Question 22N.2.SL.TZ0.3
| Date | November 2022 | Marks available | [Maximum mark: 4] | Reference code | 22N.2.SL.TZ0.3 |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Draw, Explain, State | Question number | 3 | Adapted from | N/A |
The diagram shows the molecular structure of the amino acid leucine.
Draw a circle on the diagram to enclose the carboxyl group.
[1]
No mark if C1 in chain is included.
The carboxyl group was not well known in (a). In b, the classic answers of insulin or glucagon were expected, but a disturbing number gave answers that were neither proteins nor hormones. In (c) most were able to gain a mark for the enzyme lactase, and either the products of digestion or the fact that the enzyme is immobilised. Weaker candidates tried to explain lactose intolerance instead of answering the question.
State one protein that acts as a hormone.
[1]
insulin/glucagon/ADH/oxytocin/leptin / other verified example;
Explain how enzymes are used in the preparation of milk suitable for individuals who are lactose intolerant.
[2]
- the enzyme lactase acts on lactose;
- the enzymes are immobilised / are bound to alginate beads;
- (pouring milk over the immobilised enzymes) causes lactose to be hydrolysed/broken down into monosaccharides/glucose and galactose;
Some product must be stated in mpc.
