Signs, properties and criteria of living systems. What is a living system?

For a long time scientists have tried to define life. But this is difficult to do, because the organisms that inhabit the planet are very diverse. What are the criteria of living systems and the features of their functioning, you will learn from our article.

What is the system

A system is a collection of elements that are connected in a certain sequence. Such a structure ensures their integrity and ability to function. By origin, systems are artificial and natural. The first include all the structures that the person created. Examples of them are diverse: from a ballpoint pen to a skyscraper. Agree, in the first and second cases all the components of these systems are subject to clear laws and unite in a certain order. Their slightest violation can change the whole mechanism of work.

Live systems are all the structures that surround us, but were not created by man. They are the "works" of nature. Microscopic cells of amoeba, giant coniferous trees, huge blue whales - all these are living systems. In these organisms, there really are many elements that interact in a certain way with each other. And what are the criteria of living systems in general? And does the protein globules or molecules of water refer to this concept? After all, they also consist of separate elements, connected in a certain sequence. Scientists affirm unambiguously that life is only a totality of elements enclosed in a cellular structure.

Levels of organization of living systems

Live systems in nature exist at different levels of the organization, which differ in the features of the structure and interactions between their components. Molecular is also one of them, but its independent existence outside the cell is impossible. The most important process occurring at this level is the storage and sale of genetic material. Criteria of living systems are most evident on the example of a cell. It is the structural and functional unit of all living things. The cells consist of plants, animals, fungi and bacteria. Exceptions are viruses, which are a combination of nucleic acid and protein molecules.

Further, the living systems become more complex. Cells are combined into tissues. Each of them specializes in the performance of a specific function. The totality of tissues represents the next level - the organism. However, in nature, individuals do not exist in isolation. They interact with each other and with factors of inanimate nature. At the same time, they consistently form a population-species, biogeocenotic and biospheric levels. The latter is the most global, uniting absolutely all living organisms inhabiting all habitats.

Features of the chemical composition

The basic properties of living systems, regardless of the level of their organization, are characterized, first of all, by a certain chemical composition. Four chemical elements form the basis of these structures. They are carbon, oxygen, nitrogen and hydrogen. They are also called organogenic. They, in turn, form molecules of biopolymers - proteins, carbohydrates, lipids and nucleic acids.

Metabolism

Any living organism is an open system. This means that there is a continuous exchange of substances with the environment. The intake of substances, their transformation, the derivation of the final products of metabolism are indispensable signs of living systems. Entering the body, complex molecules split with the release of a certain amount of energy. It is necessary for the realization of growth and development.

Ability to self-reproduce

The ability to reproduce or reproduce and regenerate are also the criteria of living systems. These properties provide continuity at all levels, making life possible on the planet as a whole. The methods of reproduction depend on the characteristics of the structure of the biological species. For example, bacteria multiply by dividing cells in two, plants - vegetatively and with the help of spores, and animals - sexually.

Regeneration helps many organisms to maintain their vitality as long as possible. To restore lost or damaged parts of the body can coelenterates, worms, reptiles and plants. Especially actively divide cells of freshwater hydra, whose body can recover from 1/200 parts.

Motion

No wonder they say that movement is life. And indeed, moving in space, animals seek food, individuals of the opposite sex or better conditions for existence. Their unicellular representatives move with the help of organelles - flagella, pseudopodia or cilia. Surprisingly, plants are also capable of movement. Everyone watched the leaves and flowers turn towards the light, and the vines of the lianas twist around any surface. This is the growth of plant growth.

Growth and development

Growth and development are integral properties of living systems. The first involves quantitative changes in organisms. Growth is due to cell division. And he has unlimited plants. This means that they grow throughout life. But animals - only up to a certain period. Growth is accompanied by quantitative changes in the body - development. This process consists in the acquisition of increasingly complex features of organization and physiology. The level of development of organisms depends on their position in the system of the organic world. For example, angiosperms have become widespread due to progressive features of the structure, which include the presence of a flower and double fertilization.

Irritability

Another sign of living systems is their ability to respond to any changes in the environment. This property is called irritability. So, the flowers of the tulips open in the heat, and the leaves of the mimosa are formed during the touch. In animals, the irritability is realized by the nervous system and manifests itself in the form of reflexes. Some of them are congenital. These include respiratory, protective, grasping, sucking, blinking reflexes. They provide vitality from the first minutes of life. In the course of changes in existence, animals acquire new behavioral responses.

The properties of living systems ensure their existence throughout their individual and historical development. These include the cellular structure, the unity of the chemical composition, metabolism, the ability to reproduce, grow, develop, irritability and adaptation.