| Date | May 2012 | Marks available | 1 | Reference code | 12M.1.HL.TZ1.11 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Identify | Question number | 11 | 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
Question 11 was not popular with some teachers. Like question 7, it was felt to depend solely on a memorised fact, in this case the specific mutation that causes sickle cell anemia. This knowledge is specified by the programme, so could have been expected, but ideally answer C should have been slightly different so that it could have been eliminated using understanding.
