# Explain how the villi of the small intestine are adapted to absorb glucose efficiently into the blood, referring to both diffusion and active transport in your answer.

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

## Mark scheme (5 marks)

1. Glucose moves by diffusion from the small intestine lumen into the epithelial cells / villus cells down a concentration gradient
2. Active transport is used to move glucose from the epithelial cells into the blood / capillaries when the concentration of glucose in the blood is higher than in the cells
3. Active transport requires energy (from respiration) / uses carrier proteins
4. Villi have a large surface area to increase the rate of absorption / diffusion
5. Villi have a rich blood supply / capillary network that maintains a concentration gradient for glucose

## Key terms

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

## 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-how-the-villi-of-the-dbba535e) · Published by Druglandscape Ltd.