Question 18M.3.SL.TZ1.1
| Date | May 2018 | Marks available | [Maximum mark: 5] | Reference code | 18M.3.SL.TZ1.1 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe, Evaluate, Identify | Question number | 1 | Adapted from | N/A |
A study was carried out on the activity of catalase in bacteria living in extreme environments. Catalase decomposes hydrogen peroxide (H2O2). The data were obtained for a strain of bacteria called Vibrio rumoiensis which exhibits high catalase activity.
Describe the relationship between increasing H2O2 concentration and catalase activity.
[2]
a. as H2O2 concentration increases catalase activity increases / positive correlation
(up to 70 mM)
b. peak activity at approximately 70 mM
c. activity decreases after the peak
Identify two factors that would need to be controlled in generating these data.
[1]
temperature / pH / enzyme concentration / enzyme volume / quantity of bacteria
2 answers for 1 mark.
Evaluate the claim that, based on the data, the optimum H2O2 concentration for catalase is 70 mM.
[2]
a. maximum peak / optimum around 70 mM
b. but overlapping error bars around 70 mM
c. no clear optimum / range between 60 − 90 mM
d. may only be true for this strain Vibrio rumoiensis / other variables not reported (e.g. another form of catalase)