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Revision quiz for nutrition and digestion for IGCSE Biology NB, where there are () parentheses, the word is optional; where there are / slashes, you only needed to write one of the alternatives 1. What is peristalsis and where does it happen? (2) - The movement of food by (circular) muscle (contraction) in the oesophagus/small intestine/large intestine 2. Which enzyme does saliva contain, and what substance does it break down? (2) - Amylase, breaks down starch (into maltose) 3. What does the stomach do? (3) - (hydrochloric/stomach) acid kills bacteria - Food is churned/pummelled (to increase surface area) - Pepsin/protease: (begins the) digestion of protein 4. What does the pancreas produce? (3) - Amylase, protease, lipase 5. Define digestion (2) - Breaking down large insoluble molecules into small, soluble ones (that we can absorb) 6. How is the small intestine adapted for efficient absorption (3) - It has a large surface area because it is: (1 or more of) long, folded and has villi and microvilli - Short distance for diffusion because it has a thin wall - (it has blood vessels close the surface to provide a concentration gradient) 7. What does bile do and which organ produces it? (3) - splits up/emulsifies lipids (to increase their surface area) - Neutralizes (stomach) acid so digestive enzymes work at optimum pH 8. Name two important minerals and state their role in the body. (4) - iron to produce haemoglobin (in red blood cells) - Calcium to build strong bones (and teeth) 9. What does the large intestine do? (1) - (re)absorbs water 10. How do different temperatures affect enzymes? - Low temperature: they work slowly - Optimum temperature: work fastest - High temperature: are denatured (so stop working) (3)