DP Biology (last assessment 2024)
Question 23M.3.SL.TZ1.3
| Date | May 2023 | Marks available | [Maximum mark: 4] | Reference code | 23M.3.SL.TZ1.3 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Deduce, State | Question number | 3 | Adapted from | N/A |
3.
[Maximum mark: 4]
23M.3.SL.TZ1.3
DNA samples of a child, his mother and three males were studied in order to determine paternity. The diagram is a simplified version of the DNA profiles obtained in the study.
(a)
State
(a.i)
where the DNA of each individual could be taken from.
[1]
Markscheme
from blood sample/hair/cheek/saliva/semen;
Do not accept red blood cells
Examiners report
Most candidates gave several answers, of which usually more than one was correct.
(a.ii)
how the DNA is amplified.
[1]
Markscheme
PCR/polymerase chain reaction
OR
using Taq polymerase;
Examiners report
The majority referred to gel electrophoresis rather than PCR. A few stated taq polymerase.
(b)
Deduce with a reason the identity of the father.
[2]
Markscheme
- male 2;
- each band in the child’s DNA must be the same as a band in either the mother or the father
OR
any band in the child’s profile that is not present in the mother’s profile must be present in the father’s;
Must mention both the mother and father
Examiners report
Nearly all candidates identified male 2 but fewer referred to the mother's bands.
