Photosynthesis begins when a plant's chlorophyll in the chloroplasts capture energy from the sun. Water is taken up from the soil, and carbon dioxide enters the leaves through the stomates. The light energy is used to convert water and carbon dioxide into glucose, and oxygen is given off.
The first part of photosynthesis is called the light dependent reaction. During this phase, light energy is captured and stored in a chemical called adenosine triphosphate, or ATP. The second phase, the light independent reaction, involves using the ATP to make glucose during the Calvin Cycle. When light gets to a plant, it does not use all of it. The plant absorbs mostly red and blue wavelengths. Although some of the glucose is used for respiration and some of it is converted into starch for storage, the stored starch can be used later for respiration and to make glucose.
Photosynthesis is a type of autotropic nutrition, meaning that the organism can make nutrients that it needs for energy and growth using materials from its environment. Photosynthesis allows certain organisms to make the energy from sunlight usable, because living things can eat glucose but not sunlight. Temperature, carbon dioxide levels and light intensity are factors that affect the rate of photosynthesis.