What are the biological sciences? Biology

The importance of biology for medicine:

Genetic research has made it possible to develop methods early diagnosis, treatment and prevention of hereditary human diseases;

Selection of microorganisms makes it possible to obtain enzymes, vitamins, hormones necessary for the treatment of a number of diseases;

Genetic engineering allows the production of biologically active compounds and drugs;

Definition of the concept of “life” at the present stage of science. Fundamental Properties alive: It is quite difficult to give a complete and unambiguous definition of the concept of life, given the huge variety of its manifestations. Most definitions of the concept of life, which were given by many scientists and thinkers over the centuries, took into account the leading qualities that distinguish living from non-living. For example, Aristotle said that life is the “nutrition, growth and decrepitude” of the body; A. L. Lavoisier defined life as a “chemical function”; G. R. Treviranus believed that life is “a stable uniformity of processes with differences external influences" It is clear that such definitions could not satisfy scientists, since they did not (and could not reflect) all the properties of living matter. In addition, observations indicate that the properties of living things are not exceptional and unique, as it seemed before; they are separately found among inanimate objects. A.I. Oparin defined life as “a special, very complex form of movement of matter.” This definition reflects the qualitative uniqueness of life, which cannot be reduced to simple chemical or physical laws. However, in this case too the definition is general character and does not reveal the specific originality of this movement.

F. Engels wrote in “Dialectics of Nature”: “Life is a way of existence of protein bodies, the essential point of which is the exchange of matter and energy with environment».

For practical application, those definitions that contain the basic properties that are necessarily inherent in all living forms are useful. Here is one of them: life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to reproduce itself, self-preservation and self-regulation, metabolism, and a finely regulated flow of energy. By this definition, life is a core of order spreading through a less ordered universe.

Life exists in form open systems. This means that any living form is not closed only on itself, but constantly exchanges matter, energy and information with the environment.

2. Evolutionary-determined levels of life organization: There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organismal, population-species and ecosystem.

Molecular level of organization- this is the level of functioning of biological macromolecules - biopolymers: nucleic acids, proteins, polysaccharides, lipids, steroids. The most important life processes begin from this level: metabolism, energy conversion, transmission of hereditary information. This level is studied: biochemistry, molecular genetics, molecular biology, genetics, biophysics.

Cellular level- this is the level of cells (cells of bacteria, cyanobacteria, unicellular animals and algae, unicellular fungi, cells multicellular organisms). The cell is structural unit living, functional unit, unit of development. This level is studied by cytology, cytochemistry, cytogenetics, and microbiology.

Tissue level of organization- this is the level at which the structure and functioning of tissues is studied. This level is studied by histology and histochemistry.

Organ level of organization- This is the level of organs of multicellular organisms. Anatomy, physiology, and embryology study this level.

Organismic level of organization- this is the level of unicellular, colonial and multicellular organisms. The specificity of the organismal level is that at this level the decoding and implementation of genetic information occurs, the formation of characteristics inherent in individuals of a given species. This level is studied by morphology (anatomy and embryology), physiology, genetics, and paleontology.

Population-species level- this is the level of aggregates of individuals - populations and species. This level is studied by systematics, taxonomy, ecology, biogeography, and population genetics. At this level, the genetic and ecological characteristics of populations, elementary evolutionary factors and their impact on the gene pool (microevolution), the problem of species conservation.

Biogeocenotic level of life organization - represented by a variety of natural and cultural biogeocenoses in all living environments . Components- Populations various types; Environmental factors ; Food webs, flows of matter and energy ; Basic processes; Biochemical cycle of substances and energy flow that support life ; Fluid balance between living organisms and the abiotic environment (homeostasis) ; Providing living organisms with living conditions and resources (food and shelter). Sciences conducting research at this level: Biogeography, Biogeocenology Ecology

Biosphere level of life organization

Presented to the highest global form organization of biological systems - the biosphere. Components - Biogeocenoses; Anthropogenic impact; Basic processes; Active interaction of living and nonliving matter of the planet; Biological global circulation of matter and energy;

Active biogeochemical participation of man in all processes of the biosphere, his economic and ethnocultural activities

Sciences conducting research at this level: Ecology; Global ecology; Space ecology; Social ecology.

Classifies and describes living beings, the origin of their species, and their interactions with each other and with the environment.

As an independent science, biology emerged from the natural sciences in the 19th century, when scientists discovered that all living organisms have certain general properties and signs that are not generally characteristic of inanimate nature. The term "biology" was coined independently by several authors: Friedrich Burdach in 1800, Gottfried Reinhold Treviranus in 1802, and Jean Baptiste Lamarck in 1802.

Biological picture of the world

Currently, biology is a standard subject in secondary and higher education. educational institutions all over the world. More than a million articles and books on biology, medicine, biomedicine and bioengineering are published annually.

Cell theory is the doctrine of everything that concerns cells. All living organisms consist of at least one cell - the basic structural and functional unit of organisms. Basic mechanisms and the chemistry of all cells in all terrestrial organisms similar; cells come only from pre-existing cells that reproduce by cell division. Cell theory describes the structure of cells, their division, interaction with external environment, compound internal environment And cell membrane, mechanism of action individual parts cells and their interactions with each other.
Evolution. Through natural selection and genetic drift, the hereditary characteristics of a population change from generation to generation.
Gene theory. The characteristics of living organisms are passed on from generation to generation along with genes that are encoded in DNA. Information about the structure of living things, or genotype, is used by cells to create a phenotype, the observable physical or biochemical characteristics of an organism. Although the phenotype expressed through gene expression may prepare an organism for life in its environment, information about the environment is not passed back to the genes. Genes can change in response to environmental influences only through the evolutionary process.
Homeostasis. Physiological processes, allowing the body to maintain the constancy of its internal environment regardless of changes in the external environment.
Energy. An attribute of any living organism that is essential to its condition.

Cell theory

Evolution

A central organizing concept in biology is that life changes and develops over time through evolution, and that all known life forms on Earth have common origin. This led to the similarity of the basic units and life processes mentioned above. The concept of evolution was introduced into the scientific lexicon by Jean-Baptiste Lamarck in 1809. Charles Darwin discovered fifty years later that it driving force is natural selection, just as artificial selection is deliberately used by man to create new breeds of animals and varieties of plants. Later in the synthetic theory of evolution an additional mechanism evolutionary changes genetic drift has been postulated.

Gene theory

The form and functions of biological objects are reproduced from generation to generation by genes, which are the elementary units of heredity. Physiological adaptation to the environment cannot be encoded in genes and be inherited in offspring (see Lamarckism). It is noteworthy that everything existing forms Earthly life, including bacteria, plants, animals and fungi, have the same basic mechanisms for DNA copying and protein synthesis. For example, bacteria into which human DNA is introduced are capable of synthesizing human proteins.

The set of genes of an organism or cell is called genotype. Genes are stored on one or more chromosomes. A chromosome is a long strand of DNA that can contain many genes. If a gene is active, its DNA sequence is copied into RNA sequences through transcription. The ribosome can then use the RNA to synthesize a protein sequence corresponding to the RNA code in a process called translation. Proteins can perform catalytic (enzymatic) functions, transport, receptor, protective, structural, and motor functions.

Homeostasis

Homeostasis is the ability of open systems to regulate their internal environment so as to maintain its constancy through a variety of corrective influences directed regulatory mechanisms. All living things, both multicellular and unicellular, are capable of maintaining homeostasis. At the cellular level, for example, a constant acidity of the internal environment is maintained (). At the body level in warm-blooded animals it is maintained constant temperature bodies. In association with the term ecosystem, homeostasis refers, in particular, to the maintenance by plants and algae of a constant concentration of atmospheric oxygen and carbon dioxide on Earth.

Energy

The survival of any organism depends on a constant supply of energy. Energy is drawn from substances that serve as food and through special chemical reactions used to build and maintain cell structure and function. In this process, food molecules are used both to extract energy and to synthesize the body's own biological molecules.

The primary source of energy for the vast majority of terrestrial creatures is light energy, mainly solar energy, however some bacteria and archaea obtain energy through chemosynthesis. Light energy is converted by plants into chemical energy (organic molecules) through photosynthesis in the presence of water and some minerals. Part of the energy received is spent on increasing biomass and maintaining life, the other part is lost in the form of heat and waste products. General mechanisms The conversion of chemical energy into useful energy to support life is called respiration and metabolism.

Levels of life organization

Living organisms are highly organized structures, therefore in biology there are a number of levels of organization. IN various sources some levels are omitted or combined with each other. Below are the main levels of organization of living nature separately from each other.

Molecular - the level of interaction between the molecules that make up the cell and determine all its processes.
Cellular - the level at which cells are considered as elementary units of the structure of living things.
Tissue - the level of collections of cells similar in structure and function that form tissues.
Organ - the level of individual organs that have their own structure (combination of tissue types) and location in the body.
Organismal - the level of an individual organism.
Population-species level - the level of a population made up of a set of individuals of the same species.
Biogeocenotic - the level of interaction of species among themselves and with various factors environment.
The biosphere level is the totality of all biogeocenoses, including and determining all phenomena of life on Earth.

Biological Sciences

Most biological sciences are disciplines with a narrower specialization. Traditionally, they are grouped according to the types of organisms studied:

botany studies plants, algae, fungi and fungi-like organisms,
zoology - animals and protists,
microbiology - microorganisms and viruses.

biochemistry studies the chemical basis of life,
biophysics studies the physical basis of life,
molecular biology - complex interactions between biological molecules,
cell biology and cytology - the basic building blocks of multicellular organisms, cells,
histology and anatomy - the structure of tissues and the body from individual organs and tissues,
physiology - physical and chemical functions organs and tissues,
ethology - behavior of living beings,
ecology - interdependence various organisms and their environment,
genetics - patterns of heredity and variability,
developmental biology - the development of an organism in ontogenesis,
paleobiology and evolutionary biology - the origin and historical development of living nature.

On the borders with related sciences, the following arise: biomedicine, biophysics (the study of living objects by physical methods), biometrics, etc. In connection with the practical needs of man, such areas as space biology, sociobiology, labor physiology, and bionics arise.

Biological disciplines

History of biology

Although the concept of biology as a distinct natural science arose in the 19th century, biological disciplines had their origins earlier in medicine and natural history. Usually their tradition comes from such ancient scientists as Aristotle and Galen through the Arab physicians al-Jahiz, ibn-Sina, ibn-Zukhr and ibn-al-Nafiz. During the Renaissance, biological thought in Europe was revolutionized by the invention of printing and the spread of printed works, interest in experimental research and the discovery of many new species of animals and plants during the Age of Discovery. At this time, the outstanding minds Andrei Vesalius and William Harvey worked, who laid the foundations of modern anatomy and physiology. Somewhat later, Linnaeus and Buffon did a great job of classifying the forms of living and fossil creatures. Microscopy opened up the previously unknown world of microorganisms to observation, laying the foundation for the development of cell theory. The development of natural science, due in part to the emergence of mechanistic philosophy, contributed to the development natural history.

TO early XIX century, some modern biological disciplines, such as botany and zoology, have reached professional level. Lavoisier and other chemists and physicists began to bring together ideas about living and inanimate nature. Naturalists such as Alexander Humboldt explored the interaction of organisms with their environment and its dependence on geography, laying the foundations of biogeography, ecology and ethology. In the 19th century, the development of the doctrine of evolution gradually led to an understanding of the role of extinction and variability of species, and cell theory showed in a new light the basic structure of living matter. Combined with data from embryology and paleontology, these advances allowed Charles Darwin to create holistic theory evolution, which is based on natural selection. TO end of the 19th century centuries, the ideas of spontaneous generation finally gave way to the theory of an infectious agent as a causative agent of diseases. But the mechanism of inheritance of parental characteristics still remained a mystery.

Popularization of biology

First Founders

Significant factual material about living organisms was collected by the great physician of Greece - Hippocrates (460-377 BC). He collected information about the structure of animals and humans, and gave a description of bones, muscles, tendons, the brain and spinal cord.

The first great work zoology belongs to the Greek naturalist Aristotle (384-322 BC). He described more than 500 species of animals. Aristotle was interested in the structure and lifestyle of animals; he laid the foundations of zoology.

The first work on systematizing knowledge about plants ( botany) was made by Theophrastus (372-287 BC).

Expanding knowledge about the structure human body(anatomy) ancient science owes to the doctor Galen (130-200 BC), who performed autopsies on monkeys and pigs. His works influenced natural science and medicine for several centuries.

During the Middle Ages, under the yoke of the church, science developed very slowly. An important milestone in the development of science was the Renaissance, which began in the 15th century. Already in the 18th century. developed as independent sciences botany, zoology, human anatomy, physiology.

Major milestones in the study of the organic world

Gradually, information accumulated about the diversity of species, the structure of the body of animals and humans, individual development, functions of organs of plants and animals. Throughout the centuries-old history of biology, the largest milestones in the study organic world can be called:

Introduction of the principles of systematics proposed by K. Linnaeus;
invention of the microscope;
creation of cell theory by T. Schwann;
approval of the evolutionary doctrine of Charles Darwin;
discovery by G. Mendel of the basic laws of heredity;
application electron microscope for biological research;
transcript genetic code;
creation of the doctrine of the biosphere.

To date, science knows about 1,500,000 species of animals and about 500,000 species of plants. The study of the diversity of plants and animals, the features of their structure and life activity has great importance. Biological sciences are the basis for the development of crop production, animal husbandry, medicine, bionics, and biotechnology.

One of the oldest biological sciences is human anatomy and physiology, which form the theoretical foundation of medicine. Every person should have an understanding of the structure and functions of their body in order to be able to provide first aid if necessary, consciously take care of their health and follow hygiene rules.

Over the centuries, botany, zoology, anatomy, physiology have been developed by scientists as independent, isolated sciences. Only in the 19th century. patterns were discovered that are common to all living beings. This is how the sciences that study general patterns life. These include:

Cytology is the science of cells;
genetics - the science of variability and heredity;
ecology - the science of the relationship of an organism with the environment and in communities of organisms;
Darwinism - the science of the evolution of the organic world and others.

IN training course they make up the subject general biology.

The first major biological science is botany. She studies plants. Botany is divided into many disciplines that can also be considered biological. Algology. Plant anatomy studies the structure of plant tissues and cells, as well as the laws by which these tissues develop. Bryology studies bryophytes, dendrology studies woody plants. Carpology studies the seeds and fruits of plants.

Lichenology is the science of lichens. Mycology is about mushrooms, mycogeorgaphy is about their distribution. Paleobotany is a branch of botany that studies the fossil remains of plants. Palynology studies pollen grains and plant spores. The science of plant taxonomy deals with their classification. Phytopathology studies various diseases plants caused by pathogenic and environmental factors. Floristry studies flora, a collection of plants historically formed in a certain territory.

The science of ethnobotany studies the interactions between people and plants. Geobotany is the science of the Earth’s vegetation, of plant communities – phytocenoses. The geography of plants studies the patterns of their distribution. Plant morphology is the science of patterns. Plant physiology is about the functional activity of plant organisms.

Zoology and microbiology

Ichthyology is the science of fish, carcinology is of crustaceans, ketology is of cetaceans, conchiology is of mollusks, myrmecology is of ants, nematology is of roundworms, oology - about animal eggs, ornithology - about birds. Paleozoology studies the fossil remains of animals, planktology studies plankton, primatology studies primates, theriology studies mammals and insects, protozoology studies unicellular organisms. Ethology deals with the study.

The third major branch of biology is microbiology. This science studies living organisms invisible to the naked eye: bacteria, archaea, microscopic fungi and algae, viruses. Sections are distinguished accordingly: virology, mycology, bacteriology, etc.

Biology(from the Greek bios - life, logos - word, science) is a complex of sciences about living nature.

The subject of biology is all manifestations of life: the structure and functions of living beings, their diversity, origin and development, as well as interaction with the environment. The main task of biology as a science is to interpret all phenomena of living nature in terms of scientific basis, taking into account that the whole organism has properties that are fundamentally different from its components.

Biology studies all aspects of life, in particular the structure, functioning, growth, origin, evolution and distribution of living organisms on Earth, classifies and describes living things, the origin of their species, and their interactions with each other and with the environment.

At the core modern biology lie 5 fundamental principles:

cell theory
evolution
genetics
homeostasis
energy

Biological Sciences

Currently, biology includes a number of sciences that can be systematized according to the following criteria: subject and predominant methods research and on the subject being studied level of organization of living nature.

By subject of researchI biological sciences divided into bacteriology, botany, virology, zoology, mycology.

Botany is a biological science that comprehensively studies plants and the Earth's vegetation cover.

Zoology - a branch of biology, the science of the diversity, structure, life activity, distribution and relationship of animals with their environment, their origin and development.

Bacteriology - biological science that studies the structure and activity of bacteria, as well as their role in nature.

Virology - biological science that studies viruses.

Main object mycology are mushrooms, their structure and features of life.

Lichenology - biological science that studies lichens.

Bacteriology, virology and some aspects of mycology are often discussed as part of microbiology - section of biology, the science of microorganisms (bacteria, viruses and microscopic fungi).

Taxonomy, or taxonomy, - biological science that describes and classifies into groups all living and extinct creatures.

In turn, each of the listed biological sciences is divided into biochemistry, morphology, anatomy, physiology, embryology, genetics and systematics (plants, animals or microorganisms). Biochemistry is the science of chemical composition living matter, chemical processes, occurring in living organisms and underlying their life activity.

Morphology - biological science that studies the form and structure of organisms, as well as the patterns of their development. IN in a broad sense it includes cytology, anatomy, histology and embryology. Distinguish between the morphology of animals and plants.

Anatomy - this is a section of biology (more precisely, morphology), a science that studies internal structure and the shape of individual organs, systems and the body as a whole. Plant anatomy is considered as part of botany, animal anatomy is considered as part of zoology, and human anatomy is a separate science.

Physiology - biological science that studies the life processes of plant and animal organisms, their individual systems, organs, tissues and cells. There is physiology of plants, animals and humans.

Embryology(developmental biology)- a branch of biology, the science of the individual development of an organism, including the development of the embryo.

Object genetics are the laws of heredity and variability. Currently, it is one of the most dynamically developing biological sciences.

By the level of organization of living nature being studied allocate molecular biology, cytology, histology, organology, biology of organisms and supraorganismal systems.

Molecular biology is one of the youngest branches of biology, a science that studies, in particular, the organization of hereditary information and protein biosynthesis.

Cytology, or cell biology, - biological science, the object of study of which is the cells of both unicellular and multicellular organisms.

Histology - biological science, a branch of morphology, the object of which is the structure of tissues of plants and animals.

To the sphere organology include the morphology, anatomy and physiology of various organs and their systems. Organismal biology includes all sciences that deal with living organisms, e.g. ethology- the science of behavior of organisms.

The biology of supraorganismal systems is divided into biogeography and ecology. Studies the distribution of living organisms biogeography, whereas ecology - organization and functioning of supraorganismal systems at various levels: populations, biocenoses (communities), biogeocenoses (ecosystems) and the biosphere.

By prevailing research methods One can distinguish descriptive (for example, morphology), experimental (for example, physiology) and theoretical biology. Identification and explanation of the patterns of structure, functioning and development of living nature in various levels its organization is the task general biology. It includes biochemistry, molecular biology, cytology, embryology, genetics, ecology, evolutionary science and anthropology. Evolutionary doctrine studies the reasons driving forces, mechanisms and general patterns of evolution of living organisms. One of its sections is paleontology- a science whose subject is the fossil remains of living organisms. Anthropology- section of general biology, the science of the origin and development of man as biological species, as well as the diversity of populations modern man and the patterns of their interaction. Applied aspects of biology are classified in the field of biotechnology, breeding and other fast- developing sciences. Biotechnology is the biological science that studies the use of living organisms and biological processes in production. It is widely used in the food (baking, cheese making, brewing, etc.) and pharmaceutical industries (production of antibiotics, vitamins), for water purification, etc. Selection- the science of methods for creating breeds of domestic animals, varieties cultivated plants and strains of microorganisms with necessary for a person properties. Selection is also understood as the process of changing living organisms, carried out by humans for their needs.

The progress of biology is closely related to the successes of other natural and exact sciences, such as physics, chemistry, mathematics, computer science, etc. For example, microscopy, ultrasound (ultrasound), tomography and other methods of biology are based on physical laws, and the study of the structure of biological molecules and processes occurring in living systems would be impossible without application of chemical and physical methods. Application mathematical methods allows, on the one hand, to identify the presence of a natural connection between objects or phenomena, to confirm the reliability of the results obtained, and, on the other hand, to model a phenomenon or process. IN Lately All higher value in biology they acquire computer methods, such as modeling. At the intersection of biology and other sciences, a number of new sciences arose, such as biophysics, biochemistry, bionics, etc.

The role of biology in the formation of the modern natural science picture of the world

At the stage of its formation, biology did not yet exist separately from others natural sciences and was limited only to observation, study, description and classification of animal representatives and flora, i.e. it was a descriptive science. However, this did not prevent the ancient naturalists Hippocrates (c. 460-377 BC), Aristotle (384-322 BC) and Theophrastus (real name Tirtham, 372-287 BC). BC) make a significant contribution to the development of ideas about the structure of the human and animal bodies, as well as biological diversity animals and plants, thereby laying the foundations of human anatomy and physiology, zoology and botany. Deepening knowledge about living nature and systematizing previously accumulated facts that took place in XVI-XVIII centuries, culminated in the introduction binary nomenclature and the creation of a harmonious taxonomy of plants (C. Linnaeus) and animals (J.-B. Lamarck). Description of a significant number of species with similar morphological characteristics, as well as paleontological finds became prerequisites for the development of ideas about the origin of species and ways historical development organic world. Thus, the experiments of F. Redi, L. Spallanzani and L. Pasteur in the 17th-19th centuries refuted the hypothesis of spontaneous generation, put forward by Aristotle and prevalent in the Middle Ages, and the theory of biochemical evolution by A.I. Oparin and J. Haldane, brilliantly confirmed by S. Miller and G. Yuri, allowed us to answer the question about the origin of all living things. If the very process of the emergence of living things from non-living components and its evolution in themselves no longer raise doubts, then the mechanisms, paths and directions of the historical development of the organic world are still not fully understood, since none of the two main competing theories of evolution ( synthetic theory evolution, created on the basis of the theory of C. Darwin, and the theory of J.-B. Lamarck) still cannot provide comprehensive evidence. Application of microscopy and other methods related sciences, conditioned by progress in the field of other natural sciences, as well as the introduction of experimental practice, allowed the German scientists T. Schwann and M. Schleiden back in the 19th century to formulate cell theory, later supplemented by R. Virchow and K. Baer. It became the most important generalization in biology, which cornerstone formed the basis modern ideas about the unity of the organic world. The discovery of patterns of transmission of hereditary information by the Czech monk G. Mendel served as an impetus for the further rapid development of biology in XX-XXI centuries and led not only to the discovery of the universal carrier of heredity - DNA, but also the genetic code, as well as the fundamental mechanisms of control, reading and variability of hereditary information. The development of ideas about the environment led to the emergence of such a science as ecology, and wording teachings about the biosphere as a complex multicomponent planetary system of interconnected huge biological complexes, as well as chemical and geological processes occurring on Earth (V.I. Vernadsky), which ultimately makes it possible to reduce at least to a small extent Negative consequences economic activity person. Thus, biology played an important role in the development of modern natural science picture peace.

Methods for studying living objects

Like any other science, biology has its own arsenal of methods. Besides scientific method cognition used in other fields, methods such as historical, comparative-descriptive, etc. are widely used in biology.

Scientific method cognition includes observation, formulation of hypotheses, experiment, modeling, analysis of results and derivation of general patterns.

Observation- this is the purposeful perception of objects and phenomena using the senses or instruments, determined by the task of the activity. The main condition scientific observation is its objectivity, i.e. the ability to verify the obtained data through repeated observation or the use of other research methods, such as experiment. The facts obtained as a result of observation are called data. They can be like quality(describing smell, taste, color, shape, etc.), and quantitative, Moreover, quantitative data is more accurate than qualitative data.

Based on observational data, a hypothesis is formulated - a conjectural judgment about the natural connection of phenomena. The hypothesis is tested in a series of experiments.

An experiment is called a scientifically conducted experiment, observation of the phenomenon being studied under controlled conditions, allowing one to identify the characteristics of a given object or phenomenon. Highest form experiment is modeling - the study of any phenomena, processes or systems of objects by constructing and studying their models. Essentially, this is one of the main categories of the theory of knowledge: any method is based on the idea of modeling scientific research- both theoretical and experimental. The experimental and simulation results are subject to careful analysis.

Analysis called a method of scientific research by decomposing an object into its component parts or mentally dismembering an object through logical abstraction. Analysis is inextricably linked with synthesis.

Synthesis is a method of studying a subject in its integrity, in the unity and interconnection of its parts. As a result of analysis and synthesis, the most successful research hypothesis becomes a working hypothesis, and if it is able to withstand attempts to refute it and still successfully predicts previously unexplained facts and relationships, then it can become theory.

Under theory understand a form of scientific knowledge that gives a holistic idea of the patterns and essential connections of reality. General direction scientific research is to achieve higher levels of predictability. If no facts can change a theory, and the deviations from it that occur are regular and predictable, then it can be elevated to the rank of law- a necessary, essential, stable, repeating relationship between phenomena in nature. As the body of knowledge increases and research methods improve, hypotheses and even firmly established theories can be challenged, modified, and even rejected because they themselves scientific knowledge are dynamic in nature and constantly subject to critical rethinking.

The historical method reveals the patterns of the appearance and development of organisms, the formation of their structure and function. In some cases, using this method new life acquire hypotheses and theories that were previously considered false. This, for example, happened with Darwin's assumptions about the nature of signal transmission in a plant in response to environmental influences. The comparative-descriptive method involves conducting an anatomical and morphological analysis of the objects of study. It underlies the classification of organisms, identifying patterns of occurrence and development various forms life.

Monitoring is a system of measures for observing, assessing and forecasting changes in the state of the object under study, in particular the biosphere. Carrying out observations and experiments often requires the use of special equipment such as microscopes, centrifuges, spectrophotometers, etc. Microscopy is widely used in zoology, botany, human anatomy, histology, cytology, genetics, embryology, paleontology, ecology and other branches of biology. It allows you to study thin structure objects using light, electron, X-ray and other types of microscopes.

A light microscope consists of optical and mechanical parts. Optical parts are involved in constructing the image, and mechanical parts serve for ease of use of the optical parts. The overall magnification of a microscope is determined by the formula: objective magnification x eyepiece magnification = microscope magnification.
For example, if the lens magnifies the object by 8 times and the eyepiece by 7, then overall increase microscope is 56.

Differential centrifugation, or fractionation, allows particles to be separated according to their size and density under the influence of centrifugal force, which is actively used in studying the structure of biological molecules and cells.

Basic levels of organization of living nature

Molecular genetic. The most important tasks Biology at this stage is the study of the mechanisms of transmission of genetic information, heredity and variability.
Cellular level. Elementary unit cellular level organization is the cell, and the elementary phenomenon is the reactions of cellular metabolism.
Tissue level. This level is represented by tissues that combine cells of a certain structure, size, location and similar functions. Tissues arose during historical development along with multicellularity. In multicellular organisms, they are formed during ontogenesis as a consequence of cell differentiation.
Organ level. The organ level is represented by the organs of organisms. In protozoa, digestion, respiration, circulation of substances, excretion, movement and reproduction are carried out due to various organelles. More advanced organisms have organ systems. In plants and animals, organs are formed due to different quantities fabrics.
Organismic level. Elementary unit this level is an individual in its individual development, or ontogenesis, therefore organismal level also called ontogenetic. An elementary phenomenon at this level is changes in the body in its individual development.
Population-species level. A population is a collection of individuals of the same species, freely interbreeding with each other and living separately from other similar groups of individuals. In populations there is a free exchange of hereditary information and its transmission to descendants. The population is elementary unit population-species level, but an elementary phenomenon in in this case are evolutionary transformations, such as mutations and natural selection.
Biogeocenotic level. Biogeocenosis is a historically established community of populations different types, interconnected with each other and the environment by metabolism and energy. Biogeocenoses are elementary systems, in which the matter-energy cycle occurs due to the vital activity of organisms. Biogeocenoses themselves are elementary units of a given level, while elementary phenomena are flows of energy and cycles of substances in them. Biogeocenoses make up the biosphere and determine all the processes occurring in it.
Biosphere level. The biosphere is the shell of the Earth inhabited by living organisms and transformed by them. The biosphere is the most high level organization of life on the planet. This shell covers the lower part of the atmosphere, the hydrosphere and upper layer lithosphere. The biosphere, like all others biological systems, dynamic and actively transformed by living beings. It itself is an elementary unit of the biosphere level, and the processes of circulation of substances and energy that occur with the participation of living organisms are considered as an elementary phenomenon.

As mentioned above, each of the levels of organization of living matter makes its contribution to a single evolutionary process: in the cell, not only the inherent hereditary information, but it also changes, which leads to the emergence of new combinations of signs and properties of the organism, which in turn are subject to the action natural selection at the population-species level, etc.