Photolysis of water: It is a light-mediated oxidation process associated with PSII characterized by the splitting of a water molecules into electrons, hydrogen ions and oxygen. The electrons released during photolysis are accepted by P680 of PSII, which has lost its electron due to excitation. The H+ ions released are used to reduce NADP toNADPH+H+ that enters the dark reaction of photosynthesis. The reaction is as follows:
2H2O→Mn+2,Ca+2,Cl−SunlinghtO2+4H++4e−