Question 21M.2.HL.TZ2.3a
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.2.HL.TZ2.3a |
| Level | HL | Paper | 2 | Time zone | TZ2 |
| Command term | State | Question number | a | Adapted from | N/A |
State one function of Rubisco.
[1]
a. enzyme involved in photosynthesis/carbon fixation/Calvin cycle
OR
speeds up chemical reactions in photosynthesis ✔
b. carboxylation of RuBP ✔
c. production of carbohydrate in photosynthesis ✔
d. addition of carbon dioxide to form glucose (in Calvin cycle) ✔
Either photosynthesis or carbon fixation must be mentioned.
There were some G2 comments about the function of Rubisco. It is mentioned in 2.4. and the stem did say that it was an enzyme. Simply stating that it was an enzyme involved in photosynthesis was sufficient for the mark. A detailed function was not required. Most could state the role of the active site and that the genus was Pisume. The word genus in this context confused some French candidates who answered 'male or female'. 3(d) was simply testing the factors controlling enzyme action. Weaker students just listed several factors. When it says one factor, only the first is considered. The difference between heat and temperature was occasionally confused. The examiners were looking for the effect of increasing and decreasing the factor. Many students seemed to be obsessed with denaturing. For example the answer 'temperature' (first mark): as the temperature is too high the enzyme denatures (no second mark as no mention of decreasing temperature). Few used the collision theory idea which was expected.
