# Explain why active transport is needed to absorb mineral ions into root hair cells, even when the concentration of mineral ions is already higher inside the root hair cell than in the surrounding soil water.

> Pearson Edexcel International GCSE Biology (4BI1) — 2.4 Movement of substances into and out of cells · Explain · 4 marks

## Mark scheme (4 marks)

1. Mineral ions must move against the concentration gradient (from a more dilute solution to a more concentrated solution)
2. Diffusion cannot move substances against the concentration gradient / diffusion only moves particles from high to low concentration
3. Active transport requires energy from respiration
4. Active transport moves mineral ions from the soil water (more dilute) into the root hair cell (more concentrated), allowing the cell to absorb ions it needs

## Key terms

- [active transport](https://www.gradenine.co.uk/glossary/active-transport)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](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-active-transport-is-needed-9ec1514a) · Published by Druglandscape Ltd.