# Explain how the structure of a villus epithelial cell (enterocyte) is adapted for the absorption of digested nutrients from the small intestine.

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

## Mark scheme (4 marks)

1. Microvilli / brush border greatly increases the surface area of the apical membrane
2. Large numbers of mitochondria provide ATP for active transport of nutrients (e.g. glucose, amino acids) across the membrane
3. Transport proteins (carrier proteins / channel proteins) embedded in the apical membrane allow facilitated diffusion or active transport of specific molecules
4. The basal membrane / basolateral membrane is in close proximity to blood capillaries, allowing rapid transfer of absorbed nutrients into the blood / lymph (lacteals for fats)

## Key terms

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

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](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-structure-of-a-e8bc4dfa) · Published by Druglandscape Ltd.