| Date | May 2017 | Marks available | 1 | Reference code | 17M.2.HL.TZ2.2 |
| Level | Higher level | Paper | Paper 2 | Time zone | Time zone 2 |
| Command term | Describe | Question number | 2 | Adapted from | N/A |
Question
The enzyme ATP synthase has an essential role in aerobic cell respiration.
The sketch shows the relationship between the reaction rate and substrate concentration in the presence and the absence of a competitive inhibitor.
Explain the effect of the competitive inhibitor on the reaction rate.
Describe its location.
Describe its function.
Markscheme
a. competitive inhibitor «slows the reaction rate as it» competes for the active site
OR
competitor has similar shape/structure/composition to substrate «and slows the reaction rate»
b. binding of competitor is reversible
c. «as the substrate concentration increases» more substrate binds to the active site than the competitor «and reaction rate increases»
d. «as the substrate concentration increases» the reaction rate reaches the maximum plateau «same as with no inhibitor»
the inner mitochondrial membrane critstae/thylakoid membrane
a. protons build up in the intermembrane space due to electron transport chain OWTTE
b. protons move through ATP synthase down the concentration gradient
Accept H+ ions in place of protons
c. catalyses formation of ATP OWTTE
