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NEET 2018 · BiologyPrevious Year Question

What is the role of NAD+ in cellular respiration?

Answer: (B) It functions as an electron carrier.. Answer: (B) It functions as an electron carrier.

  1. A.It is a nucleotide source for ATP synthesis.
  2. B.It functions as an electron carrier.✓
  3. C.It functions as an enzyme.
  4. D.It is the final electron acceptor for anaerobic respiration.

Correct Answer

(B) It functions as an electron carrier.

Solution & Explanation

Answer: (B) It functions as an electron carrier. Solution: NAD+ accepts hydrogen atoms/electrons (redox equivalents) during glycolysis and the TCA cycle to become NADH + H+, then delivers those electrons to the ETS, acting as a mobile electron (hydrogen) carrier. It is a coenzyme, not an enzyme (C); it is not consumed to build ATP's nucleotide backbone (A); and in respiration O2 is the final electron acceptor, while in fermentation pyruvate itself is reduced, not NAD+ (D). NCERT: Ch 12, p.156, line ~36: "Two redox-equivalents are removed (in the form of two hydrogen atoms) from PGAL and transferred to a molecule of NAD+".

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