# Explain how the structure of a leaf is adapted to maximise the rate of photosynthesis.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 6 Immunity, Infection and Forensics · Explain · 5 marks

## Mark scheme (5 marks)

1. The palisade mesophyll layer is located near the top of the leaf / below the upper epidermis
2. The palisade mesophyll layer contains the greatest concentration of chloroplasts, so it absorbs the most light for photosynthesis
3. The upper epidermis is transparent, allowing light to pass through to the palisade mesophyll tissue
4. The spongy mesophyll layer has air pockets / is loosely packed, which increases the surface area for gas exchange, allowing carbon dioxide to reach photosynthetic cells
5. Stomata (controlled by guard cells) open to allow carbon dioxide to enter the leaf for photosynthesis

## Key terms

- [photosynthesis](https://www.gradenine.co.uk/glossary/photosynthesis)

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-structure-of-a-3c52b909) · Published by Druglandscape Ltd.