Biology 9700 · AS & A Level · Transport mechanisms

Transport mechanisms — practice question

Fig. 2.1 depicts the disaccharide lactose, which occurs in milk.
(a)[1]

Name the bond type that links the two monosaccharides in lactose.

(b(i))[1]

The enzyme lactase catalyses the splitting of the bond between the two monosaccharides in lactose. Name the reaction type that breaks this bond.

(b(ii))[2]

Some people do not make the enzyme lactase, so they cannot digest lactose. Lactose in the intestinal lumen lowers the amount of water absorbed into the blood, causing diarrhoea. Suggest why lactose in the intestine reduces the amount of water absorbed.

(c(i))[2]

Suggest the benefit of using small beads instead of large ones.

(c(ii))[3]

With reference to Fig. 2.2, compare how temperature affects the activity of immobilised lactase, I, and lactase free in solution, F.

(c)[3]

Using Fig. 2.2, compare the effect of temperature on the activity of immobilised lactase, I, and lactase free in solution, F.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: A glycosidic bond, for example $\beta$-$1,4$

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