# Describe how the rate of photosynthesis in a plant is affected when the concentration of carbon dioxide in the air increases from a very low level to a high level.

> WJEC GCSE Biology (Wales) — 1.5.2 Photosynthesis · Describe · 4 marks

## Mark scheme (4 marks)

1. At low carbon dioxide concentrations, the rate of photosynthesis is low
2. As carbon dioxide concentration increases, the rate of photosynthesis increases
3. Carbon dioxide is a raw material / reactant used in photosynthesis
4. At high carbon dioxide concentrations the rate levels off / plateaus because another factor becomes limiting

## Key terms

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

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" 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/describe-how-the-rate-of-photosynthesis-c9ddb378) · Published by Druglandscape Ltd.