Photosynthesis is the process made by autotrophs (plants and algae) by which they can take energy from the sun to form sugars such as glucose in order to use it as a source of energy, and also to store it as other molecules as starch for example. As this organisms are primary producers, the energy they take from the sun and convert into chemical energy (ATP) also is usable to all the organisms higher in the food chain. Moreover, during the process of photosynthesis they absorb CO2 and release O2.