ATP is produced during the light-dependent portion of photosynthesis, and this ATP fuels the light-independent portion of the process. Without ATP, photosynthesis cannot take place.
Photosynthesis is the process in which plants use sunlight, carbon dioxide and water to make food. During the process, a plant harvests energy and stores it in a chemical called ATP, which is made of a nucleotide bond attached to three phosphate groups. This storing of energy does not need light to take place, hence the process being light-independent; however, it uses all the components of the light reaction to occur. The process of using the energy stored in ATP during the light-independent cycles of photosynthesis is called the Calvin cycle.