Respiration: 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 · Respiration

Sample item

Which of the following shifts the oxygen–haemoglobin dissociation curve to the right?

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

The answer and the reasoning

B. Increased 2,3-BPG

A right shift lowers haemoglobin's affinity for oxygen and helps unloading in tissues: raised 2,3-BPG, CO₂, H⁺ (the Bohr effect) and temperature. Left shifts come from the opposite changes, fetal haemoglobin and carbon monoxide.

Option by option

  • A. Alkalosis

    Alkalosis raises affinity and shifts the curve left.

  • B. Increased 2,3-BPG (correct)

    Correct. 2,3-BPG binds deoxyhaemoglobin and favours oxygen release, as in chronic hypoxia and high altitude.

  • C. Decreased temperature

    Cooling increases affinity and shifts the curve left.

  • D. Fetal haemoglobin

    HbF binds 2,3-BPG poorly so it holds oxygen more tightly (left shift), which helps the fetus extract oxygen from maternal blood.

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 B, Increased 2,3-BPG. A right shift lowers haemoglobin's affinity for oxygen and helps unloading in tissues: raised 2,3-BPG, CO₂, H⁺ (the Bohr effect) and temperature.

Why is "Alkalosis" not the answer?

Alkalosis raises affinity and shifts the curve left.

Why is "Decreased temperature" not the answer?

Cooling increases affinity and shifts the curve left.

Why is "Fetal haemoglobin" not the answer?

HbF binds 2,3-BPG poorly so it holds oxygen more tightly (left shift), which helps the fetus extract oxygen from maternal blood.

What concept does this question test?

It tests Respiration in Physiology. Left shifts come from the opposite changes, fetal haemoglobin and carbon monoxide.

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 Respiration?

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.