(a) : The chemiosmotic coupling hypothesis of oxidative phosphorylation proposed by Mitchell, explains the process of ATP formation and states that it is linked to development of a proton gradient across a membrane. ATP synthase, required for ATP synthesis is located in F1 particles present in the inner mitochondrial membrane and becomes active only when there is high concentration of proton on F0 side as compared to F1 side. The flow of proton through F0 channel induces F1 particle to function as ATP synthase and the energy of proton gradient produces ATP by attaching a phosphate radical to ADP.