AQA GCSE Biology Biology Paper 2 (Higher), June 2025: Question 5
9 marks · Standard Demand difficulty · Extended Answer
State uses of peat, define biodiversity, and explain how the destruction of peat bogs affects biodiversity both locally and globally.
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Question text
05 Peat bog is a specialised habitat for some living organisms.
05.1 Peat has been removed from peat bogs so that the land can be used for
farming or forestry.
Give two uses of the peat removed from peat bogs.
[2 marks]
The destruction of peat bogs can affect biodiversity.
05.2 What is meant by ‘biodiversity’?
[1 mark]
05.3 Explain how the destruction of peat bogs can affect biodiversity:
• in the local area
• globally.
[6 marks]
Extra space
Mark scheme
Show the mark scheme
Question 5
AO /
Question Answers Extra information Mark
Spec. Ref.
05.1 for burning / combustion allow as a fuel 1 AO1
4.7.3.3
as compost allow for growing plants 1
ignore as fertiliser
allow to improve soil drainage /
texture / quality
allow as a building material
allow as animal feed /
supplement
AO /
Spec. Ref.
05.2 the variety of (all) species on allow the number of (all) species 1 AO1
Earth on Earth 4.7.3.1
or
the variety of (all) species in a allow the number of (all) species
habitat / area / ecosystem / in a habitat / area / ecosystem /
community community
AO /
Question Answers Mark
Spec. Ref.
Level 3: Relevant points (reasons / causes) are identified, given in
05.3 5–6 AO1
detail and logically linked to form a clear account.
4.7.2.4
Level 2: Relevant points (reasons / causes) are identified, and 4.7.3.1
3–4 4.7.3.3
there are attempts at logical thinking. The resulting account is not
fully clear. 4.7.3.5
Level 1: Points are identified and stated simply, but their relevance
1–2
is not clear and there is no attempt at logical thinking.
No relevant content
Indicative content
• (destruction of peat) causes decrease in biodiversity locally /
globally
Local effects
• causes death / extinction of (local) populations / species
o (due to) loss of (specialised) habitat
o (so) lack of food
o (so) lack of shelter
• causes migration of (local) populations / species
o (due to) loss of (specialised) habitat
o (so) need to find food
o (so) need to find shelter
Global effects
• (removal of peat) releases (trapped) carbon dioxide
• (removal of peat) releases (trapped) methane
• burning peat releases carbon dioxide
• decay of peat releases carbon dioxide (from respiration of
microorganisms)
• decay of peat releases methane (from anaerobic respiration of
microorganisms)
o (causes) global warming or greenhouse effect
o (causes) climate change or extreme weather
o (causes) melting ice caps or rising sea levels or flooding
o (causes) drought / desertification or changing rainfall
patterns
o (causes) loss of food / habitats
o (so) migration patterns change
o (so) some species / organisms become extinct
For Level 2, must refer to local and global effects with an explanation.
For Level 3, must give an explanation for local and for global effects
supported by other details for local and / or global effects.
Total Question 5 9
How to answer it
Peat Bogs, Global Warming & Biodiversity
This question assesses knowledge from Topic B7 (Ecology), specifically focusing on human impacts on ecosystems:
- Commercial uses of peat (fuel, compost).
- The precise biological definition of biodiversity.
- Linking peat bog destruction to local habitat loss and global climate change in an extended 6-mark logical explanation.
Uses of Peat Removed from Peat Bogs
State two ways humans utilise harvested peat
✅ Acceptable Answers (Any Two)
- As fuel / for burning / combustion [1 mark]
- As compost / for growing plants / improving soil quality [1 mark]
❌ Common Errors & Pitfalls
- Do NOT write "fertiliser": Peat improves soil texture and retains moisture, but it is low in plant nutrients; examiners specifically instruct to ignore fertiliser.
- Vague answers: Saying just "farming" or "gardening" without specifying compost or fuel loses the mark.
Definition of Biodiversity
Recall the exact biological meaning of the term
✅ Correct Definition
The variety of all the different species of organisms on Earth, or within a specific ecosystem / habitat.
🧠 Key Keyword
You must use the word species or organisms. Saying "the variety of life" or "the number of all living things" is often too vague. Make sure you write "variety of species".
How Peat Bog Destruction Affects Biodiversity: Local vs Global
Constructing a Level 3 (5–6 marks) explanation
🧠 How Examiners Grade This 6-Marker
- Level 3 (5–6 marks): Clear, logical account explaining both local effects and global effects with step-by-step causes and consequences.
- Level 2 (3–4 marks): Mentions both local and global effects, but one is only stated simply without a clear causal chain.
- Level 1 (1–2 marks): Isolated points stated without clear explanation or link to biodiversity.
📍 Part 1: Local Effects (In the Bog Area)
Peat bogs are unique, waterlogged, acidic habitats hosting specialised organisms.
- Destruction of habitat: Draining and digging up bogs destroys specialised wetland habitats.
- Loss of food and shelter: Unique plant and animal species lose their food sources and breeding grounds.
- Consequence: Causes local populations to die out or migrate elsewhere, leading to a reduction in local biodiversity or even local extinction.
🌍 Part 2: Global Effects (Worldwide Impact)
Peat stores enormous amounts of dead, undecayed plant material (carbon sink).
- Release of Greenhouse Gases:
- When drained, oxygen enters, allowing microorganisms (decomposers) to aerobically respire, releasing CO₂.
- When peat is burned as fuel, combustion releases CO₂.
- Global Warming: Increased CO₂ in the atmosphere intensifies the greenhouse effect, driving climate change.
- Consequence for Global Biodiversity:
- Melting polar ice caps and rising sea levels destroy coastal habitats.
- Droughts, floods, and extreme temperatures destroy habitats elsewhere, forcing migration and causing extinctions globally.
✅ Model Answer Plan for Full 6 Marks
- Local impact: "Destruction of peat bogs removes a specialised habitat. This reduces food supply and nesting sites for bog-dwelling plants and animals, forcing species to migrate or die, which reduces local biodiversity."
- Global impact mechanism: "Peat contains trapped carbon. When peat is drained, microbes decay the organic matter via respiration, releasing carbon dioxide (CO₂). Burning peat as a fuel also releases CO₂."
- Global link to biodiversity: "Excess CO₂ enhances the greenhouse effect, driving global warming and extreme climate events (such as droughts and floods). This destroys habitats worldwide (e.g., polar ice melting), leading to global species loss."
❌ Common Student Mistakes in this 6-Marker
- Only answering one half: Many students write entirely about global warming and forget to discuss the local bog habitat (capping their score at Level 2, max 4 marks).
- Confusing the role of decay: Peat does not release CO₂ just because it is cut; it releases CO₂ because aerobic decay by bacteria/fungi begins when air enters the drained peat, or because it is combusted.
- Forgetting to link back to biodiversity: Just explaining the greenhouse effect is not enough—you must conclude with how it causes death of species or extinction worldwide.
Topics
Biology · B7: Ecology
Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Higher), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.