Differences between cellular respiration and combustion?

Answer 1

Though cellular respiration shares the same overall chemical equation as the combustion of glucose in oxygen, there have to be key differences between the two processes or we'd all be burning inside our cells.

The main difference, then, is that for cellular respiration, the energy release from glucose is performed in a very controlled manner using enzymes to both lower the activation energy of the reaction steps so that they can happen at body temperature and to spread out the energy release into small steps over a relatively long period of time. For combustion, the initial activation energy is high (a high temperature needed to start the burning, as seen by the high temperature needed for sugars to burn while cooking), and the energy release is very rapid, with all the chemical energy stored in the bonds released near-instantaneously, providing very large amounts of energy in a short period of time.

Answer 2

Cellular respiration is a controlled process which occurs in living cells to break down glucose into energy, whereas combustion is a chemical process involving the rapid oxidation of a fuel in the presence of oxygen, often resulting in the release of heat and light. Additionally, cellular respiration produces ATP as a form of energy for the cell, while combustion primarily produces heat and light energy.