Question 23M.3.SL.TZ1.14
| Date | May 2023 | Marks available | [Maximum mark: 5] | Reference code | 23M.3.SL.TZ1.14 |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Describe, Explain, Suggest | Question number | 14 | Adapted from | N/A |
Many illnesses are caused by bacteria and viruses.
Describe how viruses differ from bacteria.
[1]
viruses have no nucleus but bacteria do
OR
viruses have no organelles but bacteria do
OR
viruses cannot perform biological functions/reproduce without a host but bacteria can
OR
viruses are not cells but bacteria are
OR
viruses are smaller than bacteria ✓
Accept specific structural differences. Such as “bacteria have cytoplasm/ribosomes but viruses do not" or "viruses can have double stranded RNA/single stranded DNA whereas bacteria always have double stranded DNA".
Do not accept “Bacteria are living and viruses are not”.
Explain two ways antiviral medications prevent the replication of viruses.
[2]
Any two of:
«bind to receptors to» prevent virus entering cell ✓
alter genetic material of cell/cytoplasm «to prevent replication» ✓
block enzyme activity in cell «to prevent replication» ✓
prevent virus leaving cell «by inhibiting viral enzyme/neuraminidase» ✓
Bacterial infections are treated using antibiotics such as penicillin. Suggest how penicillin can be modified and the reasons for the modification.
[2]
side chain modified ✓
overcome antibiotic resistance/ penicillinase ineffective ✓
Accept R group instead of side chain.
Accept increase the stability of penicillin in GIT/gastrointestinal tract for M2.