| Date | November 2013 | Marks available | 1 | Reference code | 13N.1.SL.TZ0.9 |
| Level | Standard level | Paper | Paper 1 | Time zone | TZ0 |
| Command term | Question number | 9 | Adapted from | N/A |
Question
In enzyme experiments, the rate of enzyme activity often gradually decreases. What is most likely to cause this decrease?
A. The temperature decreasing
B. The enzyme concentration decreasing
C. The pH decreasing
D. The substrate concentration decreasing
Markscheme
D
Examiners report
There were comments on the G2s that there was more than one possible answer to this question. While it may be true that in some specific cases the various distracters may be correct, the most correct answer is D as the substrate will decrease in all enzyme reactions, causing the enzyme activity to gradually decrease.
