Asystem is said to be in when no net change in the amounts of reactants and products occurs.

A system is said to be in Equilbrium when no net change in the amounts of reactants and products occurs. This is referred to as the chemical equilbrium; a state of balance in which the rates of the forward and reverses reactions are equal; no net change in the amounts of reactants and products occurs in the chemical system. However when a stress is applied to a system at equilibrium, the system changes in a way that relieves the stress according to the Le Chatelier's principle. 

Mitochondria is the cell organelle that produced the energy that is needed in the body system in form of atp, that is why it is called the power house of the cell. energy is needed by the living organisms to carry out the activities which sustain life.  if the mitochondria is destroyed atp will not be produced. if the mitochondria is destroyed, energy production will stop and the affected living organism will not have the energy to carry out the necessary life processes; this will lead to the death of the organism.