O-LevelBiologyHuman Nutrition5090/21 · Oct/Nov 2023 · Q511 Marks

Fig. 5.1 shows two structures found in the human digestive system. [Figure 5.1]

(a)(i)Identify the type of tooth shown in the diagram.[1]
(a)(ii)Name the outer layer of the tooth.[1]
(a)(iii)Explain how the tooth and the salivary gland contribute to digestion in different ways.[4]
(b)(i)The stomach wall produces different substances that are involved in digestion. Name two of these substances and explain how they are involved in digestion.[4]
(b)(ii)A hormone called gastrin stimulates cells in the stomach wall to release the substances involved in digestion. Some of the gastrin is produced in the duodenum. State how this gastrin reaches the stomach.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.

[1] 5(a)(i) molar / premolar ;
[1] 5(a)(ii) enamel ; Ig crown
[4] 5(a)(iii) any two from: tooth: physical digestion ; grinds / breaks up food into smaller pieces / larger surface area ridged surface / hard-wearing surface ; any two from: salivary gland: chemical digestion ; produces amylase / enzyme ; starch broken down to maltose ;
[4] 5(b)(i) hydrochloric acid ; Ig references to killing bacteria optimum / best acidity / correct pH + enzyme action ; pepsin / protease ; protein broken down to polypeptides / peptides / amino acids;
[1] 5(b)(ii) in the blood / bloodstream / plasma ;

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