Question 23M.1.SL.TZ1.17
| Date | May 2023 | Marks available | [Maximum mark: 1] | Reference code | 23M.1.SL.TZ1.17 |
| Level | SL | Paper | 1 | Time zone | TZ1 |
| Command term | Question number | 17 | Adapted from | N/A |
Dolly the sheep was the first mammal to be cloned from an adult somatic cell.
[Source: Squidonius, Public domain, via Wikimedia Commons.
https://commons.wikimedia.org/wiki/File:Dolly_clone.svg.]
Which DNA did Dolly inherit?
A. Nuclear and mitochondrial DNA from the surrogate ewe
B. Nuclear and mitochondrial DNA from the Finn-Dorset
C. Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the Finn-Dorset
D. Mitochondrial DNA from the Scottish Blackface and nuclear DNA from the surrogate ewe
[1]
C
SL:
Two thirds of candidates answered correctly but there were problems with both the diagram and the answers. This question also appeared as question in 13 for HL students and further comments are made below.
HL:
There were problems with this question. Teachers correctly commented on G2 forms that the part of the diagram showing the production of an enucleated egg cell was confusing. Despite this, it was possible to deduce that the nucleus in the fused cell came from the Finn-Dorset sheep, so answers A and D were incorrect. To choose between answers B and C, candidates had to decide whether mitochondrial DNA came from the enucleated egg cell or the mammary gland cell. Research has shown that the mitochondrial DNA is from the enucleated egg cell. However, it was not possible to deduce this from the diagrams and the pattern of answers showed that some of the stronger candidates had chosen answer B (mitochondrial DNA from the mammary gland cell), so both answers B and C were accepted.