Biology Enzymes UHS 2023
PMDC Verified Question 19 of 79
NAD is an important?
A
Enzyme
B
Vitamin
C
Coenzyme
D
Hormone
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Coenzyme
Concept:

In cellular respiration, enzymes require organic helper molecules to transfer electrons safely between metabolic pathways.

Solution:

  • NAD (Nicotinamide Adenine Dinucleotide) is an organic, non-protein molecule derived from Vitamin B3 (niacin).
  • It binds loosely and temporarily to redox enzymes (dehydrogenases) to accept and donate electrons (as \( \text{NADH} \)).
  • Because it is an organic, detachable helper molecule, it is officially classified as a Coenzyme.


Why other options are incorrect:

NAD is not a protein, so it cannot be an enzyme. It is derived from a vitamin, but it is not the vitamin itself. It does not act as a hormone (signaling molecule) in the endocrine system.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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