The following levels of life organization are distinguished: molecular, cellular, organ-tissue (sometimes they are separated), organismal, population-species, biogeocenotic, biosphere. Living nature is a system, and the various levels of its organization form its complex hierarchical structure, when the underlying simpler levels determine the properties of the higher ones.

So complex organic molecules are part of cells and determine their structure and vital functions. In multicellular organisms, cells are organized into tissues, and several tissues form an organ. A multicellular organism consists of organ systems; on the other hand, the organism itself is an elementary unit of a population and a biological species. A community is represented by interacting populations different types. The community and environment form a biogeocenosis (ecosystem). The totality of planet Earth's ecosystems forms its biosphere.

At each level, new properties of living things arise that are absent at the underlying level, and their own elementary phenomena and elementary units are distinguished. At the same time, in many ways the levels reflect the course of the evolutionary process.

The identification of levels is convenient for studying life as a complex natural phenomenon.

Let's take a closer look at each level of life organization.

Molecular level

Although molecules are made up of atoms, the difference between living and nonliving matter begins to appear only at the molecular level. Only living organisms contain a large number of complex organic substances - biopolymers (proteins, fats, carbohydrates, nucleic acids). However, the molecular level of organization of living things also includes inorganic molecules that enter cells and play an important role in their life.

The functioning of biological molecules underlies a living system. At the molecular level of life, metabolism and energy conversion are manifested as chemical reactions, transmission and change of hereditary information (reduplication and mutations), as well as a number of other cellular processes. Sometimes the molecular level is called molecular genetic.

Cellular level of life

It is the cell that is the structural and functional unit of living things. There is no life outside the cell. Even viruses can exhibit the properties of a living thing only when they are in the host cell. Biopolymers fully demonstrate their reactivity being organized into a cell, which can be considered as complex system interconnected primarily by various chemical reactions of molecules.

On this cellular level the phenomenon of life manifests itself, the mechanisms of transmission of genetic information and the transformation of substances and energy are coupled.

Organ-tissue

Only multicellular organisms have tissues. Tissue is a collection of cells similar in structure and function.

Tissues are formed in the process of ontogenesis by differentiation of cells having the same genetic information. At this level, cell specialization occurs.

Plants and animals have different types of tissues. So in plants it is a meristem, protective, basic and conductive tissue. In animals - epithelial, connective, muscular and nervous. Tissues may include a list of subtissues.

An organ usually consists of several tissues interconnected into a structural and functional unity.

Organs form organ systems, each of which is responsible for an important function for the body.

The organ level in unicellular organisms is represented by various cell organelles that perform the functions of digestion, excretion, respiration, etc.

Organismic level of organization of living things

Along with the cellular level, separate structural units are distinguished at the organismal (or ontogenetic) level. Tissues and organs cannot live independently, organisms and cells (if this single cell organism) can.

Multicellular organisms are made up of organ systems.

At the organismal level, such life phenomena as reproduction, ontogenesis, metabolism, irritability, neurohumoral regulation, and homeostasis are manifested. In other words, its elementary phenomena constitute the natural changes of the organism in individual development. The elementary unit is the individual.

Population-species

Organisms of the same species, united by a common habitat, form a population. A species usually consists of many populations.

Populations have a common gene pool. Within a species, they can exchange genes, i.e. they are genetically open systems.

Elementary evolutionary phenomena occur in populations, ultimately leading to speciation. Living nature can evolve only at supraorganism levels.

At this level, the potential immortality of the living arises.

Biogeocenotic level

Biogeocenosis is an interacting set of organisms of different species with various environmental factors. Elementary phenomena are represented by matter-energy cycles, provided primarily by living organisms.

The role of the biogeocenotic level is the formation of stable communities of organisms of different species, adapted to living together in a certain habitat.

Biosphere

The biosphere level of life organization is a system higher order life on Earth. The biosphere covers all manifestations of life on the planet. At this level, there is a global circulation of substances and a flow of energy (encompassing all biogeocenoses).

Life on Earth originated over a long period of time. It arose under the influence of various complex factors, which over time led not only to the emergence of life, but also to its manifestation in different forms. Thus, the complexity of the formation conditions led to the fact that wildlife is structured from various systems, which, combined and subordinate to each other, form a multi-level integral structure, which is unthinkable without one of the links.

Basic levels of organization of living nature

To correctly understand this system, you need to understand that the proposed ones are subordinate. Each of them can be considered as a separate system or subsystem, but a holistic perception of the levels of life with biological point vision is very important in mastering this material.

Levels of organization of living nature and their characteristics

Before moving on to the description, we note that there is no universal list of biosystems, and the one we propose is the most general: 8 levels of organization are presented here.

• Levels of organization of living nature: molecular and cellular

Molecular. level, which is the boundary between elementary units; proteins, carbohydrates, nucleic acids, lipids, etc. It is here that the transfer of genetic information occurs, biosynthesis and energy conversion occur. Encoding information is the main task of the molecular level, which, in turn, has two components: organic molecules and inorganic compounds, as well as complexes chemical compounds.

Cellular. Here the elements are cellular associations - organelles. It is responsible for the reproductive function, participates in the regulation chemical reactions, and this is also where energy consumption occurs. It consists of one component - a complex of molecules of chemical compounds. At this level, biosynthesis, cell division and photosynthesis occur.

• Levels of organization of living nature: tissue and organ

Fabric. It is represented by tissues that unite various cells that have an identical structure. Tissues are created in the process of ontogenesis due to different groups. They differ in animals and plants, due to the specialization of cells.

Organ. In this system, the elements are the organs of organisms. In some cases, entire organ systems can be observed (in more advanced organisms), and in protozoa, movement, respiration, digestion, etc., are carried out at the expense of individual organelles.

• Levels of organization of living nature: organismal and population-species

Organic. This is characteristic of unicellular and multicellular organisms. Here it is possible in various ways nutrition, a different structure is found (animals, birds, fungi, bacteria). Here the connection between the organism and its environment is revealed, which also participates in the formation of structural features. The main component is the cell.

Population-species. Represented by kinship, which forms populations, and these, in turn, into species. The main functions of this level are birth and death rates, numbers, and densities. Here a strong connection between the species and its habitat is established.

• Levels of organization of living nature: biogeocenotic and biosphere

Biogeocenotic. This level is also referred to as the "ecosystem" level. Here we see the organization of life from the point of view of population: this is a wide scope of creatures of the same type (similar). The ecosystem level has many properties: population structure, types, quantitative and species composition. The main components are: environmental features and food systems.

Biosphere. This highest form ecosystem organization. The main elements are: ecosystems and their environment, which means soil, atmosphere, hydrosphere and other global parameters. Here there is an interaction between living and nonliving things, as well as the circulation of substances.

The level of organization of living matter is the functional place of a biological structure of a certain degree of complexity in the general hierarchy of living things. The following levels of organization of living matter are distinguished.

Molecular(molecular genetic). It includes the method of existence and self-reproduction of complex informational organic molecules, high-molecular organic compounds such as proteins, viruses, plasmids, nucleic acids, etc.

Subcellular(supramolecular). At this level, living nature is organized into organelles: chromosomes, cell membrane, endoplasmic reticulum, mitochondria, Golgi complex, lysosomes, ribosomes and other subcellular structures.

Cellular. At this level, living nature is represented by cells, i.e. elementary structural and functional unit of living things.

Organo-tissue. At this level, living nature is organized into tissues and organs. Tissue is a collection of cells similar in structure and function, as well as intercellular substances associated with them. An organ is a part of a multicellular organism that performs a specific function or functions.

Organismal(ontogenetic). At this level, living nature is represented by organisms. An organism (individual, individual) is an indivisible unit of life, its real carrier, characterized by all its characteristics.

6. Population-widow. At this level, living nature is organized into populations. Population is a collection of individuals of the same species, forming a separate genetic system that exists for a long time in a certain part of the range, relatively separately from other populations of the same species. Species is a set of individuals (populations) capable of interbreeding to form fertile offspring and occupying a certain area (area) in nature.

Biocenotic. At this level, living nature forms biocenoses - a collection of populations of different species living in a certain territory.

Biogeocenotic. At this level, living nature forms biogeocenoses - a combination of biocenosis and abiotic environmental factors (climate, soil).

Biosphere. At this level, living nature forms the biosphere - the shell of the Earth, transformed by the activity of living organisms.

It is just as impossible to predict the properties of each next level based on the properties of previous levels as it is to predict the properties of water based on the properties of oxygen and hydrogen. This phenomenon is called " emergence", i.e. the presence of special, qualitatively new properties in a system that are not inherent in the sum of the properties of its individual elements. On the other hand, knowledge of the features of the individual components of the system greatly facilitates its study.

7.4. Properties of living systems

Russian physicist M.V. Volkenstein proposed the following definition of life: “Living bodies that exist on Earth are open, self-regulating and self-reproducing systems built from biopolymers - proteins and nucleic acids.” However, there is still no generally accepted definition of the concept of “life”. Nevertheless, it is possible to identify signs (properties) of living matter that distinguish it from nonliving matter.

1. A certain chemical composition. Living organisms are made up of the same chemical elements, as objects of inanimate nature, but the ratio of these elements is different. The macroelements of living beings are carbon (C), oxygen (O), nitrogen (N) and hydrogen (H) (in total, about 98% of the composition of living organisms), as well as calcium (Ca), potassium (K), magnesium (Mg) , phosphorus (P), sulfur (S), sodium (Na), chlorine (Cl), iron (Fe) (about 1–2% in total). Chemical elements that are part of living organisms and at the same time perform biological functions are called biogenic. Even those that are contained in cells in negligible quantities: manganese (Mn), cobalt (Co), zinc (Zn), copper (Cu), boron (B), iodine (I), fluorine (F), etc. . – and their total content in living matter is about 0.1%, cannot be replaced by anything and is absolutely necessary for life.

Chemical elements are part of cells in the form of ions and molecules of inorganic and organic substances. The most important organic matter in the cell - water (75–85% of the wet weight of living organisms) and mineral salts (1–1.5%), the most important organic substances – carbohydrates (0.2–2.0%), lipids (1–5%), proteins (10–15%) and nucleic acids (1–2%).

Cellular structure. All living organisms, except viruses, have a cellular structure.

Metabolism (metabolism) and energy dependence. Living organisms are open systems; they depend on input from external environment substances and energy. Living beings are able to use two types of energy - light and chemical, and therefore are divided into two groups: phototrophs (organisms that use light energy for biosynthesis - plants, cyanobacteria) and chemotrophs (organisms that use the energy of chemical reactions of oxidation of inorganic compounds for biosynthesis - nitrifying bacteria, iron bacteria, sulfur bacteria, etc.). Depending on the sources of carbon, living organisms are divided into autotrophs (organisms capable of creating organic substances from inorganic substances - plants, cyanobacteria), heterotrophs (organisms that use organic compounds as a carbon source - animals, fungi and most bacteria) and mixotrophs (organisms that They can both synthesize organic substances from inorganic ones and feed on ready-made organic compounds (insectivorous plants, representatives of the euglena algae division, etc.).

Nutrients that enter the body are involved in metabolic processes - metabolism. There are two components of metabolism - catabolism and anabolism.

Catabolism(energy metabolism, dissimilation) is a set of reactions leading to the formation of simple substances from more complex ones (hydrolysis of polymers to monomers and the breakdown of the latter to low molecular weight compounds of carbon dioxide, water, ammonia and other substances). Catabolic reactions usually occur with the release of energy. The energy released during the breakdown of organic substances is not immediately used by the cell, but is stored in the form of high-energy compounds, usually in the form of adenosine triphosphate (ATP). ATP synthesis occurs in the cells of all organisms during the process of phosphorylation, i.e. addition of inorganic phosphate to ADP. Catabolism is divided into several stages

The preparatory stage consists of breaking down complex carbohydrates into simple ones: glucose, fats into fatty acids and glycerol, proteins into amino acids.

The oxygen-free stage of respiration is glycolysis, as a result of which glucose is broken down into pyruvic acid (PVA); As a result, ATP is formed (from 1 mole of glucose). In anaerobes or aerobes, fermentation occurs when there is a lack of oxygen.

The oxygen stage is respiration, i.e. complete oxidation of PVC occurs in the mitochondria of eukaryotes in the presence of oxygen and includes two stages: a chain of sequential reactions - the Krebs cycle (cycle tricarboxylic acids) and electron transfer cycle; As a result, 36 ATP is formed (from 1 mole of glucose).

Anabolism(plastic exchange, assimilation) is a concept opposite to catabolism: a set of reactions for the synthesis of complex substances from simpler ones (the formation of carbohydrates from carbon dioxide and water during photosynthesis, matrix synthesis reactions). Anabolic reactions require energy expenditure to occur. The most important metabolic process of plastic metabolism is photosynthesis (photoautotrophy) - the synthesis of organic compounds from inorganic ones using light energy.

Self-regulation (homeostasis). Living organisms have the ability to maintain homeostasis - the constancy of their chemical composition and the intensity of metabolic processes.

5. Irritability. Living organisms exhibit irritability, i.e. the ability to respond to certain external influences with specific reactions. The reaction of multicellular animals to irritation is carried out with the participation of the nervous system - reflex. The reaction to irritation in the simplest animals is called taxis, which is expressed in a change in the nature and direction of movement. In relation to the stimulus, phototaxis is distinguished - movement under the influence of a light source, chemotaxis - movement of the body depending on the concentration of chemicals, etc. There are positive or negative taxis depending on how the stimulus acts on the body: positively or negatively. The reaction to irritation in plants - tropism - is expressed in a certain growth pattern. Thus, heliotropism means the growth of above-ground parts of plants (stems, leaves) towards the Sun, and geotropism means the growth of underground parts (roots) towards the center of the Earth.

Heredity. Living organisms are capable of transmitting unchanged characteristics and properties from generation to generation with the help of information carriers - DNA and RNA molecules.

Variability. Living organisms are capable of acquiring new characteristics and properties. Variability creates a variety of starting material for natural selection, i.e. selection of the most adapted individuals to specific living conditions in natural conditions, which in turn leads to the emergence of new forms of life and new species of organisms.

Self-reproduction (reproduction). Living organisms are capable of reproducing - reproducing their own kind. Thanks to reproduction, the change and continuity of generations occurs.

It is customary to distinguish between two main types of reproduction: asexual and sexual.

Individual development (ontogenesis). Each individual is characterized by ontogenesis - individual development organism from birth to the end of life (death or new division). Development is accompanied by growth.

Evolutionary development (phylogeny). Living matter as a whole is characterized by phylogeny - historical development life on Earth from its origin to the present.

Adaptations. Living organisms are capable of adapting, i.e. adapt to conditions environment.

Rhythm. Living organisms exhibit rhythmic activity (daily, seasonal, etc.).

Integrity and discreteness. On the one hand, all living matter is holistic, organized in a certain way and subject to general laws; on the other hand, any biological system consists of separate, although interconnected, elements. Any organism or other biological system (species, biocenosis, etc.) consists of individual isolated, i.e. isolated or delimited in space, but closely connected and interacting with each other, parts that form a structural and functional unity.

Hierarchy. Starting from biopolymers (proteins and nucleic acids) and ending with the biosphere as a whole, all living things are in a certain subordination. The functioning of biological systems at a less complex level makes the existence of a more complex level possible.

Negentropy. According to the second law of thermodynamics, all processes occurring spontaneously in isolated systems develop in the direction of decreasing order, i.e. entropy increase. At the same time, as living organisms grow and develop, on the contrary, they become more complex, which does not contradict the second law of thermodynamics, since living organisms are open systems. Organisms feed, absorbing energy from the outside, release heat and waste products into the environment, and finally die and decompose. According to the figurative expression of E. Schrödinger, “the body feeds on negative entropy.” As organisms improve and become more complex, they bring chaos to the world around them.

Let's figure out what the system is. A system is an ordered whole that consists of interconnected parts.
Biological systems are organized depending on a hierarchy that cannot be violated, since everything within the system is integral. If we compare systems at different levels, we will be able to notice many similarities between them or highlight the special features of each level of the system.
It is customary to distinguish different levels of biosystems and each of them is characterized by properties that do not exist at the underlying levels. Children, let's take a close look at Figure 1. What levels of organization of living matter are distinguished in biology?

Rice. 1 Levels of organization of living matter
The biogeocenotic level is distinguished by its specificity, which is associated with its internal components and the cycle of substances, and the biosphere level is distinguished by the closed nature of the cycles of substances.
Let's look separately at each of the existing levels of the hierarchy of a biological system. Guys, I suggest using the following

video 1 “Laws of ecosystem organization”

YouTube Video

and Figure 2, begin to study each level of organization of living matter.


Rice. 2 What do we know about the levels of organization of all life on Earth?
1.Molecular level.

Rice. 3 Molecules - the basis of the molecular level
Chemicals, nucleic acids, proteins, carbohydrates, lipids are the smallest units of this level of life organization. In Figure 3 you can see the smallest particles that are the basis of this level of organization of living matter.
Here we see the manifestation of such important processes of nature as the transmission of hereditary information through DNA, energy conversion and biosynthesis. The main strategy of life at this level is that living matter capable of creating living things, can encode data that was acquired in changing environmental conditions.
2. Cellular level.


Rice. 4 Cells - the basis of the cellular level
At this level, the main elements are various organelles. In Figure 4 you can see cells and their organelles, which are the basis of this level of organization of living matter.
The main processes at this level are the ability to reproduce itself, the inclusion of most chemical elements in the cell, the regulation of chemical reactions, and the supply and consumption of energy. The strategy of life is expressed in the fact that living systems include the chemical elements of the Earth and the energy of the Sun.
3.Tissue level.
What is fabric? Tissue is a collection of cellular elements of different types of cells and intercellular substance, which performs a separate specific function in the body.

4. Organ level.
An organ is a collection of tissues that are interconnected by the fact that they perform communal functions and have their own specific place in the body.

Control block No. 1

1) What is a biological system?
2) Why are there several types in the system hierarchy?
3) How many and what damage can you name?

Part 2. Organismal, population-species, ecosystem and biosphere levels of organization of living matter.

Let's continue our acquaintance with the levels of living matter.
5. The organismal level is characteristic of unicellular and multicellular biosystems(plants, fungi, animals, humans and various microorganisms). In Figure 5 you can see the organisms that are inherent in this level of organization.


Rice. 5 Organismal level and food chains
At this level, living organisms have the following properties: nutrition, respiration, excretion, irritability, growth and development, reproduction, behavior, life expectancy, relationships with the environment. All of the above as a whole characterizes it as an integral self-regulating biosystem. Here the life strategy is that the organism strives to survive in any changing environmental conditions.

Rice. 6Population-species level
The population-species level organizes individuals related to each other in the population. Populations are then grouped into species and new properties emerge. In Figure 6 you can see the populations of organisms that are inherent to this level of organization.
The main properties of this level we can call birth rate, mortality, survival, structure (gender, age, environmental), density, number, functioning in nature. The strategy of the population-species level is a more complete use of the capabilities of the natural habitat, in the pursuit of the longest possible existence, in preserving the properties of the species and independent development.
7. Biogeocenotic (ecosystem) level characterized by the fact that populations various types become the main structural elements. In the table in Figure 7 you can see the structure of this level of organization.


Rice. 7 Ecosystem level
Here we can highlight a lot of properties inherent in species populations. These include: food chains and networks, ecosystem structure, species and quantitative composition its population, trophic levels, types of biotic relationships, productivity, energy, sustainability.
Guys, let's watch the following video to understand the essence of food chains in an ecosystem.

Video 2 “Food connections of the ecosystem”

YouTube Video

The manifestations of life on our planet are extremely diverse. In this regard, various levels of organization of living matter are distinguished, which reflect the subordination and hierarchy of the structural organization of life. The concept of levels of organization is based on the principle of discreteness.

Molecular level. The elementary units of this level of life organization are chemicals: nucleic acids, proteins, carbohydrates, lipids, etc. At this level, such important life processes as the transfer of hereditary information, biosynthesis, energy conversion, etc. are mainly manifested. The main strategy of life at the molecular level is the ability to create living matter and encode information, acquired in changing environmental conditions.

On cellular at the organizational level, the structural elements are various organelles. The ability to reproduce one’s own kind, the inclusion of various chemical elements of the Earth into the composition of the cell, the regulation of chemical reactions, the storage and consumption of energy are the main processes of this level. The strategy of life at the cellular level is the involvement of the chemical elements of the Earth and the energy of the Sun into living systems.

Organismal the level of organization is inherent in unicellular and multicellular biosystems (plants, fungi, animals, including humans and various microorganisms). Living organisms exhibit such properties as nutrition, respiration, excretion, irritability, growth and development, reproduction, behavior, life expectancy, and relationships with the environment. All of these processes together characterize the body as an integral self-regulating biosystem. The main strategy of life at this level is the orientation of the organism (individual) towards survival in constantly changing environmental conditions.

Population-species The level of organization is characterized by the unification of related individuals into populations, and populations into species, which leads to the emergence of new properties of the system. The main properties of this level: fertility, mortality, survival, structure (gender, age, environmental), density, number, functioning in nature. The main strategy of the population-species level is manifested in a more complete use of the capabilities of the habitat, in the desire for the longest possible existence, in preserving the properties of the species and independent development.

On biogeocenotic (ecosystem) level of organization, the main structural elements are populations of different species. This level is characterized by many properties. These include: the structure of the ecosystem, the species and quantitative composition of its population, types of biotic connections, food chains and networks, trophic levels, productivity, energy, sustainability, etc. Organizing properties are manifested in the circulation of substances and the flow of energy, self-regulation and stability, autonomy, openness of the system, seasonal changes. The main strategy of this level is the active use of the entire diversity of the environment and the creation of favorable conditions for the development and prosperity of life in all its diversity.

The most high level organization of life is biosphere. The main structural units of this level are biogeocenoses (ecosystems) and their environment, i.e. geographic envelope of the Earth (atmosphere, hydrosphere, soil, solar radiation etc.) and anthropogenic impact. For this level, the organ and organizations are characterized by: active interaction of living and nonliving matter of the planet; biological circulation of substances and energy flows with geochemical cycles included in it; economic and ethnocultural activities of humans. Basic life strategy biosphere level- the desire to ensure the dynamic stability of the biosphere as the largest ecosystem on our planet.