Biology · Oct / Nov 2021 · Paper 42 · Question 5

any two from:

water / fluid / liquid, intake ;

exercise / activity level ;

sweating ;

temperature ;

salt / salty food, intake ;

quantity of urea produced / concentration of urea in blood ;

(named) drug ;

(named) medical condition ;

AVP ; e.g. water potential of blood / AW

any five from:

1

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

ammonification / mineralisation ;

3

amino acids converted to, ammonium (ions) / NH4+ ;

4

by, decomposers / fungi / bacteria ; if linked to MP1, MP2 or MP3 5

ammonium (ions) / NH4+, converted / oxidised to, nitrate (ions) / NO3– ; 6

nitrification / nitrifying bacteria ;

7

plants, absorb / use, nitrate (ions) (and ammonium ions) ;

8

AVP ; e.g. deamination of amino acids

any six from:

1

eutrophication ;

2

increased growth of, plants / producers / algae ;

3

plants / producers, compete with each other for light / AW ,

4

plants / producers, die or plants / producers, are decomposed ;

5

increase in, decomposers / bacteria ;

6

bacteria / decomposers, use / absorb, (dissolved) oxygen in water ; 7

decrease in concentration of (dissolved) oxygen ;

reasons for reduction in biodiversity:

8

death of, (named) animals / fish / invertebrates (due to lack of dissolved oxygen) ;

9

decrease in, food / energy, available in, ecosystem / AW ;

10 ref to, pathogens / disease / toxins / poisons ;

11 ref to aerobic respiration (in either section)

12 AVP ;