What is produced as a result of the electron transport chain?

The electron transport chain is a crucial component of cellular respiration that occurs in the inner mitochondrial membrane. During this process, electrons derived from NADH and FADH2, which are generated in earlier stages of respiration (such as glycolysis and the Krebs cycle), are transferred through a series of protein complexes. As the electrons move along this chain, their energy is used to pump protons (H+) from the mitochondrial matrix into the intermembrane space, creating a proton gradient.

This proton gradient drives the synthesis of ATP as protons flow back into the matrix through ATP synthase, an enzyme that orchestrates the conversion of ADP and inorganic phosphate into ATP. Additionally, at the end of the electron transport chain, the electrons combine with oxygen (the final electron acceptor) and protons to form water. This step is essential in preventing the backup of electrons and maintaining the flow through the chain.

Thus, the primary products of the electron transport chain are ATP and water, making this option the correct answer.