Date | May 2022 | Marks available | 1 | Reference code | 22M.1.HL.TZ1.28 |
Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
Command term | Question number | 28 | Adapted from | N/A |
Question
This DNA sequence was used to synthesize a polypeptide.
DNA (sense strand): 3′ T A C T G A 5′
DNA (template strand): 5′ A T G A C T 3′
Which are the bases of the tRNA (anticodons)?
A. T A C T G A
B. U A C U G A
C. A U G A C U
D. A T G A C T
Markscheme
C
Examiners report
The discrimination index for this question was low, and as only 44 % answered correctly, the explanation was not that it was too easy. The question asked for the bases of the anticodons used to produce a polypeptide. They will be complementary to the DNA sense strand, because it will have the same base sequence (apart from T/U) as the codons of the mRNA that is translated into the polypeptide. B was almost as popular as the correct answer, but gives the codons, rather than the anticodons.