Question 20N.3.HL.TZ0.c.ii
| Date | November 2020 | Marks available | [Maximum mark: 3] | Reference code | 20N.3.HL.TZ0.c.ii |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain | Question number | c.ii | Adapted from | N/A |
The human stomach kills pathogenic bacteria while allowing some benefi cial bacteria to survive. The diagram shows how mucus lining the stomach helps in this process.
[Source: Kavanaugh, D., O’Callaghan, J., Kilcoyne, M., Kane, M., Joshi, L. and Hickey, R.M., 2015. The intestinal glycome and
its modulation by diet and nutrition. Nutrition Reviews, 73(6), pp.359–375 by permission of Oxford University Press on behalf
of the International Life Sciences Institute. Translated and reprinted by permission of Oxford University Press on behalf of the
International Life Sciences Institute. Please visit: https://academic.oup.com/nutritionreviews/article/73/6/359/1845190.]
There are times when pathogenic bacteria infect the stomach, causing ulcers.
Explain how proton pump inhibitors (PPIs) reduce conditions that favour ulcer formation.
[3]
a. acidity is achieved by a proton pump/H+, K+-ATPase;
b. exchange of H+ from the cytoplasm for K+ ions in the lumen;
c. PPIs bind irreversibly to the (proton) pump;
d. lowering amount of acid produced/H+;
Strong candidates distinguished themselves in this question, although most could state that their action lowered the volume of hydrochloric acid produced.
