Question 22M.1A.HL.TZ2.29
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.1A.HL.TZ2.29 |
| Level | HL | Paper | 1A | Time zone | TZ2 |
| Command term | Question number | 29 | Adapted from | N/A |
Ethylene glycol is used as an antifreeze chemical. If a person ingests it accidentally, ethylene glycol is rapidly converted by a series of enzyme-catalysed reactions in the liver to oxalic acid, which is toxic. The diagram summarizes the steps and enzymes involved in the conversion of ethylene glycol to oxalic acid.
The production of oxalic acid can be prevented if the person drinks ethanol, a competitive inhibitor of the enzyme alcohol dehydrogenase I. Which statement explains the mode of action of ethanol on the reaction?
A. It causes end product inhibition.
B. It disrupts the shape of the active site by binding to another site on alcohol dehydrogenase I.
C. It occupies the active site of alcohol dehydrogenase I, preventing ethylene glycol from binding.
D. It binds to ethylene glycol, preventing it from fitting into the active site of alcohol dehydrogenase I.
[1]
C
Despite having a lot of text in the question stem this question was correctly answered by 85 % of the candidates.
