: Photosynthesis is completed in two phases-Photocbemical or light reactions or light dependent reactions and dark Reactions or Light independent reactions. In this phase, oxidation of water occurs and energy from sunlight is absorbed and converted to chemical energy which is stored in ATP and NADPH+H+ In dark reaction CO2 is reduced to form carbohydrates using the energy stored in the ATP and NADPH formed in the light independent reactions.