# A student places a healthy oak tree seedling in a dark cupboard for several days. When the seedling is returned to a sunny windowsill, new leaf growth resumes. Explain why the seedling was unable to produce new growth whilst in the dark cupboard, referring to the role of photosynthesis in the plant.

> OCR A-Level Biology B — Advancing Biology (H422) — 4.1 Photosynthesis · Explain · 5 marks

> Oak tree seedlings require light to grow. A student observes that a seedling kept in complete darkness stops producing new leaves, but recovers when placed back in sunlight.

## Mark scheme (5 marks)

1. Photosynthesis requires light energy
2. In the dark, the plant cannot convert carbon dioxide and water into glucose
3. Glucose is needed to provide the energy / materials for growth
4. Photosynthesis is an endothermic reaction that takes place in the chloroplasts
5. When returned to sunlight, photosynthesis resumes so glucose is produced again, allowing growth to restart

## Key terms

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

## Related

- [Revision notes for OCR A-Level Biology B — Advancing Biology (H422)](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/a-student-places-a-healthy-oak-a68a05a9) · Published by Druglandscape Ltd.