| Date | November 2010 | Marks available | 1 | Reference code | 10N.2.HL.TZ0.3 |
| Level | Higher level | Paper | Paper 2 | Time zone | TZ0 |
| Command term | Define | Question number | 3 | Adapted from | N/A |
Question
Define the term passive immunity.
State one use of monoclonal antibodies in diagnosis.
Define the term pathogen.
Outline why antibiotics are effective against bacteria but not against viruses.
Markscheme
the acquisition of antibodies from another organism
An example, e.g. detection of (antibodies to) HIV (reject AIDS) / isoenzyme in heart attack / (HCG in) pregnancy test kits / blood and tissue typing / detection of malarial parasites
Accept any other valid examples.
an organism/virus that causes a disease
a. antibiotics block/inhibit specific metabolic pathways/cell functions found in bacteria;
Accept specific examples of inhibition such as cell protein synthesis, cell wall formation.
b. viruses must use host/eukaryotic cell metabolism / viruses do not have their own metabolic pathways;
c. host/eukaryotic cell metabolism/pathways not blocked/inhibited by antibiotics;
Examiners report
The two definitions of passive immunity and pathogen were quite well known.
The topic of monoclonal antibodies was very centre specific, with some centres missing it out of their schemes of work.
The effectiveness of antibodies against bacteria due to specific metabolic inhibition, as opposed to viruses (or their hosts), whose metabolism is not inhibited was not always fully understood.
