<span>Cells need a source of energy, they get this energy by breaking down food molecules to release, the stored chemical energy.This process is called 'cellular respiration'. The process is happens in all the cells in our body. Oxygen is used to oxidize food, main oxidized food is sugar(glucose).</span><span>Jan 14, 2009</span>
Answer:
Variables are parameters that are monitored and controlled or affected by the feedback system
Explanation: