Abstract Organisms obtain energy from outside in the form of free energy in order to drive life process and the whole process follows the laws of thermodynamics. The changes of free energy in chemical reactions can be added and chemical reactions in organisms can be coupled, which make thermodynamically unfavorable reactions in organisms can be promoted by thermodynamically favorable reactions. Adenosine triphosphate (ATP), as one of high-energy biological molecules, is direct energy source of life activities. It is these high-energy biological molecules that drive the chemical processes in living organisms. They transfer external energy to the energy of organisms to generate and maintain highly ordered structure in organisms.
