Respiratory 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 · Respiratory physiology

Sample item

What does a ventilation-perfusion ratio describe in the lung?

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

The answer and the reasoning

A. Relationship between alveolar ventilation and pulmonary blood flow

The ventilation-perfusion ratio compares air reaching alveoli with blood reaching pulmonary capillaries; regional mismatch impairs gas exchange and can contribute to hypoxaemia in many lung disorders.

Option by option

  • A. Relationship between alveolar ventilation and pulmonary blood flow (correct)

    Correct: V/Q compares alveolar ventilation with pulmonary perfusion.

  • B. Amount of oxygen dissolved in plasma

    Dissolved oxygen is determined by partial pressure and solubility.

  • C. Ratio of inspiratory to expiratory time

    Inspiratory-expiratory timing is a different respiratory measurement.

  • D. Number of breaths per minute

    Breathing frequency alone is respiratory rate.

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, Relationship between alveolar ventilation and pulmonary blood flow. The ventilation-perfusion ratio compares air reaching alveoli with blood reaching pulmonary capillaries; regional mismatch impairs gas exchange and can contribute to hypoxaemia in many lung disorders.

Why is "Amount of oxygen dissolved in plasma" not the answer?

Dissolved oxygen is determined by partial pressure and solubility.

Why is "Ratio of inspiratory to expiratory time" not the answer?

Inspiratory-expiratory timing is a different respiratory measurement.

Why is "Number of breaths per minute" not the answer?

Breathing frequency alone is respiratory rate.

What concept does this question test?

It tests Respiratory physiology in Physiology. The correct option holds because: Correct: V/Q compares alveolar ventilation with pulmonary perfusion.

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 Respiratory 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.