Question 18M.2.SL.TZ2.4
| Date | May 2018 | Marks available | [Maximum mark: 5] | Reference code | 18M.2.SL.TZ2.4 |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain, Sketch | Question number | 4 | Adapted from | N/A |
Sketch a graph to show the effect of temperature on the activity of enzymes.
[2]
a. axes labelled correctly: x-axis as temperature AND y-axis as rate of reaction/enzyme activity
b. correct shape of graph: increases gradually to max and then decreases more rapidly
Fall should be at least twice as steep as rise.
Explain enzyme–substrate specificity.
[3]
a. enzymes are proteins with specific 3-D geometry/shape
b. enzymes with active site that binds with the substrate/reactants
c. active site shape only allows it to bind with specific substrates «with complementary shapes»
d. when enzyme-substrate complex formed allows reaction to occur
e. products are released and enzyme returns to original shape and can be reused
OR
denaturing changes shape «of active site» so changes ability to bind with substrate
Accept marks from clear annotated diagrams.
