Figure 6: The red square shown in (2) is the two electron leak pathways mediated by cytochrome c proved in our lab. It suggests the appearance of the detoxify event in the early stage of oxygen. The highly evolved respiratory chain, shown in (3), has a big change in the direction of the electron transfer in complex II. The experimental evidence is performed in the purified complex II [10]. The normal electron transfer of complex II is from succinate to cytochrome b560; once the oxygen in the reaction medium is replaced by argon, the electron transfer changed from cytochrome b560 to succinate.