: Synthesis and respiration are the two major biochemical processes in an organism. There is a close relationship between these two processes. In the process of photosynthesis, plants bind solar energy to food , and the body releases that energy for various biological functions through respiration. In the process of photosynthesis CO 2 is taken and O 2 is emitted , again in the process of respiration O 2 is taken and CO 2 is emitted. Thus the correct ratio of O 2 and CO 2 gases in the atmosphere is maintained through these two processes .