5. The diagram shows the human digestive system.
[VISUALIZATION: Diagram of the human digestive system, labelling the mouth, oesophagus, stomach, small intestine, large intestine, liver, gall bladder, pancreas, rectum, anus. The gall bladder is labelled X.]
Question
(a) Identify the organ labelled X where bile is stored. [1]
Hint
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Hint
Locate label X on the diagram and identify the associated organ known for bile storage.
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Gall bladder
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Question
(b) Outline the initial steps of protein digestion that occur in the stomach. [3]
Hint
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Hint
Think about the environment of the stomach and the specific enzymes involved in breaking down proteins.
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The stomach wall secretes acid creating a low pH environment. Protease enzymes (like pepsin), also secreted by the stomach wall, begin protein digestion, breaking proteins into smaller polypeptides.
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Question
(c) Explain the importance of the large surface area provided by the villi in the small intestine. [3]
Hint
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Hint
Relate the structural adaptations (villi, microvilli) to the primary function of the small intestine, which is nutrient absorption.
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Villi and microvilli greatly increase the surface area for absorption, allowing for more efficient and faster uptake of digested nutrients. A rich blood supply transports these nutrients away, maintaining the concentration gradient.
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