DP Biology (last assessment 2024)
Question 19M.2.HL.TZ1.c.i
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.HL.TZ1.c.i |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Identify | Question number | c.i | Adapted from | N/A |
c.i.
[Maximum mark: 1]
19M.2.HL.TZ1.c.i
The karyogram shown is for the African marsh rat (Dasymys incomtus). In this species, sex is determined by X and Y chromosomes. Females are XX and males are XY.
[Source: adapted from https://embryology.med.unsw.edu.au]
Identify, with a reason, the sex of this individual.
[1]
Markscheme
male because «X and» Y chromosome present
OR
male because sex chromosomes/last two chromosomes/pair 21 are unpaired/different «from each other»/not homologous ✔
The answer must include “male” and the reason.
Examiners report
90 % of candidates correctly identified the individual as male, because the two sex chromosomes were different in size so must be an X and a Y. The other 10% mostly thought that there were two X chromosomes present, perhaps because pair 20 were X shaped.
