Answer: Glucose is the molecule broken down.
Explanation: Cellular respirating is the process of combining food molecules and oxygen and using the chemical energy from these molecules to power all the activities that sustain life.
Cellular respiration releases energy stored in the chemical bonds of food molecules in three steps: Glycolysis, the krebs cycle, and the electron transport chain.
At each step GLUCOSE molecules interact with NAD+ and FAD+, and other compounds making different - sized carbon compounds and releasing energy.