Acid-base biochemistry: 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 · Acid-base biochemistry

Sample item

Which buffer system is most important in extracellular blood plasma?

AHaemoglobin-free albumin onlyBPhosphate buffer onlyCLactate-pyruvate bufferDBicarbonate-carbonic acid buffer

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

The answer and the reasoning

D. Bicarbonate-carbonic acid buffer

The bicarbonate-carbonic acid system is the major extracellular buffer and is regulated by lungs through carbon dioxide and kidneys through bicarbonate handling.

Option by option

A. Haemoglobin-free albumin only
Albumin buffers but is not the main named system.
B. Phosphate buffer only
Phosphate is more important in cells and urine.
C. Lactate-pyruvate buffer
Lactate-pyruvate is not the chief blood buffer.
D. Bicarbonate-carbonic acid buffer (correct)
Correct: bicarbonate is the principal plasma buffer.

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, Bicarbonate-carbonic acid buffer. The bicarbonate-carbonic acid system is the major extracellular buffer and is regulated by lungs through carbon dioxide and kidneys through bicarbonate handling.

Why is "Haemoglobin-free albumin only" not the answer?

Albumin buffers but is not the main named system.

Why is "Phosphate buffer only" not the answer?

Phosphate is more important in cells and urine.

Why is "Lactate-pyruvate buffer" not the answer?

Lactate-pyruvate is not the chief blood buffer.

What concept does this question test?

It tests Acid-base biochemistry in Biochemistry. The correct option holds because: Correct: bicarbonate is the principal plasma buffer.

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 Acid-base biochemistry?

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.