>> Research methods in biology

1. How does science differ from religion and art?
2. What is the main goal of science?
3. What research methods are used in biology, You know?

Science as a sphere of human activity.

Science is one of the spheres of human activity, the purpose of which is the study and knowledge of the surrounding world. Scientific knowledge requires the selection of certain objects of research, problems and methods for studying them.

Experiment- a research method in biology in which the experimenter deliberately changes conditions and observes how they affect living organisms. The experiment can be carried out both in the laboratory and outdoors.

In practical microbiology it is used for the diagnosis of infectious diseases, isolation and identification of pure pathogens, indication and identification of exotoxins. In addition, it is widely used in experimental microbiology and immunology, as well as for monitoring immunodrugs.

The experimental method is highly sensitive. In cases of isolation of pure grass and the establishment of immunological changes in an animal, the experimental method is highly specific and can be used in the early stages of the disease. The disadvantages of the experimental method are labor intensity, high cost, duration of the study, and the danger of laboratory contamination. Therefore, it is used in cases where other methods are ineffective and if the necessary conditions for keeping laboratory animals are available.

The use of the experimental method in biology is associated with the name of William Harvey, who used it in his research to study blood circulation. But it began to be widely used in biology only from the beginning of the 19th century, primarily in the study of physiological processes. The experimental method allows you to study a particular phenomenon of life through experience. A great contribution to the establishment of the experimental method in biology was made by G. Mendel, who, while studying the heredity and variability of organisms, was the first to use experiment not only to obtain data about the phenomena being studied, but also to test the hypothesis formulated on the basis of the results obtained. G. Mendel's work has become a classic example of the methodology of experimental science.

In the 20th century the experimental method became leading in biology. This became possible thanks to the emergence of new instruments for biological research (electron microscope, tomograph, etc.) and the use of methods of physics and chemistry in biology.

Currently, in biological experiments, various types of microscopy are widely used, including electronic microscopy with the technique of ultrathin sections, biochemical methods, various methods of cultivating and intravital observation of cell cultures, tissues and organs, the method of labeled atoms, X-ray diffraction analysis, ultracentrifugation, chromatography, etc. . It is no coincidence that in the second half of the 20th century. A whole direction has developed in biology - the creation of new instruments and the development of research methods.

In biological research, modeling is increasingly being used, which is considered the highest form of experiment. Thus, active work is underway on computer modeling of the most important biological processes, the main directions of evolution, the development of ecosystems, or even the entire biosphere (for example, in the case of global climate or man-made changes).

The experimental method, combined with a systems-structural approach, radically transformed biology, expanded its cognitive capabilities and opened new ways for the use of biological knowledge in all spheres of human activity.

The process of scientific knowledge is usually divided into two stages: empirical and theoretical.

At the empirical stage The following methods are used.

Descriptive and comparative methods , they are based on observation. Observation - study of living nature objects in natural conditions. This is direct observation (literally) of the behavior, settlement, reproduction of animals and plants in nature, visual or instrumental determination of the characteristics of organisms, their cells, organs and tissues. For these purposes, modern biology uses both traditional means of field research - from binoculars to deep-sea submersibles, and complex laboratory equipment - microscopes, spectrophotometers, ultracentrifuges, etc.

Experimental method based on study of living objects under extreme influence of environmental factors- changed temperature, light or humidity, increased load, toxicity or radioactivity, change in the place of development (removal or transplantation of genes, cells, organs, space flights, etc.). The experimental method allows us to identify hidden properties, the limits of the adaptive capabilities of living systems, the degree of their flexibility, reliability, and variability.

Historical method reveals the history of the development of biological objects, their origin. Compare the anatomical structure, chemical composition, gene structure and other characteristics of organisms of different levels of complexity. In this case, not only living organisms are studied, but also long-extinct ones preserved in the form of fossilized remains.

A relatively new method - modeling biological processes , both at the level of organisms, cells or biomolecules, and And math modeling. For example, you can build a model and forecast the state of life in a reservoir after a certain time when one, two or more parameters change (temperature, salt concentration, presence of predators, etc.).

System method (approach) is also new . Living objects are considered as systems , that is, a collection of elements with certain relationships. Each object is considered simultaneously both as a system and as an element of a higher order system.

On theoretical stage the following methods are used for cognition: generalization accumulated facts , promotion new hypotheses , their empirical re-test (new observations, experiments, comparisons, modeling). Confirmed hypotheses become laws , they are made up of theories . It is clear that both laws and theories are relative in nature and can sooner or later be revised.

3. Basic concepts of biology

Concept - this is an interconnected group of concepts, hypotheses, theories that explain some fundamental phenomenon or property of nature. Basicbiological concepts explain the phenomenon and propertieslife .

1. The concept of a systemic multi-level organization of life : all living objects are systems different levels of complexity, they form a continuous hierarchy of levels of structural and functional organization.

2. Concept of material essence of life : life is material, its physical and chemical basis is the metabolism and energy. In a philosophical sense, this means the primacy of matter and the secondary nature of consciousness (materialism).

Matter is a combination of matter and field. Matter has rest mass, but the field does not. Living matter representsparticularly complex substance and a complex multifactorial field. Exactlydifficulty level makes matter alive, although simple physical and chemical laws operate within it.

3. Concept of biological information and self-reproduction of life : Living organisms reproduce based on their own (genetic) information in interaction with external (epigenetic) information. The result of this interaction is the individual development of organisms (ontogenesis).

4. The concept of self-regulation of living systems : living systems maintain the relative constancy of their internal connections and operating conditions (homeostasis) based on a combination of direct positive and inverse negative connections.

5. Concept of self-organization and biological evolution : the living world arose as a result of self-organization from non-living chemical systems and undergoes irreversible historical development (phylogeny) based on hereditary variability and natural selection of organisms best adapted to changing environmental conditions.

When we talk about biology, we are talking about the science that deals with the study of all living things. All living beings, including their habitat, are studied. From the structure of cells to complex biological processes, all this is the subject of biology. Let's consider research methods in biology, which are currently in use.

Biological research methods include:

• · Empirical/Experimental Methods
• · Descriptive methods
• · Comparative methods
• · Statistical methods
• · Modeling
• · Historical methods

Empirical methods consist in the fact that the object of experience is subjected to a change in the conditions of its existence, and then the results obtained are taken into account. Experiments are of two types depending on where they are conducted: laboratory experiments and field experiments. Natural conditions are used to conduct field experiments, and special laboratory equipment is used to conduct laboratory experiments.

Descriptive methods are based on observation, followed by analysis and description of the phenomenon. This method allows us to highlight the features of biological phenomena and systems. This is one of the most ancient methods.

Comparative methods imply comparison of the obtained facts and phenomena with other facts and phenomena. Information is obtained through observation. Recently, it has become popular to use monitoring. Monitoring is constant observation, which allows you to collect data on the basis of which analysis and then forecasting will be carried out.

Statistical methods also known as mathematical methods, and are used to process numerical data that was obtained during an experiment. In addition, this method is used to ensure the reliability of certain data.

Historical methods are based on the study of previous facts, and allow us to determine existing patterns. But since one method is not always sufficiently effective, it is customary to combine these methods to obtain better results.

Modeling This is a method that has been gaining momentum lately and involves working with objects by representing them in models. What cannot be analyzed and studied after an experiment can be learned through modeling. Partially, not only conventional modeling is used, but also mathematical modeling.

Let's look at analogy and modeling in biological research.

Analogy and modeling in biology

Analogy is understood as similarity, similarity of some properties, characteristics or relationships of generally different objects. Establishing similarities (or differences) between objects is carried out as a result of their comparison. Thus, comparison is the basis of the analogy method.

If a logical conclusion is made about the presence of any property, sign, relationship in the object under study based on establishing its similarity with other objects, then this conclusion is called an inference by analogy. The course of such an inference can be presented as follows. Let there be, for example, two objects A and B. It is known that object A has the properties P1 P 2,..., Pn, Pn+1. The study of object B showed that it has properties P 1 P 2,..., Pn, which coincide, respectively, with the properties of object A. Based on the similarity of a number of properties (P 1 P 2,..., Pn) for both objects it can be done assumption about the presence of property Рn+1 in object B.

The degree of probability of obtaining a correct conclusion by analogy will be the higher: 1) the more common properties of the compared objects are known; 2) the more significant the common properties discovered in them and 3) the more deeply the mutual natural connection of these similar properties is known. At the same time, it must be borne in mind that if an object in respect of which an inference is made by analogy with another object has some property that is incompatible with the property the existence of which should be concluded, then the general similarity of these objects loses all meaning .

These considerations about inference by analogy can also be supplemented with the following rules:

1) common properties must be any properties of the objects being compared, i.e., selected “without prejudice” against properties of any type; 2) property Pn+1 must be of the same type as the general properties P 1 P 2,..., Pn; 3) general properties P 1 P 2, ..., Pn should be as specific as possible for the objects being compared, i.e., belong to the smallest possible range of objects; 4) property Pn+1, on the contrary, should be the least specific, i.e., belong to the largest possible range of objects.

There are different types of inferences by analogy. But what they have in common is that in all cases one object is directly examined, and a conclusion is drawn about another object. Therefore, inference by analogy in the most general sense can be defined as the transfer of information from one object to another. In this case, the first object, which is actually subject to research, is called a model, and the other object, to which the information obtained as a result of studying the first object (model) is transferred, is called the original (sometimes a prototype, sample, etc.). Thus, the model always acts as an analogy, that is, the model and the object (original) displayed with its help are in a certain similarity (similarity).

“Modeling is understood as the study of a modeled object (original), based on the one-to-one correspondence of a certain part of the properties of the original and the object (model) that replaces it in the study and includes the construction of a model, its study and the transfer of the obtained information to the modeled object - the original”

Models in biology are used to simulate biological structures, functions and processes at different levels of organization of living things: molecular, subcellular, cellular, organ-systemic, organismal and population-biocenotic. It is also possible to model various biological phenomena, as well as the living conditions of individuals, populations and ecosystems.

In biology, mainly three types of models are used: biological, physicochemical and mathematical (logical-mathematical). Biological models reproduce in laboratory animals certain conditions or diseases found in humans or animals. This allows us to study experimentally the mechanisms of occurrence of a given condition or disease, its course and outcome, and influence its course. Examples of such models are artificially induced genetic disorders, infectious processes, intoxication, reproduction of hypertensive and hypoxic conditions, malignant neoplasms, hyperfunction or hypofunction of certain organs, as well as neuroses and emotional states. To create a biological model, various methods are used to influence the genetic apparatus, infection with microbes, introduction of toxins, removal of individual organs or introduction of their waste products (for example, hormones), various effects on the central and peripheral nervous system, exclusion of certain substances from food, placement into an artificially created habitat and many other ways. Biological models are widely used in genetics, physiology, and pharmacology.

Physicochemical models reproduce biological structures, functions or processes by physical or chemical means and, as a rule, are a distant resemblance to the biological phenomenon being modeled. Since the 60s. 19th century Attempts were made to create a physicochemical model of the structure and some functions of cells. Thus, the German scientist M. Traube (1867) imitated the growth of a living cell by growing CuSO 4 crystals in an aqueous solution of K 4: the French physicist S. Leduc (1907), immersing fused CaCl2 in a saturated solution of K 3PO 4, obtained - thanks to the action of surface forces tension and osmosis - structures that externally resemble algae and mushrooms. By mixing olive oil with various water-soluble substances and placing this mixture in a drop of water, O. Büchli (1892) obtained microscopic foams that had an external resemblance to protoplasm; such a model even reproduced amoeboid movement. Since the 60s 19th century Various physical models of the conduction of excitation along the nerve have also been proposed. In the model created by the Italian scientist C. Matteucci and the German scientist L. Hermann, the nerve was presented in the form of a wire surrounded by a sheath of a conductor of the second kind. When the sheath and wire were connected to the galvanometer, a potential difference was observed, which changed when electrical “irritation” was applied to the “nerve” area. This model reproduced some bioelectric phenomena during nerve stimulation. The French scientist R. Lilly, using a model of excitation waves propagating along a nerve, reproduced a number of phenomena observed in nerve fibers (refractory period, “all or nothing” law, bilateral conduction). The model was a steel wire, which was placed first in strong and then in weak nitric acid. The wire was coated with oxide, which was reduced under a number of influences; The restoration process that arose in one section spread along the wire. Such models, which have shown the possibility of reproducing certain properties and manifestations of living things through physical and chemical phenomena, are based on external qualitative similarity and are of only historical interest.

Later, more complex models, based on much deeper quantitative similarities, were built on the principles of electrical and electronic engineering. Thus, based on data from electrophysiological studies, electronic circuits were built that simulate bioelectric potentials in a nerve cell, its process and synapse. Mechanical machines with electronic control have also been built that simulate complex acts of behavior (the formation of a conditioned reflex, processes of central inhibition, etc.).

Significantly greater progress has been achieved in modeling the physicochemical conditions of existence of living organisms or their organs and cells. Thus, solutions of inorganic and organic substances have been selected (solutions of Ringer, Locke, Tyrode, etc.), simulating the internal environment of the body and supporting the existence of isolated organs or cells cultured outside the body.

Models of biological membranes (a film of natural phospholipids separates an electrolyte solution) make it possible to study the physicochemical basis of ion transport processes and the influence of various factors on it. With the help of chemical reactions occurring in solutions in a self-oscillatory mode, oscillatory processes characteristic of many biological phenomena are modeled - differentiation, morphogenesis, phenomena in complex neural networks, etc.

Mathematical models (mathematical and logical-mathematical descriptions of the structure, connections and patterns of functioning of living systems) are built on the basis of experimental data or speculatively, formally describe a hypothesis, theory or open pattern of a biological phenomenon and require further experimental verification. Various versions of such experiments reveal the limits of application of the mathematical model and provide material for its further adjustment. In some cases, a mathematical model makes it possible to predict certain phenomena that were previously unknown to the researcher. Thus, the model of cardiac activity proposed by the Dutch scientists van der Pol and van der Mark, based on the theory of relaxation oscillations, indicated the possibility of a special disturbance of the heart rhythm, subsequently discovered in humans. Among the mathematical models of physiological phenomena, one should also mention the model of nerve fiber excitation developed by the English scientists A. Hodgkin and A. Huxley. Based on the theory of nerve networks by American scientists W. McCulloch and W. Pits, logical and mathematical models of the interaction of neurons are built. Systems of differential and integral equations form the basis for modeling biocenoses (V. Volterra, A.N. Kolmogorov). The Markov mathematical model of the evolution process was built by O.S. Kulagina and A.A. Lyapunov. THEM. Gelfand and M.L. Tsetlin, based on game theory and the theory of finite automata, developed model ideas about the organization of complex forms of behavior. In particular, it has been shown that the control of numerous muscles of the body is based on the development of certain functional blocks in the nervous system - synergies, and not through independent control of each muscle. The creation and use of mathematical and logical-mathematical methods and their improvement contribute to the further development of mathematical and theoretical biology.

The modeling method in biology is a means of establishing increasingly deeper and more complex relationships between biological theory and experience. In the last century, the experimental method in biology began to encounter certain limits, and it became clear that a number of studies are impossible without modeling. If we look at some examples of limitations in the scope of the experiment, they will mainly be as follows: (19 from 15)

• - experiments can only be carried out on currently existing objects (impossibility of extending the experiment to the area of ​​the past);
• - interference in biological systems is sometimes of such a nature that it is impossible to establish the causes of the changes that occur (due to the intervention or for other reasons);
• - some theoretically possible experiments are not feasible due to the low level of development of experimental technology;
• - a large group of experiments related to human experimentation should be rejected for moral and ethical reasons.

But modeling is widely used in the field of biology not only because it can replace experiment. It has great independent significance, which is expressed, according to a number of authors (19, 20,21), in a number of advantages:

• 1. Using the modeling method on one set of data, you can develop a number of different models, interpret the phenomenon under study in different ways, and select the most fruitful of them for theoretical interpretation;
• 2. In the process of building a model, you can make various additions to the hypothesis under study and obtain its simplification;
• 3. In the case of complex mathematical models, a computer can be used;
• 4. The possibility of conducting model experiments opens up (synthesis of amino acids according to Miller) (19 p. 152).

All this clearly shows that modeling performs independent functions in biology and is becoming an increasingly necessary step in the process of creating a theory. However, modeling retains its heuristic value only when the limits of application of any model are taken into account.

Stages of conducting biological research

Currently, the modeling method (French) is widely used in various branches of biological science. modele- “sample”, “prototype”), when the characteristics of the object being studied are reproduced on a specially created model. In this case, there must be a certain similarity between the model and the object of interest to the researcher. Modeling is widely used if the object of study is very complex (multicomponent) or difficult to directly observe. In these cases, modeling helps not only to identify the properties and interdependencies of the object being studied, but also to present its characteristics under changing conditions.

Stages and methods of biological research.

Biological research is the main method of analysis used in the study of living matter.

Living matter has several levels of organization. All of them are described in biology. Each level can be studied through biological research, the most important of which are:

• comparative-descriptive;
• experimental;
• monitoring method;
• modeling method.

After conducting biological research according to this scheme, the result is processed using the method of mathematical and statistical analysis.

The very first method of analysis that began to be used was comparative descriptive. It made it possible to describe the shape of an organism or phenomenon. After this, when conducting biological research, a comparative analysis of the object or phenomenon with other forms or processes is carried out. This method can be used at all levels of organization of living matter from the atomic to the biocenotic.

The task of any scientific research is to classify all biological objects, identifying groups based on the degree of their similarity or differences.

Biological research is based on a number of principles:

• comparison is carried out only within one level of organization of living matter - atoms with atoms, alleles with alleles, etc.;
• determining whether the object under study belongs to one group or another (depending on the level of the organization);
• Only representatives of the same species can be compared.

The experimental method of biological research is an artificial change in any parameters that affect the living conditions of the objects of study, then analyzing the results of the experiment.

There are two types of experiments: field and laboratory.

1. The field experiment is carried out in the natural habitat of the research objects. The objects of field experiments are groups of organisms for which it is problematic to organize laboratory living conditions, since this significantly distorts its results;

2. laboratory experiments are carried out in artificially equipped premises - laboratories. It is most appropriate to conduct such experiments at the atomic, molecular, cellular, tissue or organismal levels. Sometimes, to conduct this type of biological research, artificial populations of organisms are created, individual living cells or clones are laboratory cultures created specifically for scientific experiments. This property has found application in industry in the form of biotechnology. This area is now actively developing, and its results are used both in the food and pharmaceutical industries for growing crops that produce medicinal substances.

The next type of biological research is monitoring, which is based on constant observation of processes occurring at individual levels of organization of living matter. This study allows us to determine the state of the research objects and make a probable forecast of their changes, analyze the consequences that changes in any global parameters (for example, the climate of planet Earth) can lead to.

Based on the findings obtained, tactics are developed to be used in the event of this situation, and methods for preventing such situations. Monitoring can also use retrospective analysis of materials accumulated over a certain period. With their help, for example, it is possible to identify changes in habitats and establish a possible cause of this phenomenon. And also explore intraspecific ecological and geographic variability in this situation.

The modeling method is intervention in the natural processes of the habitat of the objects under study. It allows you to study processes that cannot be observed in the natural environment or reproduced in the laboratory.

Modeling can more reliably predict the consequences of various processes.

But we should not forget that when modeling, only a significantly simplified model is created, which cannot reflect the full complexity of objects or phenomena that occur with them. It has only general features of the probable development of events, which are described in biological research.

A subtype of modeling is the creation of a mathematical model - this is the expression of pairwise connections of the animal or plant world in the form of numbers. The creation of a mathematical model of biological research is preceded by the accumulation of accurate data about objects, phenomena and processes that occur with them. And the results are taken based on previously conducted experiments. Thus, the use of each method of biological research is logical; each method is a continuation of the previous one. In this case, the results of the previous stage of the study are used.

When using mathematical modeling, electronic computer technology is used, the level of development of which at this stage makes it possible to create highly complex mathematical models with many options for the development of events.

The statistical method of biological research is used to establish the reliability of the data obtained at each stage of biological research. Only after the final stage of the study, namely the statistical stage, can we say that this theory is scientifically substantiated.

Biological research is a scientific method of conducting research. It consists of several stages and can be applied at each level of organization of living matter. The results obtained after each subsequent level of research are used to organize the next level, resulting in a logical continuous research model. And only after going through all the stages of biological research, the results obtained can be called scientific.