Practise 26 exam-style questions on Deforestation for AQA GCSE Biology. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
26 questions
4–6 marks each
Instant marking
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20 questions, marked as you go
Sample questions with model answers
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
Question 1
4 marks
Explain what is meant by habitat fragmentation and give two ecological consequences for animal populations.
Model answer
Habitat fragmentation is the breaking of continuous habitat into smaller isolated patches. Consequences: reduced gene flow leading to inbreeding and reduced genetic diversity; smaller populations more vulnerable to stochastic extinction; edge effects which alter microclimate and increase predation.
Explanation
Fragmentation isolates populations so they cannot interbreed, reducing genetic diversity, and small isolated populations are more likely to go extinct. Edges can be harsher and allow predators or invasive species to enter.
Mark scheme
1 mark
Definition: breaking continuous habitat into smaller, isolated patches
Consequence 2: smaller populations more vulnerable to extinction (stochastic events)
1 mark
Alternative consequence: edge effects changing microclimate and increasing predation / invasion by generalists
Question 2
5 marks
Design a simple field sampling method to compare plant species richness in (a) an intact forest patch and (b) an adjacent cleared pasture. Describe one way to ensure your comparison is fair.
Model answer
Use random quadrats (e.g., 1 m²) placed by random coordinates in each habitat; record all plant species in each quadrat; repeat with many replicates (e.g., 20/quadrat). Ensure fair comparison by sampling the same number of quadrats in each habitat and at the same time of year/day.
Explanation
Random quadrats and multiple replicates provide unbiased samples of plant species. Sampling both habitats the same number of times and in the same season ensures a fair comparison of richness.
Mark scheme
1 mark
Use quadrat sampling (specify size, e.g., 1 m²)
1 mark
Place quadrats randomly (eg using random coordinates) in each habitat
1 mark
Record all plant species present in each quadrat and count species (species richness)
1 mark
Repeat many times (replicates) in each habitat (e.g., 15–30 quadrats)
1 mark
Fairness: sample same number of quadrats in each area and sample at same time/season
Question 3
5 marks
Explain how deforestation can affect the water cycle at both local and regional scales.
Model answer
Locally, removal of trees reduces transpiration leading to lower humidity and possibly reduced local precipitation; soils become less able to retain water so runoff and flooding increase and groundwater recharge decreases. Regionally, large-scale deforestation can reduce evapotranspiration, altering atmospheric moisture transport and reducing rainfall over downwind areas.
Explanation
Trees recycle water via transpiration and intercept rainfall. Removing them changes runoff, infiltration and regional rainfall, increasing flood risk and possibly reducing rainfall in other areas dependent on evapotranspiration.
Mark scheme
1 mark
Local: less transpiration from trees reduces local humidity and possibly reduces local rainfall
1 mark
Local: reduced interception and root uptake increases surface runoff and erosion and reduces groundwater recharge
1 mark
Regional: large-scale deforestation reduces evapotranspiration and can change regional atmospheric moisture and rainfall patterns
1 mark
Regional: may alter monsoon patterns or reduce water availability downwind
1 mark
Link to impacts (e.g., reduced water for agriculture / communities) provided as additional explanation
Question 4
6 marks
A restoration project proposes planting a single native tree species across a degraded area. Discuss three ecological advantages and two risks of using a single native species (a native monoculture) for initial restoration.
Model answer
Advantages: fast canopy closure reduces erosion; native species compatible with local ecology supporting some fauna; simpler management and predictable growth. Risks: still low structural/biodiversity compared with mixed planting; disease or pest could wipe out the single species; may fail to recreate full ecosystem functions and interactions.
Explanation
Planting a native species can stabilise soils and begin ecosystem recovery, but a single-species cover lacks the diversity and resilience of a mixed forest and can be vulnerable to collapse from pests or disease.
