Glucose is broken down through cellular respiration, which involves a large number of chemical reactions. At the end of the cellular respiration process, a large number of ATP molecules are generated, yet not all of the possible energy that is contained in a molecule of glucose can be harnessed through these chemical reactions to generate ATP. In other words, during cellular respiration, not all of the energy that is contained in a molecule of glucose is converted into the energy stored in ATP. The remaining energy is

It is worthy to note that according to the law of thermodynamics, energy transfer cannot be hundred percent efficient. This law manifests in the breakdown of glucose by the body during cellular respiration. Aside from the energy used for the process of cellular respiration itself, the rest of the energy untapped are released by the cells as heat to warm the body (insulation) and helps maintain a normal optimal temperature of the body. Cellular respiration process produces energy which are stored as ATP, about 36-38 molecules of ATP is generated in cellular respiration by the cells. The remaining energy contained in the glucose molecules are converted to heat.