# Describe how the alveoli are adapted to act as an efficient exchange surface for gaseous exchange.

> Cambridge International IGCSE Biology (0610) — 11.1 Gas exchange in humans · Describe · 4 marks

## Mark scheme (4 marks)

1. Large surface area to allow more efficient/rapid diffusion
2. Thin walls / short diffusion distance to allow rapid diffusion
3. Good blood supply / network of capillaries to maintain a steep/concentration gradient
4. Good ventilation with air to maintain a steep/concentration gradient

## Key terms

- [alveoli](https://www.gradenine.co.uk/glossary/alveoli)
- [exchange surface](https://www.gradenine.co.uk/glossary/exchange-surface)
- [gaseous exchange](https://www.gradenine.co.uk/glossary/gaseous-exchange)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-the-alveoli-are-adapted-573df3d5) · Published by Druglandscape Ltd.