| Date | May 2019 | Marks available | 1 | Reference code | 19M.1.SL.TZ2.13 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Deduce | Question number | 13 | Adapted from | N/A |
Question
The graph shows the incidence of trisomy resulting from non-disjunction in pregnancies at different maternal ages.
[Source: Center for Disease Control]
What can be inferred from the graph?
A. The incidence of three copies of a chromosome increases directly in proportion with the age of the mother.
B. The incidence of three sets of chromosomes increases from age 20.
C. The incidence of three copies of a chromosome increases the most from age 35.
D. The incidence of three sets of chromosomes increases the most from age 30.
Markscheme
C
Examiners report
This question was in badly answered by the most capable candidates and therefore discriminated very badly. Unfortunately, candidates confused the words sets and copies. Some candidates believed the increase was proportionate, failing to realize a straight line should have been drawn if this was the case.
