Photosynthesis is actually a complex series of chemical reactions.
There are many such series in living things known as biochemical pathways . While all these chemical systems are important, none are more important than photosynthesis and respiration . Even though glucose is a source of energy for living things, Adenosine triphosphate , ATP , is the energy molecule used by most organisms. This energy is available for cells to carry on their life processes. Chemically, cellular respiration is the exact opposite of photosynthesis.