Date | November 2018 | Marks available | 1 | Reference code | 18N.3.sl.TZ0.6 |
Level | SL | Paper | 3 | Time zone | TZ0 |
Command term | Outline | Question number | 6 | Adapted from | N/A |
Question
Enzymes are mainly globular proteins.
Describe the interaction responsible for the secondary structure of a protein.
Explain the action of an enzyme and state one of its limitations.
Enzymes are widely used in washing detergents. Outline how they improve the efficiency of the process.
Markscheme
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.
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.
Any one of:
«increase rate of» hydrolyse/break down lipids/oils/fats/proteins ✔
«wash at» lower temperature/consume less energy ✔