Question 18N.3.sl.TZ0.6
| Date | November 2018 | Marks available | [Maximum mark: 6] | Reference code | 18N.3.sl.TZ0.6 |
| Level | sl | Paper | 3 | Time zone | TZ0 |
| Command term | Describe, Explain, Outline | Question number | 6 | Adapted from | N/A |
Enzymes are mainly globular proteins.
Describe the interaction responsible for the secondary structure of a protein.
[2]
hydrogen bonding ✔
between C=O and H–N «groups» ✔
Accept a diagram which shows hydrogen bonding for M1 and which shows the interaction between O of C=O and H of NH groups for M2.
Accept “between amido/amide/carboxamide” but not “between amino/amine” for M2.
Explain the action of an enzyme and state one of its limitations.
[3]
Enzyme action:
Any two of:
substrate binds to active site ✔
weakens bonds in substrate ✔
lowers activation energy
OR
provides alternate pathway ✔
increases rate of reaction
OR
acts as catalyst ✔
substrate specific ✔
Limitation:
Any one of:
temperature dependent ✔
pH dependent ✔
can be sensitive to heavy metal ions ✔
sensitive to denaturation ✔
can be inhibited ✔
substrate specific ✔
Accept “favourable orientation/conformation of the substrate «enforced by enzyme»” for M1.
Do not accept “substrate specific” as both an enzyme action and a limitation.
Enzymes are widely used in washing detergents. Outline how they improve the efficiency of the process.
[1]
Any one of:
«increase rate of» hydrolyse/break down lipids/oils/fats/proteins ✔
«wash at» lower temperature/consume less energy ✔
