AQA GCSE Combined Science: Trilogy Biology Paper 2 (Higher), 2020: Question 7

8 marks · Standard Demand difficulty · Extended Answer

Describe reasons for deforestation and its environmental effects, and explain in what ways calling forests 'the lungs of the planet' is correct and incorrect.

Practise this question

Question

The image shows a GCSE Biology exam page headed 'Human activities affect the environment' with three written-response parts numbered 07.1, 07.2 and 07.3. Question 07.1 asks students to describe reasons why deforestation takes place and the effects deforestation has on the environment for 6 marks, followed by many blank answer lines. Lower on the page, a prompt says forests have been called 'The lungs of the planet', then 07.2 asks for one way this statement can be considered correct for 1 mark, and 07.3 states 'Trees do not have lungs' and asks for one other way the statement is incorrect for 1 mark, each with blank lines for responses.
Question text

07 Human activities affect the environment.

07.1 Describe the reasons why deforestation takes place and the effects deforestation has

on the environment.

[6 marks]

Forests have been called:

‘The lungs of the planet.’

07.2 Describe one way forests being called ‘The lungs of the planet’ can be considered to

be a correct statement.

[1 mark]

07.3 Trees do not have lungs.

Describe one other way forests being called ‘The lungs of the planet’ is

an incorrect statement.

[1 mark]

Mark scheme

Show the mark scheme The mark scheme is a table with rows for questions 07.1 to 07.3 and columns for answers, extra information, mark and specification reference. For 07.1, a level-of-response scheme awards 1 to 3 marks for simple relevant facts and 4 to 6 marks for a detailed accurate account, with indicative content including reasons for deforestation such as clearing land for cattle, crops, mining, biofuels, palm oil, timber, paper and farming, and effects such as reduced photosynthesis, carbon dioxide release from decay or burning, greenhouse effect, global warming, habitat loss, reduced biodiversity and soil erosion. For 07.2, 1 mark is awarded for the idea that forests involve gas exchange with the atmosphere; for 07.3, 1 mark is awarded for explaining that forests use carbon dioxide and release oxygen whereas lungs use oxygen and release carbon dioxide, with extra creditworthy detail mentioning diffusion in leaves versus ventilation or breathing in animals.

AO /

Question Answers Extra information Mark

Spec. Ref.

07.1 Level 2: Scientifically relevant facts, events or processes are 4–6 AO1

identified and given in detail to form an accurate account. 4.7.3.4

4.7.3.5

Level 1: Facts, events or processes are identified and simply 1–3 4.7.1.2

stated but their relevance is not clear. 4.7.3.6

4.7.2.2

No relevant content 0

Indicative content

Reasons

• tropical rainforests cleared for land

• that land used to raise cattle, plant rice or plant crops such as

coffee

• land cleared for mining

• that land used to grow biofuels or palm oil

• (temperate) forests cut down for wood for building / paper

• (temperate) forests cleared for farming (wheat / sheep)

Effects

• less trees to take in carbon dioxide for photosynthesis

• decay by microorganisms respiring releases carbon dioxide

• burning waste wood releases carbon dioxide

• build-up of carbon dioxide in atmosphere leads to greenhouse

effect

• build-up of carbon dioxide in atmosphere leads to global warming

• consequences of global warming

• habitat loss

• leading to reduced biodiversity

• leading to soil erosion

Must consider both reasons and effects for Level 2.

07.2 (forests) involve gas exchange 1 AO1

with the atmosphere – OMBINED SCIENCE: TRILOGY – – 4.4.1.2

07.3 (in forests) carbon dioxide is allow gas exchange occurs by 1 AO1

used and oxygen is released diffusion in the leaves of trees, 4.4.2.1

whereas in lungs it is oxygen but involves ventilation /

used and carbon dioxide is breathing in the lungs of animals

released

Total 8 19

How to answer it

Deforestation: reasons, impacts, and the “lungs of the planet” idea

What this question tests

AO1 recall of why deforestation happens and what it does to the environment, plus a simple explanation of gas exchange in forests and lungs. To score full marks, you need to mention both reasons and effects, and in the final parts you must compare what happens in forests with what happens in lungs.

Question 07.1 — Describe the reasons why deforestation takes place and the effects deforestation has on the environment. [6 marks]

Best answer structure: give a few reasons, then a few effects, with scientific detail

✅ Correct answers

  • Reasons: forests are cleared for land to farm animals or crops, such as cattle, rice, coffee, wheat, or sheep.
  • Land may be cleared for mining.
  • Forests may be cut down for wood used in building or to make paper.
  • Land may be cleared to grow palm oil or biofuels.
  • Effects: fewer trees means less carbon dioxide is taken in for photosynthesis.
  • More dead plant material may decay or be burned, releasing carbon dioxide.
  • More carbon dioxide in the atmosphere increases the greenhouse effect and can lead to global warming.
  • Deforestation destroys habitats, causing reduced biodiversity.
  • Removing trees can also lead to soil erosion.
Examiner note: Level 2 answers needed both reasons and effects, not just one side.

💡 Key knowledge

  • Tropical rainforests are often cleared for farming and plantations.
  • Temperate forests may be cleared for timber, farming, or paper production.
  • Trees remove carbon dioxide from the atmosphere during photosynthesis.
  • When forests are removed, the carbon cycle is disrupted.
  • Habitats are lost, so fewer species can survive.

🧠 Exam technique

  • For 6 marks, do not list just one reason and one effect.
  • Write in connected sentences so the examiner can see clear scientific explanation.
  • Use precise words like carbon dioxide , photosynthesis , greenhouse effect , and biodiversity .
  • To reach the top level, explain how the effect happens, not just name it.

❌ Common errors

  • Only writing about effects and forgetting reasons, or the other way round.
  • Saying “trees help the environment” without explaining how.
  • Confusing global warming with pollution or acid rain.
  • Missing the link between fewer trees and more carbon dioxide in the atmosphere.
  • Writing “animals lose homes” without using the scientific term habitat loss.

📐 Model 6-mark response

Forests are cut down to clear land for farming, such as cattle, rice, coffee or palm oil plantations, and also for mining or for wood used in building and paper making. Deforestation reduces the number of trees, so less carbon dioxide is taken in for photosynthesis. Dead trees may also decay or be burned, releasing more carbon dioxide into the atmosphere. This increases the greenhouse effect and can lead to global warming. Deforestation also destroys habitats, which reduces biodiversity, and it can cause soil erosion.

This would score highly because it gives multiple reasons and multiple effects, with clear scientific links.

Question 07.2 — Describe one way forests being called “The lungs of the planet” can be considered to be a correct statement. [1 mark]

✅ Correct answer

Forests involve gas exchange with the atmosphere.

This exact idea matches the mark scheme. One clear statement is enough for 1 mark.

💡 Key knowledge

Trees take in carbon dioxide and release oxygen during photosynthesis. This is why people compare forests to lungs: they interact with air gases.

🧠 Exam technique

  • Keep it short and direct.
  • Use the phrase gas exchange for the mark.
  • Do not overcomplicate a 1-mark question.

Question 07.3 — Trees do not have lungs. Describe one other way forests being called “The lungs of the planet” is an incorrect statement. [1 mark]

✅ Correct answers

In forests, carbon dioxide is used and oxygen is released, whereas in lungs oxygen is used and carbon dioxide is released.

💡 Key knowledge

  • Forest gas exchange happens in leaves by diffusion.
  • Lungs involve breathing/ventilation to move air in and out.
  • So forests and lungs do not work in exactly the same way.

❌ Common errors

  • Saying “trees have no lungs” is true, but it does not explain why the statement is incorrect.
  • Only saying “they are different” without naming the gases.
  • Mixing up the gas roles: forests take in CO₂ and release O₂; lungs take in O₂ and release CO₂.

🧠 Exam technique

For a 1-mark compare-and-contrast question, give one accurate difference. The easiest full-mark point is the gas difference:

Forests use carbon dioxide and release oxygen, but lungs use oxygen and release carbon dioxide.

Quick revision summary

💡 Remember

  • Deforestation happens for farming, mining, wood, and plantations.
  • It reduces photosynthesis, so less CO₂ is removed.
  • Burning and decay release more CO₂.
  • This increases the greenhouse effect and can lead to global warming.
  • It also causes habitat loss, reduced biodiversity, and soil erosion.

🧠 How marks were awarded

  • 07.1: marks for scientifically relevant reasons and effects; detailed, accurate explanation reaches Level 2.
  • 07.2: 1 simple correct statement about gas exchange.
  • 07.3: 1 clear difference between forests and lungs.

❌ Top trap to avoid

Do not just write general statements like “deforestation is bad.” Always include a scientific reason or effect if you want the marks.

Topics

Biology · B4: Bioenergetics · B7: Ecology

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 2 (Higher), 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.