True or false: The two primary functions of the electron-transport chain (including oxidative phosphorylation) are to produce water and to convert ATP to ADP. Explain.

• A. False, one of the main functions is the oxidation of NADH and FADH₂, not the production of water, and ADP is converted to ATP, not the other way around.
• B. False, although ATP is converted to ADP to produce energy, the other main function is the oxidation of NADH and FADH₂, not the production of water.
• C. False, although the production of water is one of the main functions, ADP is converted to ATP, not the other way around.
• D. True, because the production of water is an important energy modulator and ATP is converted to ADP to produce energy.

Answer: (A)