O-LevelBiologyHuman Nutrition5090/22 · Oct/Nov 2019 · Q410 Marks

Proteins are an important component of the human diet. Protein molecules are digested and the products of digestion are absorbed into the blood.

(a)(i)State one principal source of protein in the diet.[1]
(a)(ii)Describe the chemical digestion of proteins in named parts of the alimentary canal.[4]
(a)(iii)State where in the alimentary canal the products of digestion are absorbed into the blood.[1]
(b)In a disease that affects a small number of people, the surface through which the products of digestion are absorbed into the blood changes. This change is shown in the diagrams below. Both diagrams are drawn to the same scale. [Figures showing absorption surface in a person not affected by the disease and an absorption surface in a person affected by the disease] Describe the change in the absorption surface in a person affected by the disease and suggest ways in which the person may be affected by this change.[4]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

[1] meat / fish / eggs / dairy products / nuts / pulses ;
[4] stomach; small intestine / duodenum / ileum ; protease / pepsin / trypsin / erepsin / rennin / peptidases; into AW + amino acids / polypeptides / peptides / peptones ;
[]
[4] less / reduced / smaller / small / shorter / short; area; less + diffusion / active transport; of + glucose / amino acids / fatty acids / glycerol / vitamins / minerals; less + assimilation ; result of deficiency in a component named in 4 ; more food required in diet AW ;

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