Question 19M.3.hl.TZ1.20
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.3.hl.TZ1.20 |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Identify, Outline | Question number | 20 | Adapted from | N/A |
Staphylococcus aureus (S. aureus) infections have been successfully treated with penicillin and penicillin derivatives.
Identify the feature in penicillin responsible for its antibiotic activity.
[1]
«four-membered» beta-lactam ring [✔]
Note: Accept a diagram showing a structural representation of the beta-lactam ring.
Most candidates correctly identified the feature in penicillin responsible for its antibiotic activity.
The widespread use of penicillin and its derivatives has led to the appearance of resistant S. aureus strains.
Outline how these bacteria inactivate the antibiotics.
[1]
produce penicillinase/enzyme that deactivates penicillin [✔]
Most candidates could outline how bacteria inactivate the antibiotics.
Outline how the structure of penicillin has been modified to overcome this resistance.
[1]
side-chain changed «preserving beta-lactam ring» [✔]
Note: Accept “R group changed”.
Outlining how the structure of penicillin has been modified was less well answered, with many candidates referring to functional groups rather than the side chain or R group.