Answer: The mechanisms of phosphorylation and oxidation are directly coupled. Normally ATP synthase complex enable synthesis of ATP by pumping protons from mitochondria matrix at complexes, I, III and IV total 2 ATP are produced per one complex thereby 2H+ are driven via proton motive force to produce 1 ATP. The mechanisms of phosphorylation and oxidation are not directly coupled but proton transport & phosphorylation are directly coupled. The P/O ratio for NADH in the oxidative phosphorylation is 2.5 ATP/NADH (recent research has revealed this information i.e. P/O ratios of 2.5 ATP/NADH). Succinate is going to generate “1.5 ATP/FADH2“ because oxidation of FADH2 is going to pump 6 H+ per FADH2 to generate ATP using F0-F1 complex (Fernandez –Moran complex) in the presence of ATP synthase. Therefore, the net energy is higher than the energy required to pump H+ ions through ATP synthase to generate ATP. Solution Answer: The mechanisms of phosphorylation and oxidation are directly coupled. Normally ATP synthase complex enable synthesis of ATP by pumping protons from mitochondria matrix at complexes, I, III and IV total 2 ATP are produced per one complex thereby 2H+ are driven via proton motive force to produce 1 ATP. The mechanisms of phosphorylation and oxidation are not directly coupled but proton transport & phosphorylation are directly coupled. The P/O ratio for NADH in the oxidative phosphorylation is 2.5 ATP/NADH (recent research has revealed this information i.e. P/O ratios of 2.5 ATP/NADH). Succinate is going to generate “1.5 ATP/FADH2“ because oxidation of FADH2 is going to pump 6 H+ per FADH2 to generate ATP using F0-F1 complex (Fernandez –Moran complex) in the presence of ATP synthase. Therefore, the net energy is higher than the energy required to pump H+ ions through ATP synthase to generate ATP..