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

Which change shifts the oxyhaemoglobin dissociation curve to the right and facilitates tissue oxygen unloading?

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

The answer and the reasoning

D. Increased carbon dioxide

Increased carbon dioxide and hydrogen ion concentration reduce haemoglobin oxygen affinity, shifting the curve right and promoting oxygen release to metabolically active tissues through the Bohr effect.

Option by option

  • A. Decreased hydrogen ion concentration

    Lower hydrogen ion concentration means alkalosis, which shifts left.

  • B. Reduced 2,3-BPG

    Reduced 2,3-BPG also shifts the curve left.

  • C. Decreased temperature

    Lower temperature shifts the curve left and increases oxygen affinity.

  • D. Increased carbon dioxide (correct)

    Correct: increased carbon dioxide shifts the curve right.

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, Increased carbon dioxide. Increased carbon dioxide and hydrogen ion concentration reduce haemoglobin oxygen affinity, shifting the curve right and promoting oxygen release to metabolically active tissues through the Bohr effect.

Why is "Decreased hydrogen ion concentration" not the answer?

Lower hydrogen ion concentration means alkalosis, which shifts left.

Why is "Reduced 2,3-BPG" not the answer?

Reduced 2,3-BPG also shifts the curve left.

Why is "Decreased temperature" not the answer?

Lower temperature shifts the curve left and increases oxygen affinity.

What concept does this question test?

It tests Respiratory physiology in Physiology. The correct option holds because: Correct: increased carbon dioxide shifts the curve right.

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.