DP Chemistry (last assessment 2024)
Question 19M.3.hl.TZ1.22c
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ1.22c |
| Level | hl | Paper | 3 | Time zone | TZ1 |
| Command term | Explain | Question number | c | Adapted from | N/A |
c.
[Maximum mark: 2]
19M.3.hl.TZ1.22c
This question is about antiviral drugs.
(c)
Anti-HIV drugs, such as zidovudine, often become less effective over time.
Explain the development of resistant virus strains in the presence of antiviral drugs.
[2]
Markscheme
viruses undergo «rapid» mutation [✔]
mutation causes a change in viral protein
OR
drug no longer binds to virus [✔]
Note: Accept “rapid reproduction «allows resistant viruses to multiply»”.
Examiners report
Most candidates scored the first marking point when explaining the development of resistant virus strains but almost no-one scored the second mark. Many candidates were confused between bacteria and viruses and gave explanations about bacterial resistance and natural selection.
