| Date | November 2020 | Marks available | 6 | Reference code | 20N.3.HL.TZ0.9 |
| Level | Higher level | Paper | Paper 3 | Time zone | TZ0 / no time zone |
| Command term | Explain | Question number | 9 | Adapted from | N/A |
Question
Explain how psychoactive drugs affect the nervous system.
Markscheme
a. psychoactive drugs act upon the central nervous system/alter brain function;
b. psychoactive drugs are addictive;
Stimulants:
c. increase postsynaptic transmission;
d. mimic the stimulation provided by the sympathetic nervous system
OR
mimic action of natural stimulating neurotransmitters e.g. acetylcholine;
e. example: e.g. nicotine/cocaine/amphetamine;
Sedatives:
f. decrease postsynaptic transmission;
g. mimic inhibition (of the parasympathetic nervous system)
OR
mimic action of natural inhibiting neurotransmitters e.g. dopamine;
h. example: e.g. benzodiazepines/alcohol/tetrahydrocannabinol (THC);
Examiners report
Most candidates displayed a considerable knowledge about psychoactive drugs, but only the strongest candidates could provide focused answers and sufficient detailed mechanisms for both stimulants and sedatives on synapses.
