# Describe how auxin causes a plant root to grow towards gravity.

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

> When a plant root is placed horizontally, it will bend downwards over time. Auxin is unevenly distributed in the root as a result of gravity.

## Mark scheme (4 marks)

1. Gravity causes auxin to move to / accumulate on the lower side of the root
2. Higher concentration of auxin on the lower side inhibits / slows cell elongation on that side
3. Lower concentration of auxin on the upper side allows / promotes cell elongation on that side
4. The difference in elongation between the two sides causes the root to bend / grow downwards

## Key terms

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

## Related

- [Revision notes for Eduqas GCSE Biology](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-auxin-causes-a-plant-639041d1) · Published by Druglandscape Ltd.