Science (086) — AI-generated practice question

The student's argument is incorrect. While digestion is indeed completed in the small intestine, absorption of nutrients into the blood is not automatic — it depends critically on the structure of the villi.

Why villi structure matters:

1. Increased surface area: The numerous finger-like projections called villi greatly increase the inner surface area of the small intestine, allowing faster and more efficient absorption of digested food.

1. Rich blood supply: Villi are richly supplied with blood vessels, which carry absorbed nutrients (glucose, amino acids) directly to all body cells.

1. Fat absorption: Fatty acids and glycerol are also absorbed through the villi into the lymph vessels (lacteals) before reaching the bloodstream.

1. Without villi: If the lining were flat, the surface area would be drastically reduced, absorption would be extremely slow and incomplete, and cells would be deprived of nutrients despite complete digestion.

Conclusion: Digestion and absorption are two distinct processes. The villi's specialised structure is essential for efficient absorption; without it, digested nutrients would largely pass out of the body unabsorbed.

Source: Chapter 5 — Life Processes, Section 5.2.4 Nutrition in Human Beings

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Examiners look for: (1) a clear rebuttal of the argument, (2) specific mention of surface area increase, (3) role of blood vessels in villi, and (4) distinction between digestion and absorption. The key textbook line is: "The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption... richly supplied with blood vessels." Never confuse digestion (breaking down food) with absorption (taking it into blood) — they are separate processes.