DP Chemistry (last assessment 2024)
Question 23M.3.SL.TZ2.17
| Date | May 2023 | Marks available | [Maximum mark: 3] | Reference code | 23M.3.SL.TZ2.17 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain, Outline | Question number | 17 | Adapted from | N/A |
17.
[Maximum mark: 3]
23M.3.SL.TZ2.17
Opioids are a class of compounds that includes morphine and codeine.
(a)
Explain how strong analgesics like morphine work.
[2]
Markscheme
«temporarily» binding to receptors in the nervous system/spinal cord/brain ✓
preventing transmission of pain impulses ✓
Accept “bonding” for “binding” in M1.
Accept “without depressing the central nervous system” for M2.
(b)
Outline why codeine is a weaker analgesic than morphine.
[1]
Markscheme
codeine binds less to opioid receptors «than morphine»
OR
codeine must be metabolized «to morphine by enzymes» ✓
Accept “bonding” for “binding” in M1.
Accept correct name of inhibitor “fluoxetine” OR “citalopram”.
