# Explain how auxin causes a plant shoot to grow towards a light source. In your answer, refer to the distribution of auxin and the effect it has on cells.

> AQA GCSE Biology (8461) — 4.5.4 Plant hormones (Bio only) · Explain · 4 marks

## Mark scheme (4 marks)

1. Light causes auxin to move to / accumulate on the shaded side of the shoot
2. Higher concentration of auxin on the shaded side causes cells on that side to elongate more / grow faster
3. Cells on the shaded side are longer than cells on the light side
4. The shoot bends / curves towards the light source

## Key terms

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

## Related

- [Revision notes for AQA GCSE Biology (8461)](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-how-auxin-causes-a-plant-bb8f8f1f) · Published by Druglandscape Ltd.