# Explain why the waxy cuticle and the distribution of stomata on a leaf are important for limiting water loss whilst still allowing gas exchange to occur.

> Pearson Edexcel International GCSE Biology (4BI1) — 2.8 Gas exchange: flowering plants · Explain · 4 marks

## Mark scheme (4 marks)

1. The waxy cuticle reduces / prevents water loss by evaporation from the upper leaf surface
2. Stomata are mainly found on the lower (abaxial) surface, away from direct sunlight, which reduces the rate of evaporation / water loss
3. Stomata can open and close to allow carbon dioxide in and oxygen out (or vice versa) for gas exchange
4. Stomata close (e.g. in dry / dark conditions) to reduce water loss when gas exchange is less needed

## Key terms

- [waxy cuticle](https://www.gradenine.co.uk/glossary/waxy-cuticle)
- [stomata](https://www.gradenine.co.uk/glossary/stomata)
- [gas exchange](https://www.gradenine.co.uk/glossary/gas-exchange)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](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-why-the-waxy-cuticle-and-8edb2722) · Published by Druglandscape Ltd.