Biology Nervous Coordination NUMS 2024
PMDC Verified Question 16 of 86
Which immediate change is brought about in the postsynaptic membrane on binding with excitatory neurotransmitter?
A
Calcium gates open
B
Sodium Potassium pump ceases to work
C
Sodium gets gates close
D
Sodium gates open
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Sodium gates open
Concept:

Excitatory neurotransmitters must encourage the postsynaptic cell to fire, which requires making the cell interior more positive.

Solution:

  • When an excitatory neurotransmitter (like glutamate or acetylcholine) binds to postsynaptic receptors, it triggers ligand-gated sodium gates to open. The resulting influx of positive \(\text{Na}^+\) ions initiates an Excitatory Postsynaptic Potential (EPSP), driving the cell toward threshold.


Why other options are incorrect:

  • Sodium gates close: This would prevent excitation entirely.


  • Calcium gates open: This happens in the presynaptic terminal to release the neurotransmitter, not primarily in the postsynaptic membrane to generate the impulse.


  • Pump ceases to work: The pump runs continuously in the background and is not immediately halted by synaptic binding.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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