What is the role of enzymes in cellular respiration?

• A. Enzymes catalyze reactions that transfer electrons during the process
• B. Enzymes provide energy directly
• C. Enzymes store genetic information
• D. Enzymes transport ATP across membranes

Answer: (A)

Enzymes accelerate the redox steps that move electrons during cellular respiration. They catalyze each oxidation-reduction reaction across glycolysis, pyruvate oxidation, the citric acid cycle, and the electron transport chain, enabling electrons to be transferred to carriers like NAD+ and FAD to form NADH and FADH2. These carriers then deliver electrons to the electron transport chain, and the energy from these transfers powers proton pumping to create a proton gradient. ATP synthase uses that gradient to make ATP. Enzymes don’t provide energy themselves, nor do they store genetic information or shuttle ATP across membranes; their role is to speed and regulate the chemical reactions that transfer electrons throughout respiration.