# Explain how the structure of a root hair cell is adapted for the absorption of water and mineral ions from the soil.

> IB DP Biology Standard Level (2023 syllabus) — B2.3 Cell specialisation · Explain · 4 marks

## Mark scheme (4 marks)

1. Root hair cells have a long, thin hair-like extension that greatly increases the surface area of the cell membrane in contact with soil water.
2. Root hair cells have a large central vacuole containing a concentrated cell sap, which lowers the water potential inside the cell, maintaining a water potential gradient so water enters by osmosis.
3. Root hair cells possess a high density of protein carrier / transporter proteins (ion channels / pumps) in their plasma membrane for the active transport of mineral ions against their concentration gradient.
4. Root hair cells contain many mitochondria to provide ATP (via aerobic respiration) to power the active transport of mineral ions.

## Key terms

- [root hair cell](https://www.gradenine.co.uk/glossary/root-hair-cell)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-structure-of-a-697453bd) · Published by Druglandscape Ltd.