Botany - Photosynthesis in Higher Plants Question with Solution | TestHub

There are two stages of photosynthesis, the first one wherein the light reactions occur in the thylakoids and the second which occurs in the stroma, known as the Calvin cycle. Hydrogen which is used for the synthesis of organic compounds in this process comes from the photolysis of water. Two water molecules are oxidized by four charge-separation reactions by the photosystem II. This results in the formation of an oxygen molecule and four hydrogen ions.