# The spongy mesophyll layer is an important part of a leaf for gas exchange. Explain how the structure of the spongy mesophyll layer makes gas exchange efficient.

> Eduqas A-Level Biology — 2.2 Adaptations for gas exchange · Explain · 5 marks

> Plants require carbon dioxide for photosynthesis and must also remove oxygen produced during this process. Gas exchange in leaves takes place mainly in the spongy mesophyll layer.

## Mark scheme (5 marks)

1. The spongy mesophyll cells are loosely packed, creating air spaces between them
2. The air spaces increase the surface area available for gas exchange
3. Gases diffuse faster because the diffusion distance is short / cells are thin
4. A large concentration gradient is maintained because gases are used up or removed
5. The moist cell surfaces allow gases to dissolve before diffusing across the cell membrane

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Biology](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/the-spongy-mesophyll-layer-is-an-94bc01e8) · Published by Druglandscape Ltd.