Question 19M.3.HL.TZ2.d
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.3.HL.TZ2.d |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Outline | Question number | d | Adapted from | N/A |
Most stomach ulcers are caused by a bacterium that lives under the mucus lining of the stomach wall.
This organism causes the production of reactive compounds which result in oxidation. This makes the ulcer progress and, consequently, healing is more difficult. A study was carried out to compare the effect of the drug nizatidine (N) alone or combined with the antioxidants vitamin E and thioctic acid.
[Source: Effect of Helicobacter Pylori Eradication Therapy and some Antioxidants on Ulcer Healing Rates
in Patients with Helicobacter pylori-associated Duodenal Ulcer, Ahmed M Ali, 2013, http://www.rroij.com/
open-access/effect-of-helicobacter-pylori-eradication-therapy-and-some-antioxidants-on-ulcer-healingrates-
in-patients-with-helicobacter-pylor-.php?aid=34774, licensed under a
Creative Commons Attribution 4.0 International License]
Gastric juice production can be inhibited by the hormone secretin which is a polypeptide. Outline the mechanism by which a peptide hormone carries out its function.
[3]
a. bind to plasma membrane receptors of «target» cell ✔
b. results in activation/release/synthesis of a secondary messenger ✔
c. triggers a cascade of reactions ✔
d. leads to promotion/inhibition of enzymes
OR
causes activation of protein kinase «resulting in hormonal effect» ✔
Many candidates provided a correct, complete answer. Some nevertheless inverted the order of the production of a second messenger and the cascade of reactions, which occurs afterwards to cause the multiplying effect of the hormone. A noticeable number, especially in French, outlined the action of secretin in digestion instead of answering the question. A few confused peptide hormones with steroid hormones.
