# Explain why water moves out of a red blood cell when it is placed in a concentrated salt solution.

> WJEC GCSE Biology (Wales) — 1.1.2 Movement of substances · Explain · 4 marks

> A red blood cell is placed into a concentrated salt solution. After a short time, the cell shrinks.

## Mark scheme (4 marks)

1. Water moves by osmosis
2. The salt solution has a lower water concentration than the inside of the cell / the water concentration is higher inside the cell than outside
3. Water moves through the partially permeable membrane
4. Water moves from an area of higher water concentration to an area of lower water concentration (down its concentration gradient)

## Related

- [Revision notes for WJEC GCSE Biology (Wales)](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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