Question Constellation Sign up for free AQA · GCSE · Biology · Higher
Protein and fat digestion
A drinks company claims that a drink contains protein and fat. The human digestive system breaks down protein and fat in the drink.
Describe how protein and fat are digested. You should include:
- the enzymes involved
- where the enzymes are produced.
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Marking points
- 1 Describes protein digestion and correctly links protein to protease.
- 2 Describes fat digestion and correctly links fat to lipase.
- 3 Gives a detailed, scientifically accurate account rather than a list of disconnected facts.
- 4 Includes relevant enzyme production sites and/or accurate roles of acid and bile.
Full-mark answer
Proteases digest proteins into amino acids. Proteases are produced in the stomach, pancreas and small intestine, and hydrochloric acid in the stomach provides a suitable pH for the stomach protease. Lipases digest fats into fatty acids and glycerol. Lipases are produced in the pancreas and small intestine. Bile is produced by the liver and released from the gall bladder; it neutralises stomach acid and emulsifies fat, increasing the surface area on which lipase can act.
Why this answer loses marks
Protein and fat are broken down by enzymes.
This does not pair either nutrient with its enzyme, products, and production sites, so it cannot form the detailed account required.