Thermodynamically stable molecules with strong chemical bonds absorb energy from the sun (or other energy sources). These simple molecules (N2, CO2, H2O, etc.) share out their excess free energy with other molecules and redistribute this energy between them. Usually these simple molecules are combined to form a more complex substance. This association leads to a spontaneous redistribution of the energy of strong chemical bonds. As a result of this relatively weak bonds are appeared inside the newly formed complex molecules. Such molecules have the low chemical stability compared with predecessor chemicals.
Thus the complex molecules with relatively weak chemical bonds are appeared. These molecules are united into supramolecular (intermolecular) structure spontaneous. This association prevents the breakdown of relatively weak chemical bonds of these complex molecules. Such process of stabilization structures of all hierarchies observed at all structural levels of living matter. This is the effect of action of the thermodynamic principle of substance stability which governs by the natural selection and eventually – evolution.
However, the accumulation of relatively weak chemical bonds in molecules and weak links between the structures inside of the higher hierarchies reduces the stability of the structures at all levels. This increases the rate of spontaneous decay of structures and at all hierarchical levels.
The decay of low-stabile chemicals significantly accelerated in the presence of oxygen, which appeared in the course of evolution in the earth’s atmosphere. As a result of the action of oxygen the different metabolites (intermediate oxygen-containing molecules) are formed.
Finally, the cycle ends: again are formed stable chemicals. These substances are able to absorb the energy from environment again. The cycle of metabolism, which is adapted by hierarchical thermodynamics to new organisms (that have emerged as a result of natural selection, and changing of environmental conditions) is repeated.
Note that the cycles of metabolism observed at all hierarchical levels: atomic, molecular, supramolecular, cellular, organism, population, environmental level and at all hierarchical sublevels. This exchange of substances is an essential characteristic of life.
Gladyshev Georgi P. Thermodynamics Theory of the Evolution of Living Beings.- Commack, New York: Nova Science Publishers, Inc.- 1997.- 142 P.
Gladyshev G.P. On the Principle of Substance Stability and Thermodynamic Feedback in Hierarchic Systems of Bioworld . Biol. Bulletin. 2002. Vol. 29, No. 1, pp. 1-4 http://creatacad.org/doc/news2-5.pdf
Gladyshev G.P. The Principle of Substance Stability is Applicable to all Levels of Organization of Living Matter // Int. J. Mol. Sci.- 2006.- 7.- P. 98-110.