Explain why most foods eaten by a human must be digested.

Mark scheme

Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.

1. [4] 1 broken down / hydrolysed ;
2. 2 (to) small / smaller / simpler + molecules ;
3. 3 soluble / dissolve ;
4. 4 (to enable) absorption ;
5. 5 (by) diffusion / active transport ;
6. 6 into + blood / capillaries ;
7. 7 into + lymph / lacteal ;
8. 8 (to enable) assimilation or named small to named large molecule ;
9. [6] maximum 4 marks for liver maximum 4 marks for pancreas
10. (either liver or pancreas)
11. 1 neutralisation ;
12. 2 optimum AW pH for enzyme activity or avoid denaturation of enzymes ;
13. (liver only)
14. 3 bile ;
15. 4 emulsification + fats or large fat droplets into smaller droplets AW ;
16. 5 increased surface area ;
17. 6 lipase + production AW of fatty acids and glycerol ;
18. (pancreas only)
19. 7 production / release + enzymes ;
20. 8 protease / trypsin / lipase / amylase ;
21. 9 named substrate + named products for a correct named enzyme ;
22. 10 production of + alkali / hydrogencarbonate / bicarbonate ;