The electron acceptor is molecular oxygen. Class I oxidases are cytochrome oxidases and use oxygen as the terminal electron acceptor. Fermentation reacts NADH with an endogenous, organic electron acceptor. They use sulfate as the terminal electron acceptor of their electron transport chain. Aerobic biodegradation dominates, i.e. the primary electron acceptor is O. CuPc usually plays the role of the electron donor in donor/acceptor based solar cells. The terminal electron acceptor in methanogenesis is not oxygen, but carbon. This method involves two fluorophores&colon; a donor and an acceptor. Oxygen is the final electron acceptor in the degradation of both purines. They use the nitrate as an electron acceptor in the place of oxygen during respiration. Hydrogen acceptor on inosinate oxidation is NAD+. Chlorophyll "a" accepts electrons from P700 before passing them along to another early electron acceptor. Arnon studied the Hill reaction using a natural electron acceptor, NADP. C has high electron affinity, making it a good acceptor. Phylloquinone A is the next early electron acceptor in PSI.