Photosynthesis is the basis of all life. Thus it is the most important biological process on earth. All green plants and some bacteria conduct photosynthesis for the build-up of biomass, which then is available to other organisms as food. In photosynthesis inorganic carbon dioxide is transformed into organic biomass.
Organisms that conduct photosynthesis meet their energy requirements through absorption and conversion of the light energy of the sun. Other life forms, such as all animals and human beings, must consume food to meet their energy and carbon requirements.
Photosynthesis enables plant and algae growth without "fuel consumption". In this process nutrients are constituted and oxygen is input in the water.