Date | May 2021 | Marks available | 1 | Reference code | 21M.1.HL.TZ2.28 |
Level | Higher level | Paper | Paper 1 | Time zone | Time zone 2 |
Command term | Question number | 28 | Adapted from | N/A |
Question
The mRNA codon UAC codes for the amino acid tyrosine. Which tRNA carries tyrosine?
Markscheme
B
Examiners report
The G2 forms raised two concerns with this question.
Firstly, the use of the term codon to describe a DNA sequence of 3 bases when this term is normally used for sequences of bases on mRNA. It is normal to use the term triplet referring to bases on a strand of DNA though codon is an accepted but infrequently used alternative.
Secondly, the question does not make it clear if it is referring to the sense or antisense strand, both of which would give different responses.
Both answers C and D were accepted as correct, and the question will be changed before the paper is published.