Biology · May / June 2023 · Paper 41 · Question 1

K ;

C ;

K ;

H ;

H ;

any four from:

pH decreases / (solution) becomes acidic ;

(pH changes because) fatty acids are produced ;

lipase, digests / breaks down, fat ;

fatty acids, produced / AW, faster in test-tube C than B ;

bile, emulsifies fats / converts large particles of fat to small particles ; bile increases the surface area (for lipase action) ;

compare with tubes B and C to assess effect of lipase and / or bile ; shows that bile, does not (chemically) digest fats / does not make solution acidic ;

shows that, lipase / enzyme, is required (for breakdown of fats in milk) ;

line drawn showing that decrease after optimum is steeper than increase ;

MP1 - line does not have to start at the origin or end at the x-axis label line to point where line meets the x-axis and label indicating that all the lipase is denatured / AW ;

MP2 – line must meet the x-axis

any three from:

ref to specificity ;

(only) substrate for lipase is fat (molecules) ;

shape of active site is, not complementary to protein / complementary to fat ;

protein cannot, fit into / bind to, active site / lipase / enzyme ; enzyme-substrate complexes cannot be formed ;