What is the primary role of NADH in aerobic respiration?

NADH plays a crucial role in aerobic respiration primarily by transporting electrons to the electron transport chain. During glycolysis and the citric acid cycle, glucose is broken down, and high-energy electrons are extracted. NADH serves as a carrier for these electrons, effectively storing the energy that was originally present in glucose.

As NADH is generated, it takes up electrons and is reduced to form NADH from NAD+. Once it reaches the electron transport chain, NADH donates these electrons, initiating a series of redox reactions that ultimately lead to the production of ATP via oxidative phosphorylation. This process relies on the energy released as electrons move through the chain, which is used to pump protons across the mitochondrial membrane, creating a proton gradient. This gradient then drives ATP synthase to produce ATP.

The other options do not accurately describe the role of NADH. While it does not act as a final electron acceptor (that role is fulfilled by oxygen), it also does not directly convert glucose into pyruvic acid or produce ATP directly. Instead, its primary function is to facilitate the transfer of electrons to the electron transport chain, making it an essential component of aerobic respiration.