# Explain why cells in the meristem of a plant root tip have a higher proportion of cells in mitosis compared with cells taken from a mature leaf of the same plant.

> OCR A-Level Biology A (H420) — 2.6 Cell division, diversity and organisation · Explain · 4 marks

> Meristem cells are undifferentiated, rapidly dividing cells found at the growing tips of plant roots. Cells in a mature leaf are differentiated and perform specialised functions such as photosynthesis.

## Mark scheme (4 marks)

1. Meristem cells are undifferentiated and retain the ability to divide by mitosis
2. Mature leaf cells are differentiated and have permanently lost the ability to divide by mitosis
3. Differentiation involves permanent changes to gene expression, so genes required for cell cycle control are no longer expressed in mature leaf cells
4. The root tip meristem produces new cells needed for growth / elongation of the root, so a high rate of mitosis is required in that region

## Key terms

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

## Related

- [Revision notes for OCR A-Level Biology A (H420)](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-why-cells-in-the-meristem-deb1bd47) · Published by Druglandscape Ltd.