Photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms' activities (energy transformation This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon and auv0Eouc, dioxide and water hence the name photosynthesis, from the Greek phos ght n most cases, oxygen is also released as a waste product. Most plants, most synthesis, "putting together". I such organisms are called photoautotrophs and cyanobacteria perform photosynthesis algae and supplies all of the organic compounds and most of Photosynthesis maintains atmospheric oxygen l the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process al begins when energy from light is absorbed by proteins called reaction centres that contain green in plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cell while in bacteria they are embedded in the plasma membrane In these light-dependent reactions, som as water, producing oxygen gas. The energy is used to strip electrons from suitable substances, s hydrogen freed by water splitting is used in the creation of two further compounds: reduced nicotinamide phosphate and adenosine triphosphate (ATP), the "energy currency" of cells In plants, algae and cyanobacteria, sugars are produced by a subsequent sequence of light-independent reactions called the Calvin but some bacteria use different mechanisms, such as the reverse Krebs cycle. In the Calvin cycle, atmospheric dioxide is incorporated into already existing organic carbon carbon compounds, as ribulose bisphosphate (RuBP). using the ATP and NADPH produced by the light such then reduced and removed to form further dependent reactions, the resulting compounds are carbohydrates, such as glucose. The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or hydrogen sulfide, rather than water, as sources of electrons. cyanobacteria appeared later; the excess oxygen they produced contributed to the oxygen catastrophe, which rendered the evolution of complex life possible. Today, the average rate of energy capture by photosynthesis globally is approximately 130 terawatts, which is about three times the current power consumption of human civilization. Photosynthetic organisms also convert around 100-115 thousand million metric tonnes of carbon into biomass per year. Sun's energy CO, H Oxygen Sugars