Haemoglobin: 2,3-BPG in stored blood: 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: 2,3-BPG in stored blood

Sample item

A patient receives several units of red cells stored for 3 weeks in citrate-phosphate-dextrose. Immediately after transfusion the transfused cells deliver oxygen poorly. What is the biochemical reason?

ALoss of the haem iron from haemoglobinBRaised 2,3-bisphosphoglycerate stabilises the R state too stronglyCConversion of haemoglobin to its carbamino formDDepleted 2,3-bisphosphoglycerate shifts the dissociation curve to the left

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

The answer and the reasoning

D. Depleted 2,3-bisphosphoglycerate shifts the dissociation curve to the left

2,3-BPG binds the central cavity of deoxyhaemoglobin and stabilises the T state, lowering oxygen affinity. During storage red cell 2,3-BPG falls, so haemoglobin favours the R state and holds oxygen more tightly (left shift). The level recovers over roughly 24 to 48 hours after transfusion.

Option by option

A. Loss of the haem iron from haemoglobin
Haem iron stays bound in stored red cells, and the problem is allosteric, not structural.
B. Raised 2,3-bisphosphoglycerate stabilises the R state too strongly
2,3-BPG stabilises the T state, and in stored blood it is reduced, not raised.
C. Conversion of haemoglobin to its carbamino form
Carbamino formation involves CO2 and slightly lowers oxygen affinity; it is not the cause here.
D. Depleted 2,3-bisphosphoglycerate shifts the dissociation curve to the left (correct)
Correct. Less 2,3-BPG means higher oxygen affinity and reduced unloading in tissues.

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.

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Depleted 2,3-bisphosphoglycerate shifts the dissociation curve to the left. 2,3-BPG binds the central cavity of deoxyhaemoglobin and stabilises the T state, lowering oxygen affinity.

Why is "Loss of the haem iron from haemoglobin" not the answer?

Haem iron stays bound in stored red cells, and the problem is allosteric, not structural.

Why is "Raised 2,3-bisphosphoglycerate stabilises the R state too strongly" not the answer?

2,3-BPG stabilises the T state, and in stored blood it is reduced, not raised.

Why is "Conversion of haemoglobin to its carbamino form" not the answer?

Carbamino formation involves CO2 and slightly lowers oxygen affinity; it is not the cause here.

What concept does this question test?

It tests Haemoglobin: 2,3-BPG in stored blood in Biochemistry. During storage red cell 2,3-BPG falls, so haemoglobin favours the R state and holds oxygen more tightly (left shift). The level recovers over roughly 24 to 48 hours after transfusion.

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: 2,3-BPG in stored blood?

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.