Oxford Revise AQA GCSE Combined Science Foundation | Chapter B17 answers

B17: Organising an ecosystem

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Extra information

Mark

AO / Specification reference

01.1

14

1

AO2

4.7.2.1

MS 2f

01.2

\(
\frac{96}{8}
\)

12

1

1

AO2

4.7.2.1

MS 2f, 2b

01.3

trampled area / shaded area / many other species present / random variation

Prevented daisies establishing / growing / competition from other species

1

1

AO3

4.7.2.1

02.1

presence of other plant species

1

AO2

4.7.2.1

02.2

quadrat

1

AO2

4.7.2.1

02.3

D

A

C

E

B

1 mark for one correct

2 marks for two correct

3 marks for three correct

4 marks for all correct

4

AO2

4.7.2.1

03.1

Any six from:

  • Burning / combustion
  • Converting carbon in fuel into carbon dioxide
  • Photosynthesis
  • Converting atmospheric carbon dioxide into carbon compounds in plants
  • Respiration
  • Converting carbon from food sources into (atmospheric) carbon dioxide
  • Feeding
  • Carbon passed from organism to organism
  • decay / decomposition of dead organisms
  • releases carbon dioxide into the atmosphere.

Allow six marks for an appropriately labelled diagram

6

AO1

4.7.2.2

03.2

Increased rate of combustion (of fossil fuels)

Increases atmospheric CO2 concentration

Deforestation

Reduces rate of CO2 removal from atmosphere

1

1

1

1

AO1

4.7.2.2

04.1

grass

1

AO2

4.7.2.1

04.2

sparrow / hawk

1

AO2

4.7.2.1

04.3

slug / sparrow

1

AO2

4.7.2.1

04.4

hawk

1

AO2

4.7.2.1

05.1

dies

leaves

droppings

decomposers

nutrients

1

1

1

1

1

AO1

4.7.2.2

05.2

microorganisms

1

AO1

4.7.2.2

05.3

make nutrients available for other organisms

prevent build-up of dead organisms

1

1

AO1

4.7.2.2

05.4

carbon / nitrogen

1

AO1

4.7.2.2

06.1

Aquatic plant

1

AO2

4.7.2.1

06.2

Seal

1

AO2

4.7.2.1

06.3

Light / sun

1

AO1

4.7.2.1

06.4

Crab / octopus

1

AO2

4.7.2.1

06.5

Any one from:

  • Camouflage – so organism is harder to be seen
  • Named defence mechanism, e.g. warning colouration – to mimic poisonous plants
  • Hard shell (crab) – more difficult to catch

Allow 1 mark for a sensible adaptation and 1 mark for linked explanation

2

AO2

4.7.2.1

4.7.1.4

06.6

Fewer seals / no seal to eat the octopuses

so octopus population would increase

so number of crabs would go down / more crabs would be eaten

1

1

1

AO3

4.7.2.1

07.1

evaporation – water changes from a liquid into a gas

condensation – water changes from a gas into a liquid

precipitation – water falling from the atmosphere to the Earth

transpiration – loss of water vapour from plants

1 mark for one correct

2 marks for two correct

3 marks for all correct

3

AO1

4.7.2.2

07.2

Sun

1

AO1

4.7.2.2

07.3

For photosynthesis / to support plant cells / as a habitat / to sustain source of food

1

AO1

4.7.2.2

08.1

1933

1

AO2

4.7.2.1

Ms4a

08.2

56 000

Accept 55 000–58 000

1

AO2

4.7.2.1

Ms4a

08.3

3

2

1

1 mark for one correct

2 marks for all correct

2

AO2

4.7.2.1

08.4

hares – (drop for a couple of years) then start to rise again

lynx – (Rise then) fall

1

1

AO3

4.7.2.1

09.1

A – death

B – feeding / consuming

C – respiration

1

1

1

AO2

4.7.2.2

09.2

Carbon dioxide + water ➔ glucose + oxygen

1

AO1

4.7.2.2

4.4.1.1

09.3

oceans / lakes / rivers / rocks

1

AO1

4.7.2.2

09.4

Any two from:

  • break down dead organisms / organic matter
  • releasing carbon dioxide into the atmosphere as microorganisms respire
  • prevent build-up of dead bodies

2

AO1

4.7.2.2

10.1

Provides a constant supply of water for animals to survive

1

AO1

4.7.2.2

10.2

Photosynthesis

1

AO1

4.7.2.2

10.3

Any two from:

  • carbon dioxide levels – needed for photosynthesis
  • light intensity – needed for photosynthesis
  • soil pH – optimum pH needed for healthy roots
  • soil mineral content – need sufficient minerals in the soil for plant growth
  • temperature – plant enzymes for photosynthesis work at optimum temperatures

1 mark for abiotic factor

1 mark for linked explanation

Accept any other sensible suggestions

4

AO1

4.7.1.1

10.4

Clockwise from top right:

Precipitation

Transpiration

Evaporation

Condensation

1

1

1

1

AO1

4.7.2.2

11.1

Eye colour – inherited from parents

Tattoo – not inherited from parents

Measles infection – not inherited from parents

1

1

1

AO1

4.6.2.1

11.2

Any four from:

  • You get half your genetic material from either parent
  • Passed on through gametes / egg and sperm
  • Join together during fertilisation
  • Combination of genes / genetic material a child inherits depends on which gametes join
  • Each sibling has a different combination of genes / genetic material

4

AO1

4.6.2.1

11.3

A change in the order of DNA bases/DNA

1

AO1

4.6.2.1

11.4

Advantage – disease resistance / pest resistance / antibiotic resistance / accept other appropriate suggestion

Disadvantage – disease / cancer / accept other appropriate suggestion

1

1

AO3

4.6.2.1

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