DP Biology (first assessment 2025)

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Question 23M.2.SL.TZ2.9

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Date May 2023 Marks available [Maximum mark: 6] Reference code 23M.2.SL.TZ2.9
Level SL Paper 2 Time zone TZ2
Command term Explain Question number 9 Adapted from N/A
9.
[Maximum mark: 6]
23M.2.SL.TZ2.9

Explain how communication between neurons during synaptic transmission is achieved through neurotransmitters.

[6]

Markscheme
  1. neurotransmitters are (chemicals) released by exocytosis/vesicles (in the pre-synaptic neuron) after the arrival of a nerve impulse;
  2. neurotransmitters leave the presynaptic neuron;
  3. (neurotransmitters) attach to receptors in the postsynaptic neuron;
  4. neurotransmitters (in the synaptic cleft) are broken down/reabsorbed;
  5. fast-acting neurotransmitters attach to protein-ion channels (in postsynaptic membrane);
  6. slow-acting neurotransmitters activate second messengers (in postsynaptic membrane);
  7. slow-acting neurotransmitters affect more than one neuron;
  8. some neurotransmitters excite nerve impulses (in postsynaptic neuron) while others inhibit them;
  9. excitatory neurotransmitter causes generation of action potential;
  10. inhibitory neurotransmitter prevents threshold being reached (preventing action potential);
  11. summation of all excitatory / inhibitory neurotransmitters received in postsynaptic neuron;

Mp e and f: accept correct named example of fast-acting or slow-acting neurotransmitters.

Mp i and j: Accept correct named examples of excitatory/inhibitory neurotransmitters.

Syllabus sections