Living systems have common features:
1.the unity of the chemical composition testifies to the unity and connection of living and inanimate matter.
Example: the composition of living organisms includes the same chemical elements as objects of inanimate nature, but in different quantitative ratios (that is, living organisms have the ability to selectively accumulate and absorb elements). More than 90% of the chemical composition accounts for four elements: C, O, N, H, which are involved in the formation of complex organic molecules (proteins, nucleic acids, carbohydrates, lipids).
2. Cellular structure (Unity of structural organization). All organisms on Earth are made up of cells. There is no life outside the cell.
3. Metabolism (Openness of living systems). All living organisms are “open systems”.
The openness of a system is a property of all living systems associated with a constant supply of energy from the outside and the removal of waste products (an organism is alive as long as there is an exchange of substances and energy with the environment in it).
Metabolism is a set of biochemical transformations occurring in the body and other biosystems.
In living organisms, processes of two types occur simultaneously: assimilation, that is, the formation of complex organic substances, and dissimilation, that is, the decay of organic substances, proceeding with the release of energy. Metabolism ensures the constancy of the chemical composition in continuously changing environmental conditions.
4. Self-reproduction (Reproduction) – the ability of living systems to reproduce their own kind. The ability to reproduce itself is the most important property of all living organisms. It is based on the process of doubling DNA molecules with subsequent cell division.
5. Self-regulation (Homeostasis) – maintaining the constancy of the internal environment of the body in continuously changing environmental conditions. Any living organism maintains homeostasis (the constancy of the internal environment of the body). Persistent violation of homeostasis leads to the death of the organism.
6. Development and growth. The development of a living is represented by the individual development of an organism (ontogeny) and the historical development of living nature (phylogeny).
- In the process of individual development, the individual properties of the organism are gradually and consistently manifested and its growth is carried out (all living organisms grow during their life).
- The result of historical development is the general progressive complication of life and the whole variety of living organisms on Earth. Development is understood as both individual development and historical development.
7. Irritability – the body’s ability to selectively respond to external and internal stimuli (reflexes in animals; tropisms, taxis and nastia in plants).
8. Heredity and variability are factors of evolution, as they give rise to material for selection.
Variability is the ability of organisms to acquire new traits and properties as a result of the influence of the external environment and / or changes in the hereditary apparatus (DNA molecules).
Heredity is the ability of an organism to pass on its traits to subsequent generations.
9. Ability to adapt – in the process of historical development and under the influence of natural selection, organisms acquire adaptations to environmental conditions (adaptation). Organisms that do not have the necessary adaptations are dying out.
10. Integrity (continuity) and discreteness (discontinuity). Life is holistic and discrete at the same time. This pattern is inherent in both structure and function.
Any organism is an integral system, which at the same time consists of discrete units – cellular structures, cells, tissues, organs, organ systems. The organic world is integral, since all organisms and processes occurring in it are interconnected. At the same time, it is discrete, since it consists of individual organisms.
Some of the properties listed above may be inherent in inanimate nature.
Example: for living organisms, growth is characteristic, but crystals of some substances also grow! However, crystal growth occurs in a completely different way, it is not based on the process of cell division.
Example: when any substance burns, metabolism and energy conversion occurs, but self-regulation and reproduction does not occur.
Consequently, all the properties listed above are characteristic of living organisms only in their totality.