| Date | November 2015 | Marks available | 1 | Reference code | 15N.1.HL.TZ0.12 |
| Level | Higher level | Paper | Paper 1 | Time zone | TZ0 |
| Command term | Question number | 12 | Adapted from | N/A |
Question
What is the chromosome number in a human gamete with non-disjunction?
A. 46
B. 45
C. 24
D. 23
Markscheme
C
Examiners report
Although most good candidates answered this question well, some candidates had different number of chromosomes in a disjunction. Unlike what happens in plants, the probability of having more than one chromosome suffering non-disjunction in humans in very low, let alone the whole set of chromosomes.
