Photosynthesis and respiration can be thought of as opposite processes.

Respiration Equation-
C6 H12 6 O2 + 6 O2 ----------)
6 CO2 + 6 H2O + energy

Cellular respiration occurs in the mitochondria of an organism's cells.

During respiration, cells break down simple food molecules such as glucose and release the energy they contain.

Respiration