English: Organisms are not at equilibrium. They require a continuous influx of free energy to maintain order. Organisms maintain their non-equilibrium status by coupling the exergonic reactions of nutrient oxidation to the endergonic processes required to maintain the living state (such as the performance of mechanical work, the active transport of molecules against concentration gradients, and the biosynthesis of complex molecules). ATP and NADH serve as energy carriers that link the breakdown of food and biosynthesis of cellular compounds.