Biology · May / June 2022 · Paper 41 · Question 1

Fungus / Fungi ;

aerobic respiration ;

any two from:

ref. to specificity (of enyme) ;

shape of active site is complementary to, substrate / sucrose ;

for, substrate / sucrose, to bind / fit, enzyme / sucrase / active site ;

total of six from:

max. four for description:

1

sucrase / enzyme, is active between pH2 and pH12 ;

2

activity, increases and decreases / reaches a peak ;

3

peak / maximum or 100% activity, at pH 6 ;

4

steeper increase between pH 5–6 / steeper decrease in activity between pH 9–10 ;

5

minimum / 10%, activity at pH 12 ;

6

more activity in, acidic conditions / low pH, than, alkaline

conditions / high pH ;

explanation:

7

(change in) pH affects the shape of, sucrase / active site / enzyme ; 8

at pH 6, most enzyme-substrate complexes form / AW ;

9

at, low / high / extremes of, pH, enzyme is (partially) denatured ; 10 ref to substrate molecules can no longer bind with enzyme (at low / high / extreme pH, so activity decreases) ;

11 AVP ;