Explain why the length of the small intestine differs between herbivores and carnivores. What does this tell us about the relationship between diet and digestive system design?
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer
Herbivores (like cows) eat grass, which contains cellulose — a complex carbohydrate that is difficult to digest. They need a longer small intestine to allow sufficient time and surface area for cellulose digestion. Carnivores (like tigers) eat meat, which is easier to digest, so they have a shorter small intestine.
This shows that an organism's diet directly influences the design of its digestive system. The digestive system is adapted to suit the type of food consumed — a clear example of structure fitting function.
Source: Chapter 5, Section 5.2.4 (Nutrition in Human Beings)
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Explanation
- The textbook explicitly states: "Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine." Quote or paraphrase this directly for full marks.
- Examiners look for: (1) correct reason for longer intestine in herbivores (cellulose digestion), (2) correct reason for shorter in carnivores (meat easier to digest), (3) a concluding link between diet and digestive system design.
- Avoid vague answers — name the specific substance (cellulose) and a specific animal example.