Question 19M.2.SL.TZ2.5c
| Date | May 2019 | Marks available | [Maximum mark: 8] | Reference code | 19M.2.SL.TZ2.5c |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | c | Adapted from | N/A |
Explain the action of enzymes in digestion and the different roles of at least two named enzymes that are produced in the pancreas.
[8]
a. enzymes catalyse/speed up chemical reactions/lower the energy needed ✔ OWTTE
b. have specific active sites to which specific substrates bind ✔
c. enzyme catalysis involves molecular motion and the collision of substrates with the active site ✔ OWTTE
d. enzymes break macromolecules into monomers/smaller molecules indigestion ✔
e. smaller molecules/monomers more readily absorbed ✔
f. <<pancreas>> secretes enzymes into the «lumen of» small intestine ✔
g. the small intestine has an alkaline pH ✔
h. enzymes have maximum action at specific pHs
OR
enzymes can be denatured at other pHs ✔
i. amylase breaks down starch into sugars/disaccharides ✔
j. lipase breaks lipids/triglycerides into monoglycerides/fatty acids and glycerol ✔
k. endopeptidase/protease breaks «peptide» bonds in proteins/polypeptides ✔
l. accept any other valid pancreatic enzyme, substrate and product ✔
Award [6 max] if there is no mention of two specific groups of enzymes.
Enzymes in digestion. A disturbing number of candidates saw the word pancreas and wrote about insulin and glucagon. These are hormones, produced by ENdocrine glands not enzymes produced by EXocrine glands. Better candidates scored nearly full marks, by describing enzyme action and correctly describing the three main enzymes from the pancreas. Weaker candidates could not string the correct sequence together and scored very few marks. Better candidates wrote some sort of plan before starting, using the space below the instructions for Section B. This should be encouraged.
