The major reason why glucose is broken down in living organism is to obtain energy. The complete break down of glucose normally occur via four different stages, which are glycolysis, oxidation of pyruvate, TCA cycle and electron transport chain. For each molecule of glucose that is metabolized, 38 molecules of ATP are always obtained. ATP is the only form of energy that is usable by cells to carry out life sustaining activities of the cells.
During metabolism, the complete breakdown of one molecule of glucose results in a maximum yield of 38 molecules of ATP. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.
In break down of one molecule of glucose, the number of energy molecules gained at different level are as follows-
a) Glycolysis - 2 ATP are gained
b) Citric acid cycle- 2 ATP are gained
c) Electron transport chain- 34 ATP are gained (inclusive of conversion of NADH and FADH2 in terms of ATP , where on NADH is equal to 2 ATP molecule and one FADH2 is equal to one ATP molecule.)
Thus, total number of ATP gained from one cycle of break down of glucose
It can be anywhere been 32-38 molecules
ATP is the universal energy molecule of all cells and is produced in large quantities from the breakdown of glucose.
a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.