Biology · May / June 2020 · Paper 41 · Question 5

any two from:

assume features are of protoctists unless told otherwise

nucleus / nuclear membrane / nuclear envelope ;

(named) organelle(s) / internal membranes ;

cell walls (if present) have different composition ;

linear chromosomes ;

AVP ;

box 2: (organism) has two rings of cilia / (organism) stalk absent / AVP ;

box 4: (organism) has a covering of cilia / (organism) fused cilia absent / AVP ;

movement AND nutrition ticked ;

bacteria Paramecium Didinium ;

any two from:

ciliates eat (many) bacteria ;

Didinium / predatory ciliates, eat other (named) ciliates ;

ciliates may eat, dead / decomposing, material ;

any three from:

removal of, harmful bacteria /pathogens, from sewage ;

e.g. cholera bacteria or any other water born disease / parasites ;

stop spread of pathogens via water ;

use of chlorination / chemical treatment ;

any three from:

conversion of ammonia / ammonium (ions), to nitrate (ions) ;

convert ammonium ions to nitrite ions ;

make nitrate ions available to plants ;

nitrate ions are absorbed by plants ;

nitrate ions are used to make, amino acids / proteins ;