# Explain how the structure of a leaf is adapted to allow efficient gas exchange in a flowering plant.

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

## Mark scheme (4 marks)

1. Stomata are present (in the lower epidermis) and allow gases to enter and leave the leaf by diffusion
2. The leaf has a large surface area, increasing the area over which diffusion can occur
3. Air spaces in the spongy mesophyll allow gases to circulate / diffuse throughout the leaf
4. The waxy cuticle is thin / absent on the lower surface, so it does not prevent gas exchange / reduces water loss from the upper surface without blocking 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)
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