NAD\(^+\), NADP\(^+\), and which of the following are cofactors that participate in the reactions of cellular respiration?

• A. Glucose
• B. Pyruvate
• C. ATP
• D. FAD

Answer: (D)

Verified step by step guidance

1. Understand the role of cofactors in cellular respiration: Cofactors are non-protein molecules that assist enzymes in catalyzing reactions. In cellular respiration, cofactors like NAD⁺, NADP⁺, and FAD are involved in redox reactions, helping to transfer electrons.
2. Review the function of FAD: FAD (flavin adenine dinucleotide) is a cofactor that participates in the citric acid cycle (Krebs cycle) and the electron transport chain. It accepts electrons and hydrogen ions to form FADH₂, which is later used to generate ATP.
3. Eliminate incorrect options: Glucose is a substrate, not a cofactor. Pyruvate is an intermediate product of glycolysis and also not a cofactor. ATP is the energy currency of the cell, not a cofactor.
4. Confirm the correct answer: FAD is indeed a cofactor that participates in cellular respiration, specifically in the citric acid cycle and the electron transport chain.
5. Summarize the reasoning: The correct answer is FAD because it functions as a cofactor in redox reactions during cellular respiration, unlike glucose, pyruvate, or ATP, which have different roles in the process.