Cellular Respiration Practice Test

During the electron transport chain, the final stage of cellular respiration, electrons are transferred through a series of protein complexes. This process occurs in the inner mitochondrial membrane and involves the reduction and oxidation of various electron carriers, including NADH and FADH2. As the electrons move along the chain, they lose energy, which is used to pump protons across the mitochondrial membrane, creating a proton gradient.

The final electron acceptor in this chain is molecular oxygen (O2). When the electrons combine with oxygen and the protons that have been pumped across the membrane, water (H2O) is produced as a byproduct. This reaction is crucial because it allows the electron transport chain to continue functioning by ensuring a flow of electrons. Thus, the production of water is a fundamental aspect of aerobic respiration, highlighting its importance in the energy-harvesting process of cells.