Q.In the electron transport system of aerobic respiration, the final acceptor of electrons at the end of the chain is:

The electron transport system (ETS), embedded in the inner mitochondrial membrane (cristae), oxidises the NADH and FADH2 generated by glycolysis, the link reaction and the TCA cycle, using the energy released to generate the great majority of aerobic respiration's ATP through oxidative phosphorylation. NADH delivers electrons to Complex I; FADH2 delivers electrons to Complex II, bypassing Complex I. Electrons pass via ubiquinone to Complex III and via cytochrome c to Complex IV, where they finally combine with oxygen -- the terminal electron acceptor -- and protons to form water; this is the only step requiring oxygen. As electrons pass through Complexes I, III and IV, protons are actively pumped from the matrix into the intermembrane space, building a proton gradient (proton-motive force). Per the chemiosmotic …