# Explain why a piece of potato placed in a concentrated salt solution will decrease in mass.

> AQA A-Level Biology (7402) — 3.2.3 Transport Across Membranes · Explain · 5 marks

> A student cuts identical pieces of potato and places them into different concentrations of salt solution. After 30 minutes, the student removes the potato pieces and measures their mass.

## Mark scheme (5 marks)

1. Water moves out of the potato cells by osmosis
2. The salt solution has a lower water concentration than the potato cell cytoplasm / vacuole
3. Water moves from a higher water concentration (inside the cell) to a lower water concentration (in the salt solution)
4. Water passes through the partially permeable membrane (of the potato cells)
5. The potato cells lose water so the cells become flaccid / the tissue shrinks, causing a decrease in mass

## Related

- [Revision notes for AQA A-Level Biology (7402)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-a-piece-of-potato-e5df9c4a) · Published by Druglandscape Ltd.