DP Chemistry (last assessment 2024)
Question 19M.3.hl.TZ1.12a(ii)
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ1.12a(ii) |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Suggest | Question number | a(ii) | Adapted from | N/A |
a(ii).
[Maximum mark: 2]
19M.3.hl.TZ1.12a(ii)
Alcohol dehydrogenase (ADH) catalyses the oxidation of methanol. The products of oxidation, methanal and methanoic acid, are toxic.
(a(ii))
Suggest, based on the Michaelis–Menten plot, how a competitive inhibitor such as ethanol reduces the toxicity of methanol.
[2]
Markscheme
Km is higher /same Vmax reached at higher [substrate] [✔]
slower reaction rate
OR
gives time to excrete/eliminate methanol [✔]
Examiners report
Many scored 1 out of 2 for stating that the inhibitor causes a slower reaction rate.
