In order to determine the relationship of the two biological processes, it would be better to define them generally. Photosynthesis is a series of processes that converts light energy into chemical energy that can be used by the cell to maintain its metabolic functions. The overall chemical equation for the photosynthesis that occurs in plants can be written as:
`6 CO_2 + 6 H_2O + light en ergy -> C_6H_12O_6 + 6 O_2`
Conversely, the cellular respiration can simply be the conversion of biochemical energy into Adenosine Triphosphate (ATP). Respiration can have a general equation to have:
`C_6H_12O_6 + 6 O_2 -> 6 CO_2 + 6 H_2O + heat (en ergy)`
Obviously, the equation of respiration is the reversed of the photosynthesis. Plants produce oxygen that can be used by the respiration to produce ATP. Respiration produces Carbon dioxide that photosynthesis needs to perform its function.