Biology · May / June 2022 · Paper 41 · Question 4

any five from:

1

protein, broken down / digested / decomposed, to amino acids ; 2

by decomposers / fungi / bacteria in terms (in context of breakdown of manure / protein) ;

3

ref to use of proteases ;

4

deamination (of amino acids / proteins) / described ;

5

production of, ammonia / ammonium ions / NH3 / NH4+ ;

6

ammonium (ions), converted to, nitrite / nitrate (ions) / NO3-/ NO2-; 7

ref. to, nitrification / nitrifying bacteria ;

8

AVP ; e.g., nitrite to nitrate ions

any one from:

farmers, do not have to add (nitrogen) fertiliser / use less fertiliser ; idea of increased yield / more profit per hectare ;

(snap beans / beans / plants) grow, faster / better ;

63 (%) ;;;

any four from:

1

breakdown / decomposition, of manure / AW ;

2

increase in (availability of named), ions (in streams/rivers) ; 3

(increased) growth of, (named) plants / producers / algae ; 4

increased competition for, light / AW ;

5

no photosynthesis causing death of, producers / plants / algae ; 6

increase in, (number of) bacteria / decomposers ;

7

respiration (by decomposers) reduces (dissolved) oxygen (leads to death of fish) ;