Neurophysiology: neuromuscular junction: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Neurophysiology: neuromuscular junction

Sample item

Botulinum toxin causes flaccid paralysis by preventing presynaptic release of which neurotransmitter?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Acetylcholine

Botulinum toxin cleaves SNARE proteins required for acetylcholine vesicle fusion at cholinergic nerve terminals. Failure of neuromuscular transmission produces descending flaccid weakness.

Option by option

  • A. GABA

    GABA is the main inhibitory CNS transmitter.

  • B. Dopamine

    Dopamine is important in basal ganglia pathways, not motor endplate transmission.

  • C. Glutamate

    Glutamate is the main CNS excitatory transmitter.

  • D. Acetylcholine (correct)

    Correct. Acetylcholine release at the motor endplate is blocked.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, Acetylcholine. Botulinum toxin cleaves SNARE proteins required for acetylcholine vesicle fusion at cholinergic nerve terminals.

Why is "GABA" not the answer?

GABA is the main inhibitory CNS transmitter.

Why is "Dopamine" not the answer?

Dopamine is important in basal ganglia pathways, not motor endplate transmission.

Why is "Glutamate" not the answer?

Glutamate is the main CNS excitatory transmitter.

What concept does this question test?

It tests Neurophysiology: neuromuscular junction in Physiology. Failure of neuromuscular transmission produces descending flaccid weakness.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Neurophysiology: neuromuscular junction?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.