# Explain why increasing the concentration of carbon dioxide in a greenhouse can increase the rate of photosynthesis, and describe what happens to the rate of photosynthesis if light intensity then becomes a limiting factor.

> Edexcel GCSE Biology (1BI0) — 6.1 Photosynthesis · Explain · 4 marks

> Farmers sometimes pump extra carbon dioxide into their greenhouses to improve crop yields.

## Mark scheme (4 marks)

1. Carbon dioxide is a reactant in photosynthesis
2. Increasing CO₂ concentration increases the rate of photosynthesis (because CO₂ was previously the limiting factor)
3. A limiting factor is a variable that limits the rate of a particular reaction
4. If light intensity is a limiting factor, the rate of photosynthesis will not increase further / will remain constant even if CO₂ is increased

## Key terms

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

## Related

- [Revision notes for Edexcel GCSE Biology (1BI0)](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-increasing-the-concentration-of-431be1e3) · Published by Druglandscape Ltd.