The main properties of living systems are:
1. The unity of the chemical composition. Although the composition of living systems includes the same chemical elements as in the objects of inanimate nature, the ratio of various elements in living and nonliving is not the same. In living organisms, 98% of the chemical composition is accounted for by six elements: oxygen (–62%), carbon (–20%), hydrogen (–10%), nitrogen (–3%), calcium (–2.5%), phosphorus (-1.0%). In addition, living systems contain a combination of complex polymers, mainly proteins, nucleic acids, enzymes, etc., which are not inherent to inanimate systems.
2. The openness of living systems. Living systems are open systems. Living systems use external sources of energy in the form of food, light, etc. Flows of substances and energy pass through them, due to which metabolism – metabolism – is carried out in the systems. The basis of metabolism is anabolism (assimilation), that is, the synthesis of substances, and catabolism (dissimilation), that is, the decomposition of complex substances into simple ones with the release of energy, which is used for biosynthesis.
3. Living systems – self-governing, self-regulating, self-organizing systems.
Self-regulation is the property of living systems to automatically establish and maintain at a certain level certain physiological (or other) indicators of the system. Self-organization is the ability of a living system to adapt to changing conditions by changing the structure of its control system. With self-regulation and self-organization, control factors act on the system not from outside, but arise in it itself in the process of processing information that a living system exchanges with the external environment. This means that living systems are self-governing systems.
4. Living systems – self-reproducing systems. Living systems exist for a finite time. Maintenance of life is associated with self-reproduction, due to which a living creature reproduces its own kind.
5. The variability of living systems. Variability is associated with the acquisition by the body of new traits and properties. This phenomenon is the opposite of heredity and plays a role in the selection process of organisms that are most adapted to specific conditions.
6. Ability to grow and develop. Growth – an increase in size and weight while maintaining common structural features; growth is accompanied by development, that is, the emergence of new traits and qualities. Development can be individual (ontogenesis), when all the properties of an organism are successively manifested, and historical, which is accompanied by the formation of new species and the progressive complication of the living system (phylogenesis).
7. Irritability is an integral feature of all living things. Irritability is associated with the transfer of information from the external environment to a living system and is manifested in the form of system reactions to external influences.