Villi and Absorption

IGCSE Edexcel Biology
2.32 Adaptations for Absorption
Key Concept: Villi increase surface area and speed up absorption in the small intestine.

Section A: Structure

1. Describe four adaptations of the villus for absorption. [4]
2. Label the villus with: villus, capillary, lacteal, epithelium. [4]
[Villus diagram]

Section B: Absorption

3. Explain why digestion must produce small soluble molecules for absorption. [2]
4. Describe what happens to glucose, amino acids, and fatty acids after absorption. [4]
Total marks: 14

Mark Scheme

1. Large surface area, thin epithelium, rich capillary supply, lacteal for fats (any four) [4]
2. All four labels correct [4]
3. Small soluble molecules can diffuse or be transported across the epithelium [2]
4. Glucose and amino acids enter capillaries; fatty acids and glycerol enter lacteal and lymph before blood [4]