Biology · Oct / Nov 2021 · Paper 41 · Question 4

bacteria ;

any one from:

weakened / dead / AW, bacteria / pathogen ;

antigen(s) (of the pathogen) ;

AVP ;

any three from:

idea that the immune response takes time to occur ;

lymphocytes release antibodies ;

ref. to (lymphocytes) produce specific antibodies to the (cholera) antigens / AW ;

memory cells (form) ;

long-term immunity ;

idea that they did not have (active) immunity / memory cells before the start of the study / AW ;

any two from:

more, pathogens / diarrhoea / fever, in non-vaccinated group ; ora some vaccinated people did get symptoms so vaccine not 100% effective ; ora

comparative data quote between vaccinated and not vaccinated ; AVP ;

any four from:

cholera / pathogen, releases toxin ;

(toxin) causes (more) chloride released (into small intestine) ; lowering water potential (in lumen) ;

ref. to, osmosis / movement of water (into the lumen) ;

(diarrhoea is) loss of watery faeces ;

loss of salts / loss of minerals / dehydration ;

any two from:

oral rehydration therapy ;

drink mixture of, sugar / nutrients and, salt / ions ;

replace lost, water / fluids ;

AVP ;