Plants require carbon dioxide, light energy and water to complete photosynthesis. Photosynthesis results in the production of oxygen, water and glucose. Plants use glucose to store energy.
Photosynthesis occurs in a special organelle within plant cells called the chloroplast. Membranes enclose chloroplasts, which also contain thylakoid sacs, the green pigment chlorophyll and a dense fluid. The thylakoid sacs are the location of the light half of the photosynthesis reactions. During the light reactions, chlorophyll absorbs light to create to energetic molecules, ATP and NADPH. Also during the light reactions, water molecules split to form oxygen.
The stroma of the chloroplast is the site of the dark half of photosynthesis. The dark reactions involve carbon dioxide and do not require the immediate presence of light to proceed. At the outset of the dark reactions, carbon dioxide combines with a five-carbon sugar, RuBP, to create a sugar that is six carbons long. This six-carbon sugar splits into a pair of three-carbon sugars using the ATP and NADPH from the light reactions. Finally, some of the three-carbon sugars combine to become glucose, while the rest reform RuBP to continue the cycle. Photosynthesis produces oxygen that escapes the plant via stomata, which are openings in the leaves that the plant opens and closes to regulate levels of gas and water.