What are biological systems? Biological systems: signs, properties, organization

The concept of a systemic multilevel organization of life is one of the key in modern natural science. All biological objects, according to it, are united on the basis of certain features and close relationships and are built in a certain hierarchical order. Similar principles are universal for the whole of nature as a whole. Acquaintance with what biological systems are, it is better to begin with the definition of a key concept.

Comprehensive theory

The foundations of the concept were laid in the middle of the last century by Ludwig von Bertalanffy. It was he who developed the general theory of systems. It covers all objects of nature and society. The theory identifies biological, social, cosmic, physical, economic and other systems that combine into three major categories: the microcosm, the macrocosm and megalore. The first include elementary particles and atoms, to the second - everything from molecules to oceans and continents, to the third - space objects. The macrocosm also includes living systems.

The basic concept

The system is a union of elements, based on certain relationships, subject to certain laws. The organization of such a structure, as a rule, consists of several ordered levels. In this case, each element can simultaneously be a system of a lower order. An important property of such an organization: the whole is qualitatively different from the sum of all its components. The system is not just a set of characteristics of elements, it is distinguished by some new quality.

All objects of the living world are similar structures. And the quality that arises from the combination of several elements becomes a new manifestation of life.

Open

Understanding what biological systems are, requires the description of another property of similar structures. This interaction with the environment. In theory, the organization of biological systems can be both closed and open. In practice, scientists do not know of any completely closed structure. Any living system constantly interacts with the environment through some semi-permeable boundary shell. Cells have a bilipid membrane, and a space station has a skin. Social systems are united through legislative acts or certain relationships of people.

It turns out that the answer to the question "What are biological systems?" Can be formulated as follows: it is a set of constantly interacting living elements, built in a certain hierarchical order and open to varying degrees to exchange with the environment.

Symptoms

All the distinctive characteristics of the structures under consideration are simultaneously the criteria for distinguishing living nature from the inanimate one. Let's call the signs of biological systems with their brief characteristics:

1. Single chemical composition. All natural objects are built from the same molecules. However, living matter as the main elements includes carbon, nitrogen, oxygen and hydrogen.
2. Metabolism with the medium. This is already described the property of openness of the system. One of its manifestations is the energy dependence of such structures.
3. Reproduction (reproduction).
4. Heredity is the property of transferring features of structure and functioning from generation to generation.
5. Variability is the property of acquiring new characteristics and skills throughout life.
6. Growth and development. Represents a directional irreversible change. Isolate the individual and historical development of living systems, called ontogeny and phylogeny, respectively.
7. Irritability (reflexes, taxis) is a property to react to stimuli and changes in the environment.
8. Discreteness. Any living system consists of separate, but interacting elements that form a hierarchical structure.
9. Self-regulation. There are internal mechanisms for maintaining homeostasis, contributing to the survival of the system. Self-regulation is based on the principle of negative feedback.
10. Rhythm. Strengthening and weakening of various processes at regular intervals.

Levels of organization of biological systems

All described properties are preserved at any stage of the hierarchical structure. The main levels of organization of biological systems are fairly arbitrary, since any of them can easily be divided into several components. In general, there are four stages of this hierarchy:

• Molecular-genetic level;
• Ontogenetic level;
• Population-specific level;
• Biogeocoenotic level.

Let us dwell on them in more detail.

Molecular-genetic level

Such macromolecules as proteins, lipids, carbohydrates and nucleic acids are structural elements of organisms, but in and of themselves are not carriers of a full life.

Each of these elements performs its functions. Carbohydrates are a source of energy. Lipids are part of the plasma membrane of cells. They are also an energy supplier. Proteins perform most of life's functions. They consist of twenty varieties of amino acids, which can alternate in random order. As a result, there is a huge amount of proteins that can cope with very different jobs. Nucleic acids, DNA and RNA are the basis of heredity.

Macromolecules are combined into complexes, forming cell organelles: ribosomes, mitochondria, myofibrils and so on. All of them are responsible for individual biological manifestations, but do not reach the level of complexity that can be called life.

Next step

What biological systems make up the ontogenetic level? These are all organisms, beginning from unicellular and ending with mammals and man, as well as organs, tissues and cells of the body. All these elements can be considered as separate levels of organization of biological systems, but for convenience and by virtue of general laws they are combined.

A cell is an elementary structural unit of the structure of organisms. It also represents the level of complexity of the biological system on which life first appears as a phenomenon. As already mentioned, simpler structures provide only separate functions. Cage is inherent in all the properties of biological systems.

Tissues and organs are intermediate sublevels of the ontogenetic stage. A multicellular organism follows them. It is characterized by the ability to independent existence, development and reproduction. This property distinguishes the individual and the cell from organs and tissues.

Population and species

From step to step, biological systems become more complex. At the next level, species and populations are located. The first are a set of individuals characterized by hereditary similarity in a number of parameters: morphology, physiology, genetics, geographical location. And most importantly: the organisms that make up the species are able to freely interbreed and leave fertile offspring.

The group of individuals occupies a certain territory, which is called the habitat area. Quite often it is torn apart by various geographical obstacles. As a result, the species breaks up into several relatively isolated populations. Naturally, the conditions of separation from the rest of the species contribute to the accumulation of a certain genetic material. With a strong divergence of the characteristics of populations, new species appear.

Ecosystems

In the hierarchical ladder behind populations and species follows the community, biogeocenosis and the biosphere. The first is a collection of populations of different species located on the same territory. Isolate plant, animal and microbial communities. Their totality within a single area will be called a biocenosis. These levels of biological systems are characterized by a close interconnection of all individuals.

The conditions in which organisms exist are constantly influencing them. The whole set of similar factors of the inanimate nature of this range is usually called the biotope. The environment and communities of organisms are in constant interaction, there is a cycle of matter and energy. Therefore, the biotope and biocenosis are combined into a biogeocenosis, or ecosystem. This level is also characterized by all the features of the living: it is constantly in contact with the environment, management in it occurs on the principle of self-regulation, the processes are subject to certain cycles.

At the highest level of the hierarchy is the Earth's biosphere-a shell inhabited by living beings. Human activity exerts a huge influence on it, which increasingly leads to the emergence of environmental disasters.

What are biological systems? In fact, it's all the living things that surround us. Man differs from other elements in the biosphere in the ability to be aware, and therefore redirect and change his activities. While this ability Homo sapiens works against nature. However, thanks to her, we have a chance to fix everything.