# Explain how the unequal distribution of auxin in a plant shoot causes the shoot to bend towards a light source.

> Eduqas GCSE Biology — 4.4 Plant hormones · Explain · 4 marks

> A plant shoot is placed on a windowsill where light comes from one side only.

## Mark scheme (4 marks)

1. Auxin moves to the shaded side of the shoot
2. Higher concentration of auxin on the shaded side causes greater cell elongation on that side
3. The shaded side grows faster/longer than the light side
4. This unequal growth causes the shoot to bend/curve towards the light

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Biology](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-the-unequal-distribution-of-87ce8a76) · Published by Druglandscape Ltd.