# A farmer grows crops in a large greenhouse. During winter, the farmer notices that the crops grow much more slowly than in summer. Explain how two different limiting factors could be responsible for the slower growth of crops in the greenhouse during winter.

> OCR GCSE Biology A: Gateway Science (J247) — B1.4 Photosynthesis · Explain · 4 marks

> Greenhouses are used to grow crops throughout the year. However, crop growth rates can vary significantly between seasons even inside a greenhouse.

## Mark scheme (4 marks)

1. Identifies light intensity / light as a limiting factor in winter
2. Explains how reduced light limits photosynthesis / growth — less light energy is absorbed by chlorophyll so the rate of photosynthesis is reduced
3. Identifies temperature as a second limiting factor in winter
4. Explains how lower temperature limits photosynthesis / growth — enzymes involved in photosynthesis work more slowly at lower temperatures, reducing the rate of photosynthesis and glucose production

## Key terms

- [limiting factor](https://www.gradenine.co.uk/glossary/limiting-factor)

## Related

- [Revision notes for OCR GCSE Biology A: Gateway Science (J247)](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/a-farmer-grows-crops-in-a-349ea714) · Published by Druglandscape Ltd.