections

many

on

the

CD.

test

(MCQs)

your

recall

are

is

genetic

the

parents

of

knowledge

draw

all

a

ts

if

write

and

your

you

put

answers

skill

your

and

at

answers

you

on

a

processes

occur

the

The

male

divides

3

A

4

The

which

the

pollen

nucleus

female

tube

by

a

carpel

after

mitosis.

male

nucleus

sequence

do

is

released

from

the

pollen

tube

and

fuses

gamete.

grows

down

travels

these

why

each

of

was

out

Read

the

Before

of

you

the

down

events

style

the

to

reach

pollen

the

micropyle.

tube.

occur?

→

last

A

1

2

3

4

B

2

4

1

3

C

3

4

2

1

D

2

1

3

4

you

the

(*)

are

sheet.

sure

to

of

your

right

by

the

sure

Do

that

Which

very

the

choice,

answer.

side

of

not

you

carefully

the

of

read

If

the

following

shade

than

first

look

not

and

four

of

come

to

the

If

you

answers.

be

sure

answer,

back

appropriate

one.

cause

the

again

sure

the

answer

changes

at

question

are

question

more

your

then

the

you

answer

shade

erase

and

to

it

space

change

you

put

later.

on

your

the

mind

thoroughly.

expiration

(breathing

occur?

the Diaphragm

Internal

muscle

muscles

intercostal

Volume

thorax

of

Pressure

thorax

A

contracts

contracts

decreases

increases

B

contracts

relaxes

increases

decreases

C

relaxes

relaxes

increases

decreases

D

relaxes

contracts

decreases

increases

If

to

genotypes

see

the

probabilities.

182

in

the

square

will

make

chosen

out)

children.

you

question

asterisk

2

the

with

possible

children,

within

righ t

starting

Punnett

the

four

2

make

ending

of

examination

possible

geno types

phenotypes

phenotypes

four

complete.

zygote

have

and

has

what

answ ers

diagram

the

the

inco rr ect.

3,

the

3,

question

decid ed

FOCUS

question

is

The

answer

any

this

first

have

your self

paren

o ther

STUDY

of

1

In

1

When

show

each

time.

part

an

you

thinking

sheet.

following

with

answ er

o thers

the

with

lasts

answer

dispersal.

co rrec t?

In

need

questions

Each

one.

answer

this.

ques tion

the

Paper

to

pollination

sequence

you

ask

woul d

of

The

seconds

of

TIP

When

which

In

seed

the

revision

questions

the

in

questions

Paper

pollination

your

you

75

difficult

sequence

1

of

questions.

have

reproduction

special

events

you

FOCUS

Flowering

in

if

topics

multiple-choice

comprehension.

to

means

ideas.

The

is

multiple-choice

long

advice

using

Multiple-choice

STUDY

60

which

to:

multiple-choice

questions

minutes,

question.

There

•

consists

exam

OUTCOMES for

At

the

Questions

like

information

key

try

word

to

out.

3

this

to

here

is

look

Figure

be

confusing

through.

It

expiration.

remember

Then

can

sift

what

for

the

13.1.1

is

because

best

Next

to

look

at

happens

to

row

matches

shows

that

the

there

read

these

the

the

column

four

items

your

inheritance

of

is

so

much

question

first.

headings

when

you

The

and

breathe

answer.

albinism

in

a

Key

family.

Male

The

family

is

probability

expecting

that

this

their

child

third

will

child.

inherit

What

is

–

normal

skin

colour

the Female

–

normal

Female

with

skin

colour

albinism?

albinism

?

A

0

%

(none)

B

25

%

(1

in

4)

C

50

%

(1

in

2)

D

100

Figure

This

Do

on

%

question

not

the

exam

(all)

requires

guess;

13.1.1

work

paper

it

you

out

so

to

work

logically

you

can

be

out

by

the

genotypes

writing

sure

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4b

187

Index

biological

A

abiotic

factors/biotic

factors,

ecology

biomass,

biotic

14–15

digested

small

food

aerobic

alleles

of

factors/abiotic

webs

19

numbers

factors,

16–17

ecology

respiration

(ATP)

28

inheritance

164

genetics

85

blood

vessels

cells

164–5

linkage

biodiversity

167

20

32–3

32

planting

33

coordination

91

glucose,

brain

162–3

tree

sex

32

pesticides

blood

bodies,

155

fertilisers

91

transport

74

pollution

inheritance

blindness,

commensalism,

138–9

immunity

74–5

colour

90–1

disease

45

codominance,

conservation

control

blood

68–9

cells

triphosphate

agriculture,

albinism,

birth

68–9

intestine

transport,

adenosine

food

14–15

absorption

active

control,

pyramids

animal

homeostasis

147

systems

irritability

86–7

reflexes

making

42–3

120–1

114–15

121

cross-pollination

142

120–1

D amnion,

sexual

reproduction

138–9

breathing

78–9

decomposers anaerobic

respiration

74–5

C animal

cells

38–9,

42,

food

carbon anti-diuretic

hormone

(ADH)

dioxide,

greenhouse

effect

resistance,

natural

waste

17,

19

management

24–5

107

30–1 antibiotic

webs

43

deficiency

diseases,

nutrition

72–3

selection

carnivores

16–17

deforestation,

human

activities

173

catalysts, apical

meristems,

plant

growth

cell arteries

division

artificial

selection

64–5

meiosis;

impact

mitosis

dengue

27

fever

reproduction

148,

149

147

transport

sexual

45

insulin

146,

147,

178

177

38–9,

42,

43

diet,

disease

147

134

bodies also

42–3

diffusion

reproduction

diffusion mitosis

146,

176–7

selection

animal asexual

diabetes

38–45

active natural

see

see

86–7

cells

vs

enzymes

133

156–7,

44

cells

44

161

leaf

structure

52–3

gas

exchange

76–7

assimilation

microbes digested

food

40–1

organisation liver

osmosis intestine

nutrition

48,

digestive

system

38–9,

structure

B

bacteria

diet

Benedict’s

testing

substances

waste

62–3

conservation

10–11

photosynthesis

16–17

chromosome

16–17

chromosomes

food

webs

diploid

organisms

mutualism

21

symbiosis

75

10–11

substances

52,

55

mutation

171

causes

diet

154–61

154,

154,

system,

155

146–7

fever

malaria

86–9

147

plants

effect

150

34,

148,

mosquitoes

150–1

149

148–9

149

sexually

greenhouse

149

147

HIV/AIDS

biodiversity

148,

147

gonorrhoea

155

humans

146

146–7

exercise

166

organisms,

change,

30–1

154,

91

diabetes

10–11

climate

chromosomes

146–51

dengue

50

determination

classifying

number,

categories

52–3

number

circulatory

12–13

diploid

63

63

blood

56–7

50,

number

haploid

sex

20

20

teeth

control

structure

photosynthesis

18–19

62–7

62–7

functions

30–1

52–3

nutrition

flow

habitats

food

enzymes

disease

structure

chains

sampling

effect

chlorophyll

leaf

14–15

parasitism

digestion

44–5

chloroplasts

20

32–3

identifying

69

63

155

food

energy

bile

membranes

testing,

mineral

organisms

commensalism

68–9

assimilation

(chlorofluorocarbons),

leaf

24–5

10–23

classifying

52–3

60–1

63

waste,

management

cell

greenhouse

chemical

system

biodegradable

ecology

food

60–1

digestive

biodiversity

CFCs

70–1

solution,

42–3,

42–3

38–9

transport,

40

balanced

absorption

49

specialised

188

43

44–5

68–9

plant autotrophic

biogas

84–5

69

small

bile,

transport

69

(STIs)

transmitted

150–1

infections

Index

sickle

cell

anaemia

treatment

vectors

yellow

DNA

(SCA)

food

energy

148–9

fever

154–5,

148,

food

149

genetic

testing

genetic

179

127

178

food

non-medicinal

solution

testing

greenhouse

effect,

climate

change

30–1

60–1

growth

60–1

132–3

meristems

germination

lateral

webs

133

132–3

meristems

measuring

18–19

17,

60–1

74–5

150

apical

decomposers

testing

50

gonorrhoea

60–1

biodiversity

127

testing

60–1

sucrose

126

respiration

16–17

nutrition

chemical

starch

technology

medicinal

also

Benedict’s

178–9

126–7

abuse

flow

substances

photosynthesis

16–17

substances

see

156

technology

drug

food

chains

biodiversity

genetic

drugs

164–5

146–7

133

133

19

H predators/prey

18–19

E

habitats forest

resources,

human

activities

ecology

conservation impact

abiotic

factors/biotic

factors

restoration fungi

biodiversity

effectors,

egestion

sampling

energy

irritability

reproduction

pyramids

of

138–9

numbers

16–17

16–17

chains

16–17

factors

62–7

how

excretion

exercise,

to

the

102–7

species

175

122–5

genetic

123

124–5

HIV/AIDS

179

(GM),

genetic

blood

179

technology

therapy

growth

178–9

water

179

162–3

34

testing

(GM)

179

human

179

fish

stocks

resources

178

genetic

technology

128–9

106

genetics

activities

deforestation

178

147

control

control

homozygous,

genetic

testing,

glucose

temperature

modification

genetics

48–9

genetics

150–1

population

162–3

impact

26–7

27

26

26–7

hydroponics,

plant

mineral

nutrition

56–7

179

125

154,

homeostasis

genetic

genetic

124

reflex

171

modification

medicines

nutrition

heterozygous,

technology

167

16–17

heterotrophic

genetic

linkage

chromosomes

88–9

herbivores

154–5

insulin

glaucoma

pupil

therapy,

gene

147

accommodation

defects

gene

genetic

182–7

heart

77

mutation

sex

number,

155

76–7

50,

haploid

28–9

76–9

technology

take

disease

extinction,

eye

66–7

64–5

pollution

134–5

78–9

gene

genes

affecting

properties

exam,

exchange

plants

64–5

digestion

reproduction

disposal,

diffusion

enzymes

catalysts

garbage

sexual

breathing

biodiversity

14–15

haemophilia,

gas

33

12–13

34–5

G

gametes,

sexual

growth

soil

115

flow

food

population

29

103

embryo,

energy,

pollution

methods

40

14–15 future,

ecotourism,

32–3

27

14–15

162–7

I see

also

inheritance

F

identifying alleles

162–3

142–3

immunity heterozygous

humans

implantation,

conservation

stocks,

human

135,

activities

industry,

sex

determination

sex

linkage

see

genetics

codominance 132–3,

142,

sickle eye

defect

164–5

143

142–3

reproduction

164

162–3

140–2

glaucoma,

sexual

genetics

albinism

germination

foetus,

also

166–7

142–3

dispersal

28

164–5

166

140–3

genotypes,

seed

pollution

inheritance

pollination

reproduction

162–3

26

fertilisation

sexual

136–9

164–5

impact phenotypes

flowers

92–3

162–3

32 inheritance

fish

91,

162–3

138–9 homozygous

fertilisers,

biodiversity

10–11 genotypes

flowers

organisms,

162–3

fertilisation

cell

anaemia

(SCA)

164–5

124

138–9

insulin glucose

follicle

stimulating

hormone

(FSH),

diabetes blood

menstrual

cycle

glucose,

136–7

homeostasis

genetic conversion

146,

147,

178

147

technology

178

50

189

Index

integrated

waste

invertebrate

management

responses,

25

irritability

mosquitoes,

movement

animals/plants

118–19

joints/muscles

irritability

coordination

invertebrate

plant

disease

responses

receptors

skeleton

114–15

responses

118–19

114–17

muscles,

115

108–9

155,

reproduction

conservation

genetics

134

32

162–3

phloem

storage

110–11

164–7

98–9

translocation

photosynthesis

mutation

mutation

sexual

phenotypes,

110–11

108–9

chromosome

gene

penis,

pesticides,

movement

mutation

148–9

108–11

171

chlorophyll

171

98–9

50–5

50,

chloroplasts

52,

55

50

J lung

joints,

movement

cancer

81

glucose

50

110–11 natural

selection

sickle

cell

types

171

172–3

anaemia

leaf

(SCA)

165

structure

light

52–3

54–5

K

keys,

classifying

organisms

mutualism, kidneys

starch

54

10–11 biodiversity

21

placenta,

sexual

reproduction

138–9

104–7

nephrons

plant

cells

38–9,

plant

responses,

42–3,

52–3

104–7 N

pressure

filtration

irritability

114–17

106 natural

selection

172–3 plants,

antibiotic

resistance

disease

149

173 pollination,

flowers

140–2

L vs

artificial

selection

177 pollution

lateral

meristems,

plant

growth

133 mutation

172–3 see

leaf

structure

28–9

also

waste

struggle

for

existence

172–3 agriculture

chlorophyll

28

52–3 variation

172–3 ecotourism

chloroplasts

kidneys

104–7 garbage

photosynthesis

28

52–3 nicotine,

smoking

80–1 marine

to

environment

29

6–9 nitrate

ions,

plant

mineral

nutrition population

ligaments,

28–9

120–1 industry

how

disposal

52–3 nerves

stomata

29

52–3 nephrons,

learn,

management

52–3

movement

growth

26,

34–5

110–11 56–7 challenges

light,

photosynthesis

non-biodegradable

waste,

assimilation

lung

cancer

affecting

69 management

24–5 HIV/AIDS

drugs

34

127 projections

hormone

(LH),

35

menstrual nutrients,

balanced

diet

70–1 predators/prey,

cycle

see

also

filtration,

progesterone,

autotrophic magnesium

ions,

plant

diet

134,

diseases

protists

nutrition

drugs

technology

mineral

biomass

and

50–5

nutrition

56–7

Q

178

saprophytic

nutrition

49

quadrats,

sampling

habitats

12–13

158–61

types mitosis

numbers,

16–17

126

genetic

155,

of

energy

29

plant medicines,

135

72–3

photosynthesis medicinal

136–7

41

pyramids

pollution

cycle

reproduction

48–9

72–3

environment,

sexual

72–3

149

malnutrition

menstrual

gland,

70–1

56–7

heterotrophic malnutrition

vs

18–19

106

49 prostate

deficiency 148,

nutrition

mineral

balanced nutrition

kidneys

food…

M

meiosis

webs

48–57 pressure

marine

food

136–7 nutrition

malaria

35

34–5

81 non-medicinal

luteinising

solutions

waste factors

liver,

and

54–5

48–9

161 R

variation

160–1 O

menstrual

cycle

receptors,

obesity metabolism

recycling,

73

greenhouse

effect

cells

menstrual

cycle

136–7

16–17

cells

coordination

44–5

pupil

reflex

121

125

nutrition ovaries

chlorophyll

reproduction

humans

cycle

136–7

asexual

reproduction;

sexual

70–1 sexual

plants

see

56–7 menstrual

reproduction

135

reproduction

56–7 ovulation,

mitosis

24–5

reflexes

40–1 osmosis,

mineral

115

management

30–1 omnivores

microbes,

waste

102–3 oestrogen,

methane,

irritability

136–7

155,

menstrual

cycle

136–7

resources,

human

activities

impact

156–7 26–7

vs

meiosis

161 P respiration

zygotes

parasitism,

biodiversity

20 restoration

190

74–5

138 methods,

habitats

33

Index

small

S

sampling

habitats,

saprophytic

biodiversity

nutrition

intestine,

smoking

49

absorption/

assimilation

12–13

menstrual

68–9

sexual

cycle

136–7

reproduction

135

80–1

V seed

dispersal,

flowers

soil,

142–3

habitats

14–15

vaccination selection

see

artificial

selection;

vagina, natural

extinction

selection

sexual

breeding

species

176–7

formation

174–5

fluid,

sexual

food

reproduction

substances

testing

photosynthesis

135

50,

determination,

sex

linkage,

genetics

166

stomata

disease

reproduction

animals/plants

134–5

86–7

99

viruses see

also

asexual

phloem

reproduction

41

98–9

vitamins amnion

birth

struggle

138–9

control

70

storage

166–7

veins sexual

134

148–9

51–3

vegetarians genetics

172–3

reproduction

54

vectors, sex

selection

60–1

sexual 134,

160–1

starch

142

natural seminal

135

170–1

meiosis self-pollination

reproduction

175

variation selective

93

species

for

existence,

selection

138–9

70–2

natural

172–3 W

embryo

fertilisation

foetus

sucrose,

138–9

survival

138–9

food

testing

60–1 waste

(excretion)

waste

management

biodiversity

24–5

20 see

gametes

102–7

114–15

symbiosis,

138–9

substances

also

pollution

134–5 biodegradable

waste/non-

T implantation

135,

136–9 biodegradable teeth

meiosis

decomposers temperature ovaries

24–5

24–5

control

135 integrated homeostasis

penis

waste

63

158–61

25

128–9

134 recycling human

placenta

skin

128–9

138–9 water tendons,

prostate

gland

134,

fluid

134,

movement

control,

homeostasis

106

110–11

135

testes, seminal

24–5

sexual

reproduction

134,

135

135 X translocation,

testes

134,

phloem

98–9

135 xylem, transpiration

uterus

factors vagina

affecting

94–5

96–7

135

Y

plant variation

adaptations

97

134

yellow

transport zygotes

134,

138,

transmitted

body,

sexual

reproduction

136,

84–101

139

137

animals/plants sexually

transpiration

94–7

135

infections

84–5

(STIs)

yellow

blood

fever

148,

149

85

150–1

cell sickle

cell

anaemia

(SCA),

membranes

44–5

Z

inheritance

circulatory

system

86–9

zygotes

164–5

diffusion

84–5

flowers

skeleton

humans functions

movement

human

sexual

108–9

tree

skin,

86–93

planting,

conservation

142

reproduction

134,

138,

139

33

108–9

128–9 U

functions

128 urinary

temperature

control

system

104–7

128–9 uterus

191

Acknowledgements

The

authors

0.1.1

and

Jacques

Science

Photo

School;

1.5.2

1.6.3

1.6.6c

Images/Kim

2.5.2

Dr

Cattlin/Alamy;

Morley

Read/Science

Photo

Photo

Library;

1.6.1

Photo

Library;

2.1.1

1.2.1

Stuart

Wesson

Library;

1.6.6b

1.6.5

Dr

iStockphoto;

2.1.2

Getty

Images/Bernhard

Nigel

Cattlin/Alamy;

Photo

Unlimited,

Fosbery;

4.1.2

4.2.1

Nigel

4.5.1

Dr

5.10.2

Photo

Photo

Richard

6.5.2

Caro/Alamy;

6.6.3

Getty/Visuals

Library;

Imaging

Shutterstock;

Richard

9.6.3

Fotolia;

Awareness

10.2.2

Fotolia;

Library;

Adrian

Solvin

11.6.3

Dr

11.7.1

Science

Alamy;

12.3.1

question

Figure

effort

overlooked

Thanks

are

has

also

been

Wellcome

Jim

Marie

W .

Dr

12.1.1

12.3.2a

12.4.1b

Inc./Science

Unlimited,

Ian

Dave

adapted

John

from

Photo

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Luttick,

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Library;

Leroy,

Bill

12.3.2b

Allen’s

Coordinated

CD:

9.6.1

);

EAG,

Visual

Images;

Gainey/

Fotolia;

Environmental

10.2.1

Fotolia;

11.2.1

Shutterstock;

Written

SL/Alamy;

Biocosmos/Science

12.2.2b

Wegner/Alamy;

Further

Hill

iStockphoto;

Unlimited/Science

11.2.4

&

Getty/

Clouds

Tim

9.6.4

iStockphoto;

Coster/Alamy;

Petra

Girls’

Visuals

Library;

11.6.1

Francis

8.3.3

Photo

Fosbery;

7.4.2

8.1.6

AFP/Getty

9.6.7

Science

Syred/Science

iStockphoto;

11.1.4

Photo

iStockphoto.

James

Library;

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Reschke;

Unlimited/

Library;

Library;

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Richard

Library;

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Photo

Gelderblom,

12.2.2a

Watts/Alamy;

Photo

Photo

London;

Photo

Fotolia;

Hans

11.6.4

Shaw/Alamy;

Shutterstock;

and

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And

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www.eagantigua.org

Barksdale/AGSTOCKUSA/Science

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Moore,

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Photo

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Photo

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6.3.1

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Lambert

Unlimited,

Bob

Jeremy

Lamborn/Alamy;

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6.8.4

Daniel

Dr

Library;

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Randy

Photo

Perennou/Science

);

Photo

Cattlin/Science

(website:

Library;

Steve

Library;

Unlimited/Corbis;

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Library; 5.6.1

5.9.1

Richard

4.3.2

Photo

Werner/Visuals

Examinations;

Inc.;

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Unlimited/Science

Syred/Science

Production/

Group

Koster/Corbis;

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Wesson

Photo

Bill

12.3.3

questions,

Unit

Library;

Coster

IN/

Fotolia;

8,

School.

Science:

Higher

Biology

by

R.

Fosbery

1996).

made

to

8.7.1

Nigel

8.1.5

5.1.1

Photo

Donald

Inc.;

Dimijian/Science

Associates/Science

Library;

Library;

6.8.2

Unlimited,

King-Holmes/ICRF/Science

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publisher

due

&

and

Science/Science

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Awareness

Photo

International

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Library;

iStockphoto;

Mike

Dr

Unlimited,

Cattlin/Visuals

Biophoto

Photo

Hossler ,

Fosbery;

Lisa

&

Chillmaid/Science

Power

iStockphoto;

Mona

Fosbery;

Calentine/Visuals

iStockphoto;

the

of

www.eagantigua.org

11.2.2

been

6.6.4

Richard

Eye

8.1.3

Nuridsany

James

Fred

Wagner/Visuals

7.1.3

iStockphoto;

Amanda

(Pearson

6.7.4

Berrod,

Richard

F .

5.7.3

Medimage/Science

MedicImage/Alamy;

9.5.4

Claude

Photo

has

Ken

Thierry

(website:

Laurence

7.3.1

7.3.2

Zankl/Visuals

McLean

Dr

Harvey;

Environmental

iStockphoto;

13

Fosbery;

Carol

Herve

3.1.5

Science/Science

Nigel

Library;

Getty

iStockphoto;

Gregory

Library/Alamy;

5.3.1

Hall/Science

Dr

Cambridge

Inc./Scientifica;

Shutterstock;

10.3.1

Robert

Martyn

David

4.5.4

4.3.1

of

Unlimited/Science

SA/Alamy;

Associates/Science

Couchman,

6.8.3

8.1.7

11.1.2

11.5.1

Prof.

Biophoto

Ian

Richard

Davies/Alamy;

12.4.1a

6.4.2

8.6.4

9.6.6

Group

5.8.5

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Eye

Photo

4.1.5

Photo

Photo

3.1.1

Inc.;

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iStockphoto;

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iStockphoto;

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iStockphoto;

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Science

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van

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iStockphoto;

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Unlimited,

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Dr

Library;

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Photo

6.8.5

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Michael

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Cattlin/Visuals

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Unlimited/Corbis;

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Wim

1.2.2

Luttick,

Limberger;

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Chapman/Visuals

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Fosbery;

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Photo

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iStockphoto;

Science

Richard

Kessel

Library;

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Fosbery;

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Bhargava/Corbis;

Shutterstock;

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Richard

Dr

iStockphoto;

Images/Nigel

Photo

Richard

Amit

3.1.4

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Photo

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Science

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Inc.;

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reproduce

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John

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ISM/Science

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permission

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P re s s

to

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