- A Coenzyme A, NAD+, and thiamine pyrophosphate acting together
- B Water alone, since the reaction is a straightforward hydrolysis
- C ATP alone, since the reaction is a simple phosphorylation step
- D Oxygen alone, since this is where O2 is first consumed in respiration
Correct answer: A. Coenzyme A, NAD+, and thiamine pyrophosphate acting together
Explanation: The pyruvate dehydrogenase complex uses multiple cofactors, including thiamine pyrophosphate, coenzyme A, and NAD+, to convert pyruvate into acetyl CoA, releasing CO2 in the process.
Concept context
Glycolysis, the Krebs cycle, the electron transport chain, fermentation, and the respiratory quotient. The cellular energy-release counterpart to photosynthesis.