Explain why the leaves of most plants are broad and flat.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
A broad, flat leaf has a large surface area, which allows more light to be absorbed for photosynthesis.
A larger surface area also permits more carbon dioxide to diffuse into the leaf.
The increased light and CO₂ uptake raises the rate of photosynthesis, producing more glucose.
A larger surface area also permits more carbon dioxide to diffuse into the leaf.
The increased light and CO₂ uptake raises the rate of photosynthesis, producing more glucose.
Examiner tips
- Use the word "broad" and "flat" to show understanding of leaf shape. Mention both light absorption and CO₂ diffusion as reasons. Link increased uptake to higher photosynthetic rate and glucose production.
Common mistakes
- Failing to mention both light and CO₂. Using vague terms like "good shape" instead of "large surface area". Omitting the link to increased glucose production.
Mark scheme (4 marks)
- A broad, flat leaf has a large surface area
- This allows more light to be absorbed / captured for photosynthesis
- A broad, flat leaf also allows more carbon dioxide to diffuse into the leaf
- More light / carbon dioxide means the rate of photosynthesis is increased / more glucose can be produced
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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