DP Chemistry (first assessment 2025)
Question 23M.2.SL.TZ2.18b
| Date | May 2023 | Marks available | [Maximum mark: 2] | Reference code | 23M.2.SL.TZ2.18b |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 2]
23M.2.SL.TZ2.18b
(b)
Explain how ranitidine (Zantac®) can also relieve excess stomach acid.
[2]
Markscheme
blocks/binds to H2/histamine receptors «in cells of stomach lining»
OR
prevents histamine binding to H2/histamine receptors «and triggering acid secretion» ✓
prevents «parietal cells from» releasing/producing acid ✓
Do not accept “antihistamine” by itself.
Accept “H2-receptor antagonist/H2RA”
OR
“blocks/inhibits action of histamine” for M1.
Do not accept “blocks receptors” alone for M1.
Do not accept “proton pump/ATPase inhibitor”.
