Haemoglobin: practice question

A Biochemistry 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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Biochemistry · Haemoglobin

Sample item

Which physiological change shifts the oxyhaemoglobin dissociation curve to the right?

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

The answer and the reasoning

A. Increased carbon dioxide concentration

Higher carbon dioxide, increased hydrogen ion concentration, higher temperature, and increased 2,3-BPG promote oxygen unloading by shifting the oxyhaemoglobin dissociation curve to the right.

Option by option

  • A. Increased carbon dioxide concentration (correct)

    Correct: increased CO2 lowers haemoglobin oxygen affinity and shifts the curve right.

  • B. Decreased temperature

    Lower temperature shifts the curve left and increases oxygen affinity.

  • C. Decreased 2,3-BPG

    Lower 2,3-BPG shifts the curve left.

  • D. Fetal haemoglobin predominance

    Fetal haemoglobin has higher oxygen affinity and shifts left.

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 Biochemistry question

What is the answer to this Biochemistry question?

The best answer is A, Increased carbon dioxide concentration. Higher carbon dioxide, increased hydrogen ion concentration, higher temperature, and increased 2,3-BPG promote oxygen unloading by shifting the oxyhaemoglobin dissociation curve to the right.

Why is "Decreased temperature" not the answer?

Lower temperature shifts the curve left and increases oxygen affinity.

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

Lower 2,3-BPG shifts the curve left.

Why is "Fetal haemoglobin predominance" not the answer?

Fetal haemoglobin has higher oxygen affinity and shifts left.

What concept does this question test?

It tests Haemoglobin in Biochemistry. The correct option holds because: Correct: increased CO2 lowers haemoglobin oxygen affinity and 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 Haemoglobin?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.