DP Biology (last assessment 2024)
Question 20N.3.SL.TZ0.a
| Date | November 2020 | Marks available | [Maximum mark: 1] | Reference code | 20N.3.SL.TZ0.a |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Label | Question number | a | Adapted from | N/A |
a.
[Maximum mark: 1]
20N.3.SL.TZ0.a
The cladogram shows where mutations probably occurred in ancestral lines resulting in some animal species being unable to produce ascorbic acid (vitamin C).
[Source: Drouin, G., Godin, J.-R. and Pagé, B., 2011. The Genetics of Vitamin C Loss in Vertebrates. Current
Genomics, 12(5), pp.371–378.]
On the cladogram, label with an M, the point at which a mutation occurred, preventing the gibbon from synthesizing ascorbic acid.
[1]
Markscheme
Examiners report
Most candidates could label the correct point on the cladogram where a mutation occurred and state the reason ascorbic acid is described as an essential nutrient.
