| Date | May 2012 | Marks available | 1 | Reference code | 12M.1.HL.TZ1.8 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 8 | Adapted from | N/A |
Question
What occurs during DNA replication?
A. DNA polymerase separates the two DNA strands.
B. DNA molecules containing nucleotides from the original molecule are produced.
C. Adenine forms a base pair with either thymine or uracil.
D. New bases attach to the original sugar-phosphate backbone.
Markscheme
B
Examiners report
Question 8 was answered relatively poorly by candidates. There was a concern expressed by some teachers that C was a correct answer because RNA primers formed during DNA replication have uracil paired with adenine in the template DNA strand. In fact this was the least popular answer and candidates can reasonably have been expected to choose answer B as the best response. Substantial numbers of candidates chose A and D, showing weak understanding of replication.
