Photosynthesis is the basic reaction of green plants and many species of bacteria. The word photosynthesis means synthesis in presence of light (photo means light). So two most important requirements for photosynthesis to occur is the green color (cholorophyll) and sunlight. The basic chemical reaction for photosynthesis can be written as below:
6CO2 + 6H2O = ...
A brief but complete description of photosynthesis is given in this posting.The solution comprises of chemical reaction,photosystems,energy requirements and the waste product of photosystem.