Human Digestive System Functions

00:00 7 marks

**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.]

(a) Identify the organ labelled X where bile is stored. [1]
(b) Outline the initial steps of protein digestion that occur in the stomach. [3]
(c) Explain the importance of the large surface area provided by the villi in the small intestine. [3]

Part a

1 minutes 1 marks

Question

(a) Identify the organ labelled X where bile is stored. [1]

Hint Hint

Hint

Locate structure X in the diagram, which is situated near the liver.

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Gall bladder

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Part b

4 minutes 3 marks

Question

(b) Outline the initial steps of protein digestion that occur in the stomach. [3]

Hint Hint

Hint

Consider the secretions of the stomach lining and the type of enzyme active in that environment.

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Stomach wall secretes acid / creates acidic environment / low pH. Protease enzymes (secreted by stomach wall) begin protein digestion. Proteins are broken down into smaller polypeptides.

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Part c

5 minutes 3 marks

Question

Hint Hint

Hint

Think about the primary function of the small intestine and how surface area affects the rate of processes like absorption.

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Villi greatly increase the surface area available for absorption. Microvilli on the surface of epithelial cells further increase surface area. This allows for more efficient/faster absorption of digested nutrients/monomers. A rich capillary supply / lacteal present helps transport absorbed nutrients away / maintain concentration gradient.

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