DP Chemistry (last assessment 2024)

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Question 19M.3.sl.TZ1.b

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.sl.TZ1.b
Level sl Paper 3 Time zone TZ1
Command term Outline Question number b Adapted from N/A
b.
[Maximum mark: 2]
19M.3.sl.TZ1.b

Mild heartburn is treated with antacids such as calcium carbonate.

Acid secretion can be regulated by other types of drugs such as omeprazole and ranitidine. Outline how each of these drugs acts to reduce excess stomach acid. 

 

Omeprazole:

Ranitidine:

[2]

Markscheme

Omeprazole:
inhibits enzyme/«gastric» proton pump «which secretes H+ ions into gastric juice»
OR
inhibits the H+/K+-ATPase system  [✔]

Ranitidine:
inhibits/blocks H2/histamine receptors «in cells of stomach lining»
OR
prevents histamine binding to H2/histamine receptors «and triggering acid secretion»  [✔]

Note: Accept “H2-receptor antagonist” for M2.

Examiners report

Many students correctly remembered the modes of action of Omeprazole and Ranitidine, though needless to say a few confused these and weaker students thought they acted like conventional antacids.

Syllabus sections