| Date | November 2018 | Marks available | 2 | Reference code | 18N.3.sl.TZ0.15 |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Outline | Question number | 15 | Adapted from | N/A |
Question
Viruses and bacteria both cause diseases and are frequently confused.
State one way in which viruses differ from bacteria.
Outline two different ways in which antiviral medications work.
Markscheme
bacteria perform living functions «on their own and viruses do not without host cell»
OR
bacteria have cell walls «and viruses do not»
OR
bacteria do not have a capsid «and viruses do»
OR
bacteria larger than viruses
OR
bacteria reproduce by fission/budding «and viruses reproduce within a living host cell»
OR
bacteria affected by antibiotics «while viruses are not» ✔
Accept “bacteria have flagella/ cytoplasm/ribosome «and virus can have head/protein tail/double stranded RNA/single stranded DNA»”, “asexual reproduction for bacteria”, other specific structural differences between bacteria and viruses, and examples of living functions that bacteria perform (such as excretion, reproduction etc.) that viruses do not.
Any two of:
prevents virus attaching to host cell ✔
alters cell’s genetic material/DNA «so that virus cannot use it to multiply» ✔
blocks enzyme activity in the host cell «so that virus cannot use it to multiply» ✔
prevents removal of protein coat/capsid ✔
prevents injection of viral DNA/RNA into cell ✔
prevents release of «replicated» viruses from host cell ✔
Accept “prevents synthesis of virus by host cell”.
Accept “alters RNA/DNA/genetic material of virus”.
Do not accept just “mimics nucleotides”.
Examiners report
Syllabus sections
- 17N.3.sl.TZ0.19b: Explain how oseltamivir and zanamivir can stop the spread of the flu virus in the body.
- 16N.3.sl.TZ0.17a: Zanamivir must be taken by inhalation, not orally. Deduce what this suggests about the...
- 18N.3.hl.TZ0.19: Outline two different ways in which antiviral medications work.
-
17M.3.sl.TZ1.21a:
Outline how oseltamivir (Tamiflu®) works.
-
19M.3.sl.TZ1.17a(i):
Draw a circle around the functional group that can be converted to the carboxylate by hydrolysis.
-
18M.3.sl.TZ2.19a:
Identify the names of two functional groups present in zanamivir using section 37 of the data booklet.
-
17N.3.sl.TZ0.19a:
State the names of two functional groups that both compounds contain, using section 37 of the data booklet.
-
18M.3.sl.TZ1.15a:
Oseltamivir (Tamiflu) and zanamivir (Relenza) are used against flu viruses. Explain how these drugs function.
- 19N.3.hl.TZ0.25d: Discuss two difficulties, apart from socio-economic factors, associated with finding a cure...
-
19M.3.sl.TZ2.17a:
Outline one way in which antiviral drugs work.
-
19M.3.sl.TZ1.17b:
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.
-
18N.3.sl.TZ0.15a:
State one way in which viruses differ from bacteria.
- 19N.3.sl.TZ0.18b: Discuss two difficulties, apart from socio-economic factors, associated with finding a cure...
-
19M.3.hl.TZ1.22a(i):
Draw a circle around the functional group that can be converted to the carboxylate by hydrolysis.
-
19M.3.hl.TZ2.24b:
Discuss two difficulties associated with solving the AIDS problem.
-
18M.3.sl.TZ2.19b:
Distinguish between bacteria and viruses.
-
16N.3.sl.TZ0.16b:
(i) Some antibiotic-resistant bacteria produce a beta-lactamase enzyme which destroys penicillin activity. Suggest how adding clavulanic acid to penicillin enables the antibiotic to retain its activity.
(ii) Populations of antibiotic-resistant bacteria have increased significantly over the last 60 years. Outline why antibiotics such as penicillin should not be prescribed to people suffering from a viral infection.
-
19M.3.hl.TZ1.22c:
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.
-
19M.3.hl.TZ2.24a:
Outline one way in which antiviral drugs work.
-
19N.3.sl.TZ0.18a:
State one difference between bacteria and viruses.
- 20N.3.sl.TZ0.14a(i): Name two functional groups that both zanamivir and oseltamivir contain.
-
20N.3.sl.TZ0.14a(ii):
Explain how zanamivir works as a preventative agent against flu viruses.
-
19M.3.sl.TZ2.17b:
Discuss two difficulties associated with solving the AIDS problem.
-
20N.3.hl.TZ0.19a:
Explain how zanamivir works as a preventative agent against flu viruses.
