CAIE IGCSE Biology 7.4.1 Definition of Chemical Digestion

Practise defining chemical digestion as converting large insoluble food molecules into small soluble molecules, then distinguish enzyme action from churning or grinding.

Exam points

define chemical digestion as breaking large insoluble molecules into small soluble molecules
identify starch-to-reducing-sugar breakdown as chemical rather than physical digestion
explain why large insoluble starch cannot cross the intestinal epithelium before digestion

[Maximum number: 2]

Fig. 1.1 shows the movement of particles through an epithelial cell in the small intestine.

Fig. 1.1

In Fig. 1.1, particle R moves from the lumen of the small intestine into the epithelial cell.

Suggest why particle R cannot be starch.

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7.4.1—Chemical digestion as the breakdown question 1