| Date | May 2012 | Marks available | 1 | Reference code | 12M.1.SL.TZ1.13 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Identify | Question number | 13 | Adapted from | N/A |
Question
The sequence of the first six amino acids of the normal β hemoglobin (HbA) chain are listed.
valine – histidine – leucine – threonine – proline – glutamic acid
Which sequence of amino acids could there be in the first six amino acids of the sickle-cell β hemoglobin (HbS) chain?
A. glutamic acid – histidine – leucine – threonine – proline – valine
B. valine – valine – histidine – leucine – threonine – proline
C. glutamic acid – histidine – leucine – threonine – proline – glutamic acid
D. valine – histidine – leucine – threonine – proline – valine
Markscheme
D
Examiners report
This question was perhaps not as fair as it could have been, as it did require candidates to remember difficult details about specific amino acid sequences. However, it was the fourth most difficult question on the paper, and it did discriminate well.
