# Explain why a cell membrane is found in both plant cells and bacterial cells, and explain how the nucleus of a plant cell differs in structure from the genetic material in a bacterial cell.

> AQA A-Level Biology (7402) — 3.2.1 Cell Structure · Explain · 5 marks

## Mark scheme (5 marks)

1. The cell membrane controls what substances pass into and out of the cell
2. Both plant cells and bacterial cells need to control which substances enter and leave, so both require a cell membrane
3. In a plant cell the genetic material / DNA is contained within a nucleus
4. In a bacterial cell there is no nucleus / the genetic material is not enclosed in a nucleus
5. The bacterial genetic material / DNA is found in the cytoplasm (as a single circular loop of DNA)

## Key terms

- [cell membrane](https://www.gradenine.co.uk/glossary/cell-membrane)
- [nucleus](https://www.gradenine.co.uk/glossary/nucleus)
- [genetic material](https://www.gradenine.co.uk/glossary/genetic-material)
- [bacterial cell](https://www.gradenine.co.uk/glossary/bacterial-cell)

## Related

- [Revision notes for AQA A-Level Biology (7402)](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-a-cell-membrane-is-3c5bd871) · Published by Druglandscape Ltd.