By definition, Cellular respiration is a biochemical process of breakdown of glucose with the help of oxygen into carbon-dioxide,water and energy.
The actual process is not simple as definition .Other compounds like fats,amino acids are also involved along with glucose.The fatty acids are broken down by beta oxidation to release acetyl-CoA, which then is fed into the citric acid cycle.Amino acids are oxidized to urea and carbon dioxide as a source of energy.Both end products are required for or in the energy production in the form of ATP.