Hi! I represent the Dark Cycle of photosynthesis. During this, NADPH and ATP, which are produced in the light cycle, are used to make sugars.
And I represent the Light Reaction of photosynthesis! I convert solar energy in to chemical energy in the form of ATP and NADPH to assist in the making of sugar.
Dark reactions, A.K.A. the Calvin Cycle, do NOT require the energy found in sunlight to complete their reactions. During the Calvin Cycle, the inorganic CO2 is be transferred into carbohydrate so that the plant can grow and regenerate. This takes place in the stroma of the chloroplast. ATP and NADPH then combine with CO2 and water to make the final product of glucose. The ADP and NADPH+ are recycled to the light cycle to start the cycle over again. The main purpose of the Dark Cycle is making simple sugars out of CO2 and water. This is called carbon fixation.
The first part of photosynthesis, the light cycle, takes place inside the thylakoid of the chloroplast. It needs to absorb energy found in photons in the sunlight though chlorophyll to do its part. Therefore these reactions are "light-dependent."
During the light-dependent reaction, photons from sunlight are absorbed and processed through the membranes of the thylakoids. The photons excite electrons in the chlorophyll. This makes these electrons move through an electron transport chain, causing NADP- to combine with H+, resulting in NADPH. Simultaneously, ADP has been recycled from the Calvin Cycle and another phosphate train bonds, forming ATP. This then fuels the Calvin Cycle.
It is believed that all the oxygen exported by photosynthesis as a waste product is the consequence of hydrolsis, or the splitting of water. During the light-reaction, when water molecules are broken down they make 2 H+ ions and half an oxygen molecule. Full oxygen molecules are created when this happens again.