Biology · May / June 2024 · Paper 41 · Question 6

– 64 (%) / 64 (%) decrease ;;;

any five from:

1

(vaccination confers) active immunity ;

2

(vaccine contains) weakened / inactivated / dead / AW, virus / pathogen ; 3

(vaccine) stimulates (primary) immune response ;

4

lymphocytes produce antibodies ;

5

antibodies, destroy / agglutinate / immobilise / kill, virus / pathogen ; 6

antibodies, mark / attached to, virus / pathogen, so phagocytes destroy them ;

7

production of memory cells ;

8

long-term immunity / AW ;

9

herd immunity / protecting unvaccinated people ;

10 person to person transmission interrupted / prevents the spread of polio through the population / AW ;

11 AVP ;

any two from:

ref. to specificity (in context of antigen or antibody) ;

antibodies (produced in response to the polio vaccine) have a complementary shape only to polio antigens ;

antibodies bind only to polio virus ;

idea that memory cells (produced by polio vaccine) are not activated by other pathogens ;

AVP ;

total of three from:

(blood clot / scab) prevents entry of pathogens / pathogens trapped in mesh / (blood clot / scab) is a barrier to pathogens ;

max two from:

conversion of fibrinogen to fibrin ;

conversion of soluble (protein) to, insoluble / fibrous (protein) ;

forms, network of fibres / mesh ;

ref to role of platelets ;

formation of a scab ;

plasma ;