# A student places a green plant on a windowsill in bright sunlight. Explain why the rate of photosynthesis in the plant may increase at first but then stop increasing even if light intensity continues to rise.

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

> Plants carry out photosynthesis using light energy, carbon dioxide, and water. The rate at which photosynthesis occurs can be affected by several limiting factors.

## Mark scheme (4 marks)

1. Photosynthesis requires carbon dioxide and water as raw materials (as well as light energy)
2. Increasing light intensity increases the rate of photosynthesis initially
3. The rate stops increasing because another factor becomes a limiting factor
4. Named example of a limiting factor other than light, e.g. carbon dioxide concentration or temperature

## Key terms

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

## 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-student-places-a-green-plant-d7fa5cc0) · Published by Druglandscape Ltd.