| Date | May 2010 | Marks available | 1 | Reference code | 10M.1.SL.TZ1.11 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Label | Question number | 11 | Adapted from | N/A |
Question
The following diagram shows a short stretch of DNA. What bases are indicated by labels Y and Z?
Markscheme
B
Examiners report
There was a mistake in the diagram, as adenine is shown joined by three hydrogen bonds to thymine and cytosine by two hydrogen bonds to guanine when it should have been the other way round. Nevertheless, the usefulness of the question was not affected, as most candidates answered this question correctly.
