Photosynthesis

Photosynthesis is an important life process that provides more than 99% of the energy used by living things on Earth. Photosynthesis is composed of two main processes: the light reactions and the Calvin cycle. In the light reactions, pigment molecules, which give leaves their green color, drive ATP and NADPH production when excited by photons. The Calvin cycle takes the products of the light reactions and uses them to form O2 and sugar.