Muscle physiology: 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 · Muscle physiology

Sample item

What directly binds calcium to initiate skeletal muscle contraction?

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

The answer and the reasoning

A. Troponin C

Calcium binds troponin C, moving tropomyosin away from actin binding sites and allowing myosin cross-bridge cycling to begin.

Option by option

  • A. Troponin C (correct)

    Correct: troponin C senses calcium in skeletal muscle.

  • B. Myosin heavy chain

    Myosin generates force after actin sites are exposed.

  • C. Tropomyosin

    Tropomyosin blocks actin sites until shifted.

  • D. Titin

    Titin provides elastic structural support in sarcomeres.

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 A, Troponin C. Calcium binds troponin C, moving tropomyosin away from actin binding sites and allowing myosin cross-bridge cycling to begin.

Why is "Myosin heavy chain" not the answer?

Myosin generates force after actin sites are exposed.

Why is "Tropomyosin" not the answer?

Tropomyosin blocks actin sites until shifted.

Why is "Titin" not the answer?

Titin provides elastic structural support in sarcomeres.

What concept does this question test?

It tests Muscle physiology in Physiology. The correct option holds because: Correct: troponin C senses calcium in skeletal muscle.

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 Muscle physiology?

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.