Question 19N.3.SL.TZ0.2
| Date | November 2019 | Marks available | [Maximum mark: 3] | Reference code | 19N.3.SL.TZ0.2 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Outline, State | Question number | 2 | Adapted from | N/A |
The enzyme beta-galactosidase hydrolyses lactose to release glucose and fructose. A study was carried out to determine how acidity affects the activity of a beta-galactosidase enzyme, extracted from the fungus Penicillium simplicissimum.
[Source: Cruz R, et al. Properties of a new fungal β-galactosidase with potential application in the dairy industry.
Revista de Microbiologia 30: 265–271, 1999]
State another independent variable that would affect the activity of this enzyme.
[1]
temperature
OR
lactose/substrate concentration
OR
Inhibitors / cofactors ✔
Do not accept pH or acidity.
Outline the measurements which would need to be taken to determine the activity of the beta-galactosidase at different pH values.
[2]
a. test samples for the concentration/amount of products/glucose/fructose/substrate/lactose ✔ Accept use Benedict/Fehling to see change in amount of reducing sugar
b. take samples of the reaction mixture at regular/timed intervals ✔ Must indicate that samples are taken at timed intervals
c. repeated measurements «at the different pH values» ✔
d. measure independent/controlled/standardised/variables / temperature ✔
