Answer:
This simply refers to photolysis of water.
Step-by-step explanation
Generally,two steps are involved in photosynthesis.
The light dependent stage or light reaction,(which is the first part of photosynthesis,
The light independent stage (which is the second part.)
The light independent reactions involved the trapping of sunlight by the photo systems, in the leaves,and the splitting of the water molecules by sunlight.
H20 + Sunlight → 1/2H+ +2 e- +1/2 O2.
The movement of electron can be cyclic or non cyclic photophosphorylation, In Cyclic, photo system 1 absorbs the electrons and pass these to the primary pigments in the leaves. This excited the electron in chlorophyll molecule to higher energy levels , The electron emitted from the leaves is by a process called by photoactivation The emitted electron do not return to the photosystems,rather they are pick up by the primary electron acceptors and returned to the chlorophyll molecules by electron carriers,NADP.
During this process Energy is released for ATPase synthase of ATP for phosphorylation of ADP with phosphate,
In Non-cyclic photophorylation,photosystem I and II absorbs the electrons as Z-scheme movement of electrons.,Photoactivation of chlorophyll takes place as in the Cyclic.The primary electron acceptors takes the excited electrons to move along the chain of electron carriers.This makes the photosystems positively charged.
Hence to regain stability the primary pigment of photo system 1 takes electrons from photosystem II.To replace its lost electrons, P II takes electrons from the photolysis of water.ATP is generated as the carriers molecules transport electrons from the energy produced.
The hydrogen ions is used for the production of electrochemical gradients,which supplies the energy used by the ATPase synthase for the ATPs production.The process is called chemiosmosis. It involved the transports of H atoms by NADPH into the stroma,and the splitting of these into protons and electrons,The electrons form ETC,which forms the PMF.The latter pumped protons into the thylakoid membrane,and as this returns it generate the electrochemical gradient.
The ATP is used in the Calvin Cycle for CHO,proteins productions,