Explain how deforestation can affect the amount of carbon dioxide in the atmosphere.

Eduqas GCSE Biology — 1.6.3 Human impact on the environment · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Trees and plants absorb CO₂ during photosynthesis, removing it from the atmosphere.
When forests are cut down, fewer trees are available to take up CO₂, so less gas is removed.
Often the cut trees are burned or decompose, releasing stored CO₂ back into the air.
These two effects together raise the amount of CO₂ in the atmosphere, contributing to the greenhouse effect and global warming.

Examiner tips

Use the term ‘photosynthesis’ and ‘CO₂’ to show understanding. Explain both the loss of absorption and the release of CO₂. Link the increase in CO₂ to the greenhouse effect to earn the full mark.

Common mistakes

Confusing ‘absorb’ with ‘store’ – students say trees store CO₂ but don’t mention removal. Forgetting to mention the burning/decomposition release of CO₂. Using vague language like ‘more CO₂’ without explaining the cause.

Mark scheme (4 marks)

Trees/plants remove carbon dioxide from the atmosphere by photosynthesis
Fewer trees means less carbon dioxide is removed / absorbed from the atmosphere
Trees are often burned when land is cleared, releasing carbon dioxide
Both effects together cause an increase in atmospheric carbon dioxide / contribute to the enhanced greenhouse effect / global warming

Key terms in this question

deforestation · carbon dioxide · atmosphere