O-LevelBiologyHuman Nutrition5090/21 · Oct/Nov 2015 · Q610 Marks

Explain why most foods must be digested.

(a)Explain why most foods must be digested.[3]
(b)Describe the digestion of fats. You should include reference to the following in your answer: : named regions of the alimentary canal and associated organs : named chemicals, including the end products of fat digestion.[7]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.

[max. 3] (a) molecules large + must be converted to smaller ;
[max. 3] (a) insoluble + need to be converted to soluble/non-diffusible to diffusible AW ;
[max. 3] (a) to be absorbed ;
[max. 3] (a) from (small) intestine/ileum;
[max. 3] (a) into blood/capillaries/lymph/lacteals;
[max. 7] (b) bile from + liver/gall bladder/bile duct;
[max. 7] (b) ref. emulsification;
[max. 7] (b) increased surface area;
[max. 7] (b) ref. provision of optimum pH/alkaline conditions ;
[max. 7] (b) small intestine/duodenum ;
[max. 7] (b) lipase;
[max. 7] (b) from pancreas ;
[max. 7] (b) fatty acids;
[max. 7] (b) glycerol;

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