Q.Most of the photosynthesis on Earth takes place by:

Photosynthesis is the physico-chemical process by which chlorophyll-bearing autotrophs (green plants, algae and cyanobacteria) trap light energy and use it to convert simple inorganic raw materials -- carbon dioxide and water -- into energy-rich organic food, releasing oxygen as a by-product. It is the defining process of autotrophic nutrition, since it lets these organisms manufacture their own organic food rather than consuming ready-made organic molecules from other organisms, as heterotrophs must. The overall reaction is conventionally summarised as $6CO_2 + 12H_2O \xrightarrow{\text{light, chlorophyll}} C_6H_{12}O_6 + 6O_2 + 6H_2O$, though it actually proceeds through many separate enzyme-catalysed steps. Photosynthesis is the ultimate source of food energy for almost every food chain on Earth and, separately, is the source of virtually al …