Oxygen gas is produced during photosynthesis by photolysis of water in the chloroplasts of algae and green plants and in the thylakoid of cyanobacteria. The chlorophyll of photosystem II absorbs light energy which leads to the excitation and knocking out of an electron within the photosystem.
The energy released as a result of returning the electrons to the ground state in an acceptor molecule is used in splitting water molecules into hydrogen and oxygen. The electron released from the splitting of water replaces the one knocked out from the photosystem II while oxygen atoms from two water molecules combine to form diatomic oxygen which is later released as oxygen gas.
The whole process of photolysis of water and the release of oxygen gas happens during the light-dependent reaction of photosynthesis.
The cerebrum which is located below the cerebral cortex serves as the main thought and control center of the brain. It is the seat of higher-level thought like emotions and decision making (as opposed to lower-level thought like balance, movement, and reflexes). It is known as the higher brain center
