oh we have just done this in biology recently... photolysis occurs where it splits apart water molecules to make electrons and hydrogen ions (the H+ is used to reduce NaDP later on) and also O₂ is made as a by product
basically this is the equation 2H₂O⇒4e⁻ + 4H⁺ where the electrons replace the lost ones in chlorophyll
hope this helped :)
