Bioenergetics in photosynthesis is the major biological processes occur inside the cells of plants, algae and certain bacteria converting light energy into chemical energy obtained from the sun light as major source for photosynthetic species. Light energy absorbed by reaction centers present in the chloroplasts. From a purely thermodynamic standpoint, life is an improbable event. Consider, for example, the complex structures of organisms, not only at the macroscopic level, but also at the microscopic and atomic levels. These ordered structures can be formed and maintained only by the expenditure of energy. Within the ecosystem that we call the earth, the organic nutrients necessary to sustain the life of heterotrophy such as us are provided directly and indirectly by photosynthesis. In both quantitative and qualitative terms photosynthesis is the most significant biological process on Earth. Approximately 2 x 1011 tons of carbon dioxide is converted to organic compounds each year. It is to photosynthesis in prehistoric times that we owe the reserves of fossil fuels. The oxygen that we breathe is a direct result of photosynthesis, now and in prehistory.