| Date | November 2009 | Marks available | 3 | Reference code | 09N.3.SL.TZ0.8 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Distinguish | Question number | 8 | Adapted from | N/A |
Question
Distinguish between the secondary structure and tertiary structure of proteins.
[3]
b.
Explain what is meant by allosteric inhibition.
[3]
c.
Markscheme
b.
form of non-competitive inhibition;
(inhibitor) binds to a site that is not the active site;
causing conformational change;
changes the active site;
so substrate can no longer bind to active site;
c.
Examiners report
Many candidates forgot to distinguish between the secondary and tertiary structures of proteins. This command term requires showing the differences between them, not just a description of one of them.
b.
Allosteric inhibition was well understood by a number of candidates.
c.
