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2 Ekaterina Timofeevna Zakharova Sergei Grigorievich Mamontov Vladimir Borisovich Zakharov Nikolai Ivanovich Sonin Biology. General biology. profile level. Grade 11 Text provided by the copyright holder Biology. General biology. profile level. Grade 11: textbook. for general education institutions/in. B. Zakharov, S. G. Mamontov, N. I. Sonin, E. T. Zakharova: Bustard; Moscow; 2013 ISBN Abstract The textbook introduces students to the most important laws of the living world. It gives an idea of ​​the evolution of the organic world, the relationship of the organism and the environment. The textbook is addressed to students of the 11th grade of educational institutions.

3 Contents Preface Section 1. The doctrine of the evolution of the organic world Chapter 1. Patterns of the development of living nature. Evolutionary doctrine 1.1. The history of ideas about the development of life on Earth Ancient and medieval ideas about the essence and development of life The system of organic nature K. Linnaeus Development of evolutionary ideas. The evolutionary theory of J.-B. Lamarck 1.2. Prerequisites for the emergence of the theory of Ch. Darwin Natural science prerequisites for the theory of Ch. Darwin Expeditionary material of Ch. Darwin 1.3. Ch. Darwin's evolutionary theory Ch. Darwin's doctrine of artificial selection Ch. Darwin's doctrine of natural selection 1.4. Modern ideas about the mechanisms and patterns of evolution. Microevolution View. Criteria and structure Evolutionary role of mutations Genetic stability of populations Genetic processes in populations Forms of natural selection Adaptation of organisms to environmental conditions as a result of natural selection End of the introductory fragment

4 V. B. Zakharov, S. G. Mamontov, N. I. Sonin, E. T. Zakharova Biology. General biology. profile level. 11 grade 4

5 Foreword Dear friends! We continue to study the basics of general biological knowledge, which we started in the 10th grade. The objects of our attention will be the stages of the historical development of living nature, the evolution of life on Earth and the formation and development of ecological systems. To study these important issues in full, you will need the knowledge acquired last year, since the laws of heredity and variability lie at the heart of development processes. Particular attention in the textbook is given to the analysis of relationships between organisms and the conditions for the sustainability of ecological systems. The educational material of a number of sections has been significantly expanded due to the presentation of general biological patterns as the most difficult to understand. Other sections provide only basic information and concepts. The range of issues that you will meet in grade 11 is very wide, but not all of them are covered in detail in the textbook. For a more detailed acquaintance with certain issues of biology, a list of additional literature is given at the end of the textbook. In addition, not all regularities are known or fully understood, because the complexity and diversity of life are so great that we are only beginning to understand some of its phenomena, while others are still waiting to be studied. The educational material in the book is structured in the same way as in the textbook “General Biology. Grade 10” (V. B. Zakharov, S. G. Mamontov, N. I. Sonin). The authors are grateful to M. T. Grigorieva for preparing the text in English, as well as to Yu. Academician of the Russian Academy of Natural Sciences, Professor V. B. Zakharov 5

6 Section 1. The doctrine of the evolution of the organic world The world of living organisms has a number of common features that have always caused a feeling of amazement in a person. First, this is the extraordinary complexity of the structure of organisms; secondly, the obvious purposefulness, or adaptive nature, of many signs; as well as a huge variety of life forms. The questions raised by these phenomena are quite obvious. How did complex organisms arise? Under the influence of what forces their adaptive features were formed? What is the origin of the diversity of the organic world and how is it maintained? What place does man occupy in the organic world and who are his ancestors? In all ages, mankind has tried to find answers to these and many other similar questions. In pre-scientific societies, explanations resulted in legends and myths, some of which served as the basis for various religious teachings. The scientific interpretation is embodied in the theory of evolution, which is the subject of this section. The evolution of the living world is understood as a natural process of the historical development of living nature from the very beginning of life on our planet to the present. The essence of this process is both in the continuous adaptation of living things to constantly changing environmental conditions, and in the emergence of more and more complex forms of living organisms. In the course of biological evolution, pre6

7 formation of species, on this basis new species arise; the disappearance of species is also constantly happening, their extinction. 7

8 Chapter 1. Patterns of development of living nature. Evolutionary teaching Everything is and is not, because although there will come a moment when it is, but here it ceases to be One and the same and young and old, and dead and alive, then it changes into this, this, changing, becomes again topics. Heraclitus The main work of Charles Darwin "The Origin of Species", which radically changed the idea of ​​wildlife, appeared in 1859. This event was preceded by more than twenty years of work on the study and understanding of the rich factual material collected by both Darwin himself and other scientists. In this chapter you will get acquainted with the basic premises of evolutionary ideas, the first evolutionary theory of J.-B. Lamarck; learn about Ch. Darwin's theory of artificial and natural selection; on modern ideas about the mechanisms and rate of speciation. Currently, more than 600 thousand plants and at least 2.5 million animal species, about 100 thousand species of fungi and more than 8 thousand prokaryotes, as well as up to 800 species of viruses have been described. Based on the ratio of the described and not yet identified modern species of living organisms, scientists make the assumption that the modern fauna and flora are represented by about 4.5 million species of organisms. In addition, using paleontological and some other data, the researchers calculated that during the entire history of the Earth, at least 1 billion species of living organisms lived on it. Let us consider how in different periods of human history people imagined the essence of life, the diversity of living things and the emergence of new forms of organisms History of ideas about the development of life on Earth AD), but long before him, the literary monuments of various peoples of antiquity contained a lot of interesting information about the organization of wildlife, mainly related to agronomy, animal husbandry and medicine. Biological knowledge itself is rooted in ancient times and is based on the direct practical activities of people. According to the rock paintings of the Cro-Magnon man (13 thousand years BC), it can be established that already at that time people could well distinguish a large number of animals that served as the object of their hunt. Antique and medieval ideas about the essence and development of life In ancient Greece in VIII VI centuries BC e. in the bowels of a holistic philosophy of nature, the first rudiments of ancient science arose. The founders of Greek philosophy Thales, Anaximander, Anaximenes and Heraclitus were looking for a material source from which the world arose due to natural self-development. For Thales, this first principle was water. Living beings, according to the teachings of Anaximander, are formed from the indefinite matter of "apeiron" according to the same laws as objects of inanimate nature. Ionian philosopher Anaximenes 8

9 considered the material principle of the world to be air, from which everything arises and into which everything returns. He also identified the human soul with air. The greatest of the ancient Greek philosophers was Heraclitus of Ephesus. His teaching did not contain special provisions about living nature, but it was of great importance both for the development of all natural science and for the formation of ideas about living matter. Heraclitus for the first time introduced into philosophy and the science of nature a clear idea of ​​constant change. The scientist considered fire to be the beginning of the world; he taught that all change is the result of struggle: "Everything arises through struggle and out of necessity." The development of ideas about wildlife was greatly influenced by the research and speculative concepts of other scientists of antiquity: Pythagoras, Empedocles, Democritus, Hippocrates and many others (see Chapter 2 of the textbook "General Biology. Grade 10"). In the ancient world, numerous information about wildlife was collected for that time. Aristotle was engaged in a systematic study of animals, describing more than 500 species of animals and arranging them in a certain order: from simply arranged to more and more complex. The sequence of bodies of nature outlined by Aristotle begins with inorganic bodies and goes through plants to attached animal sponges and ascidians, and then to mobile marine organisms. Aristotle and his students also studied the structure of plants. In all bodies of nature, Aristotle distinguished two sides: matter, which has various possibilities, and the form of the soul, under the influence of which this possibility of matter is realized. He distinguished three kinds of soul: the vegetative, or nourishing, inherent in plants and animals; sentient, characteristic of animals, and the mind, which, in addition to the first two, is endowed only with man. Throughout the Middle Ages, the works of Aristotle were the basis of ideas about wildlife. With the establishment of the Christian Church in Europe, an official point of view based on biblical texts spreads: all living things are created by God and remain unchanged. This direction in the development of the biology of the Middle Ages is called creationism (from the Latin creatio creation, creation). A characteristic feature of this period is the description of existing species of plants and animals, attempts to classify them, which for the most part were purely formal (in alphabetical order) or applied. Many systems of classifications of animals and plants have been created, in which individual characters are arbitrarily taken as the basis. Interest in biology increased in the era of the Great Geographical Discoveries (XV century) and the development of commodity production. Intensive trade and the discovery of new lands expanded information about animals and plants. New plants such as cinnamon, cloves, potatoes, corn, and tobacco were brought to Europe from India and America. Botanists and zoologists described many new previously unseen plants and animals. For practical purposes, they indicated what beneficial or harmful properties these organisms possess. System of organic nature by K. Linnaeus The need to streamline rapidly accumulating knowledge led to the need to systematize them. Practical systems are being created in which plants and animals are combined into groups depending on their benefit to humans or the harm they bring. For example, isolated medicinal plants, horticultural or horticultural crops. The concepts of "livestock" or "poisonous animals" served to refer to the most diverse animals in their structure and origin. Due to convenience, the practical classification of species is still used today. nine

10 However, classification of living organisms on the basis of usefulness could not satisfy scientists. They were looking for properties that would allow plants and animals to be grouped according to similarities in structure and life. Initially, one or a small number of arbitrarily chosen features were taken as the basis of taxonomy. It is clear that completely unrelated organisms fell into the same group. During the 16th and 17th centuries work continued on the description of animals and plants, their systematization. A great contribution to the creation of a system of nature was made by the outstanding Swedish naturalist Carl Linnaeus. The scientist described more than 8,000 plant species and over 4,000 animal species, established a uniform terminology and order for describing species. He grouped similar species into genera, similar genera into orders, and orders into classes. Thus, he based his classification on the principle of hierarchy (i.e., subordination) of taxa (from the Greek taxis location, order; this is a systematic unit of one rank or another). In the Linnaean system, the largest taxon was the class, the smallest species, variety. This was an extremely important step towards the establishment of a natural system. Linnaeus consolidated the use of binary (i.e., double) nomenclature in science to designate species. Since then, each species has been called in two words: the first word means the genus and is common to all the species included in it, the second word is the specific name itself. With the development of science, some additional categories were introduced into the system: family, subclass, etc., and the type became the highest taxon. But the principle of building the system remained unchanged. For example, the systematic position of a domestic cat can be described as follows. The domestic cat (Libyan) is included in the genus of small cats of the cat family of the carnivorous order of the mammalian subtype of the vertebrate subtype of the chordate type. Along with the domestic cat, the genus of small cats includes the European wild forest cat, the Amur forest cat, the jungle cat, the lynx, and some others. Linnaeus created the most perfect system of the organic world for that time, including in it all the then known animals and all known plants. Being a great scientist, in many cases he correctly combined the types of organisms according to the similarity of structure. However, the arbitrariness in the choice of features for classification (in plants, the structure of stamens and pistils; in animals, the structure of the beak in birds; the structure of teeth in mammals) led Linnaeus to a number of errors. Linnaeus was aware of the artificiality of his system and pointed out the need to develop a natural system of nature. He wrote: "An artificial system serves only until a natural one is found." However, what meant for the scientist of the XVIII century. concept of "natural system"? As is now known, the natural system reflects the origin of animals and plants and is based on their kinship and similarity in terms of the totality of essential structural features. During the reign of religious ideas, scientists believed that the types of organisms were created independently of each other by the Creator and are unchanged. “There are as many species,” said Linnaeus, as many different forms the Almighty created at the beginning of the world. Therefore, the search for the natural system of nature meant for biologists attempts to penetrate into the plan of creation, which was guided by God, creating all life on Earth. The perfection of the structure of species, the mutual correspondence of internal organs, adaptability to the conditions of existence were explained by the wisdom of the Creator. However, among the philosophers and naturalists of the XVII XIX centuries. Another system of ideas about the variability of organisms was also widespread, based on the views of some ancient scientists. This direction in the development of biology is called transformism (from Latin transformo I transform, I transform). Proponents of transformism were such prominent scientists as R. Hooke, J. La Mettrie, D. Diderot, J. Buffon, Erasmus 10

11 Darwin, J. W. Goethe and many others. Transformers admitted the possibility of the expediency of the reactions of organisms to changes in external conditions, but did not prove the evolutionary transformations of organisms. A scientific interpretation of the origin of organic expediency was given only by Charles Darwin Development of evolutionary ideas. The evolutionary theory of J.-B. Lamarck Despite the dominance of views on the immutability of living nature, biologists continued to accumulate factual material that contradicted these ideas. The discovery of the microscope in the 17th century and its application in biological research greatly expanded the horizons of scientists. Embryology took shape as a science, paleontology arose. The scientist who created the first evolutionary theory was the outstanding French naturalist Jean-Baptiste Lamarck. Unlike many of its predecessors, Lamarck's theory of evolution was based on facts. The idea of ​​the inconsistency of species arose from a scientist as a result of a deep study of the structure of plants and animals. Through his work, Lamarck made a great contribution to biology. The very term "biology" was introduced by him. Being engaged in the taxonomy of animals, Lamarck drew attention to the similarity of essential structural features in animals that do not belong to the same species. On the basis of similarity, Lamarck singled out 10 classes of invertebrates instead of Linnaeus's two classes (Insects and Worms). Among them, such groups as "Crustaceans", "Arachnids", "Insects" have survived to this day, other groups "Mollusks", "Annneled worms" have been elevated to the rank of type. The well-known imperfection of Lamarck's systematics is explained by the level of science of that time, but there is a main desire in it to avoid the artificiality of groupings. We can say that Lamarck laid the foundations of the natural system of classification. He was the first to raise the question of the causes of similarities and differences in animals. “Could I consider a number of animals from the most perfect of them to the most imperfect,” wrote Lamarck, and not try to establish on what this so remarkable fact may depend? Should I not have supposed that nature created various bodies in succession, ascending from the simplest to the most complex? Let's pay attention to the words "nature created". For the first time since the time of Lucretius, the scientist dares to say that it was not God who created organisms of varying degrees of complexity, but nature on the basis of natural laws. Lamarck comes up with the idea of ​​evolution. His greatest merit lies in the fact that his evolutionary idea is carefully developed, supported by numerous facts and therefore turns into a theory. It is based on the idea of ​​development, gradual and slow, from simple to complex, and on the role of the external environment in the transformation of organisms. In his main work "Philosophy of Zoology", published in 1809, Lamarck provides numerous proofs of the variability of species. Among such evidence, Lamarck refers to changes under the influence of the domestication of animals and the cultivation of plants during the migration of organisms to other habitats with different conditions of existence. Lamarck assigns an important role in the emergence of new species to gradual changes in the hydrogeological regime on the Earth's surface and climatic conditions. Thus, in the analysis of biological phenomena, Lamarck includes two new factors, the factor of time and environmental conditions. This was a big step forward from the mechanistic ideas of the proponents of immutability of species. However, what are the mechanisms of variability of organisms and the formation of new species? eleven

12 Lamarck believed that there were two of them: firstly, the desire of organisms to improve and, secondly, the direct influence of the external environment and the inheritance of traits acquired during the life of the organism. Lamarck's views on the mechanism of evolution turned out to be erroneous. Ways of adaptation of living organisms to the environment and speciation 50 years later were discovered by Charles Darwin. The great merit of Lamarck lies in the fact that he created the first theory of the evolution of the organic world, introduced the principle of historicism as a condition for understanding biological phenomena, and put forward environmental conditions as the main reason for the variability of species. Lamarck's theory did not receive recognition from his contemporaries. In his time, science was not ready to accept the idea of ​​evolutionary transformation; the time frames that Lamarck spoke of, millions of years, seemed unimaginable. Evidence for the causes of species variation has not been strong enough. Assigning a decisive role in evolution to the direct influence of the external environment, the exercise and non-exercise of organs and the inheritance of acquired traits, Lamarck could not explain the emergence of adaptations due to "dead" structures. For example, the color of the shell of bird eggs is clearly adaptive in nature, but it is impossible to explain this fact from the standpoint of Lamarck's theory. Lamarck's theory proceeded from the concept of fused heredity, characteristic of the whole organism and each of its parts. The idea that heredity is a property of an organism as a whole was revived in the works of T. D. Lysenko. However, the discovery of the substance of DNA heredity and the genetic code eliminated the very point of contention. Lamarckism and neo-Lamarckism collapsed of their own accord. Thus, although the concept of the immutability of species was not shaken, it became more and more difficult for their supporters to explain the new and new facts discovered by biologists. In the first quarter of the XIX century. great advances were made in comparative anatomy and paleontology. Great merit in the development of these areas of biology belongs to the French scientist J. Cuvier. Investigating the structure of the organs of vertebrates, he found that all the organs of an animal are parts of one integral system. As a result, the structure of each organ naturally correlates with the structure of all others. No part of the body can change without a corresponding change in other parts. This means that each part of the body reflects the principles of the structure of the whole organism. So, if an animal has hooves, its entire organization reflects a herbivore lifestyle: the teeth are adapted to grinding coarse plant foods, the jaws have a certain shape, the stomach is multi-chambered, the intestines are very long, etc. e. If an animal's intestines serve to digest meat, other organs also have a corresponding structure: sharp teeth for tearing, jaws for capturing and holding prey, claws for grasping it, a flexible spine that promotes jumping, etc. Correspondence of the structure of animal organs Cuvier called each other the principle of correlations (relativity). Guided by the principle of correlations, Cuvier studied the bones of extinct species and restored the appearance and lifestyle of these animals. Paleontological data irrefutably testified to the change in the forms of animals on Earth. The facts came into conflict with the biblical legend. Initially, supporters of the immutability of living nature explained this contradiction very simply: those animals that Noah did not take into his ark during the Flood died out. Of such reasoning, Darwin later wrote with irony in his diary: "The theory according to which the mastodon, etc. died out because the door to Noah's ark was made too narrow." The unscientific nature of references to the biblical flood became apparent when the varying degrees of antiquity of extinct animals were established. Then Cuvier put forward the theory of catastrophes. According to this theory, the cause of extinction was periodically

13 outgoing major geological disasters that destroyed animals and vegetation in large areas. Then these territories were populated by species penetrating from neighboring regions. Followers and students of J. Cuvier, developing his teaching, argued that catastrophes covered the entire globe. Each catastrophe was followed by a new act of creation. They numbered 27 such catastrophes and, consequently, acts of creation. The theory of catastrophes has become widespread. However, there were scientists who doubted the theory, which, according to Engels, "in place of one act of divine creation, put a whole series of repeated acts of creation and made an essential lever of nature out of a miracle." These scientists included the Russian biologists K. F. Rulye and N. A. Severtsov. The ecological studies of K. F. Rul'e and the study of the geographical variability of species by N. A. Severtsov led them to the idea of ​​the possibility of relationship between species and the origin of one species from another. The works of N. A. Severtsov were highly appreciated by Ch. Darwin. The disputes between the adherents of the immutability of species and spontaneous evolutionists were put to an end by the deeply thought-out and fundamentally substantiated theory of speciation created by Charles Darwin. Summary Up to the beginning of the 19th century mostly descriptive methods were used in biology. Later prominent achievements in the field of natural history have determined the need for theories, explaining processes that take place in nature. The first such attempt was accomplished in 1809 by J.-B. Lamarck, who created the theory of evolution of living organisms. The great merit of his studies is connected with the fact that he has suggested the historic principle as a basis for understanding of all the biological phenomena, and considered the changes in the environment as the main reason for specific variation. However, his ideas on the process of evolution turned to be erroneous. Mechanisms of adaptations to the environment in living organisms, as well as the species formation were clarified by Charles Darwin only 50 years later. Reference points 1. In ancient times, there were spontaneous materialistic ideas about living nature. 2. In the Middle Ages, ideas about the creation of the world by the Creator and the immutability of living nature were dominant. 3. Lamarck considered a separate organism as an evolutionary unit. 4. Lamarck considered all living nature as a continuous series of gradations changing from simple to complex forms. 5. Advances in paleontology have made a significant contribution to the development of evolutionary ideas. Review questions and assignments 1. What is a practical classification system for living organisms? 2. What contribution did K. Linnaeus make to biology? 3. Why is the Linnaean system called artificial? 4. State the main provisions of Lamarck's evolutionary theory. 5. What questions have not been answered in Lamarck's evolutionary theory? 6. What is the essence of the principle of correlations of J. Cuvier? Give examples. 13

14 7. What is the difference between transformism and evolutionary theory? Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of "Reference points". Terminology For each term indicated in the left column, select the corresponding definition given in the right column in Russian and English. Select the correct definition for every term in the left column from English and Russian variants listed in the right column. Discussion Questions What was known about wildlife in the ancient world? How can one explain the dominance of ideas about the immutability of species in the 18th century? How did Cuvier explain the paleontological data on the change of forms of animals on Earth? Explain Cuvier's theory of catastrophes. What contribution to biology did J.-B. Lamarck? fourteen

15 1.2. Prerequisites for the emergence of Charles Darwin's theory To fully appreciate the full significance of the revolution in biological science committed by Charles Darwin, let's pay attention to the state of science and the socio-economic conditions of the first half of the 19th century, when the theory of natural selection was created. was a period of discovery of the fundamental laws of the universe. By the middle of the century, many major discoveries had been made in natural science. The French scientist P. Laplace mathematically substantiated I. Kant's theory of the development of the solar system (see Chapter 2 of the textbook "General Biology. Grade 10"). The idea of ​​development is introduced into philosophy by G. Hegel. A. I. Herzen in his “Letters on the Study of Nature”, published in the years, outlined the idea of ​​the historical development of nature from inorganic bodies to man. He argued that in natural science only those based on the principle of historical development can be true generalizations. The laws of conservation of energy were discovered, the principle of the atomic structure of chemical elements was established. In 1861, A. M. Butlerov created a theory of the structure of organic compounds. A little time will pass and D. I. Mendeleev will publish (1869) his famous Periodic Table of Elements. Such was the scientific environment in which Charles Darwin worked. Consider the specific premises of his teachings. Geological background. The English geologist C. Lyell proved the inconsistency of Cuvier's ideas about sudden catastrophes that change the surface of the Earth, and substantiated the opposite point of view: the surface of the planet changes continuously and not under the influence of any special forces, but under the influence of ordinary everyday factors of temperature fluctuations, wind, rain, surf and vital activity of plant and animal organisms. Among the constantly acting natural factors, Lyell attributed earthquakes, volcanic eruptions. Similar thoughts long before Lyell were expressed by M. V. Lomonosov in his work “On the Layers of the Earth” and Lamarck. But Lyell supported his views with numerous and rigorous proofs. Lyell's theory had a great influence on the formation of Charles Darwin's worldview. Achievements in the field of cytology and embryology. In biology, a number of major discoveries were made that turned out to be incompatible with the ideas of the immutability of nature, the absence of relationship between species. The cell theory of T. Schwann showed that the structure of all living organisms is based on a uniform structural element of the cell. Studies of the development of vertebrate embryos made it possible to detect gill arches and gill circulation in bird and mammal embryos, which suggested the idea of ​​the relationship of fish, birds, mammals and the origin of terrestrial vertebrates from ancestors leading an aquatic lifestyle. The Russian academician K. Baer showed that the development of all organisms begins with the egg and that in the early stages of development a striking similarity is found in the structure of the embryos of animals belonging to different classes. The type theory developed by J. Cuvier played an important role in the development of biology. Although J. Cuvier was a staunch supporter of the immutability of species, the similarity of the structure of animals established by him within the limits of the type objectively indicated their possible relationship and origin from the same root. 15

16 So, in various fields of natural science (geology, paleontology, biogeography, embryology, comparative anatomy, the study of the cellular structure of organisms), the materials collected by scientists contradicted the ideas of the divine origin and immutability of nature. The great English scientist C. Darwin was able to correctly explain all these facts, generalize them, and create a theory of evolution. C. Darwin's expeditionary material Let's trace the main stages of the life path, the formation of Darwin's worldview and his system of evidence. Charles Robert Darwin was born on February 12, 1809 in the family of a doctor. At the university, he studied first at the medical, then at the theological faculty and was going to become a priest. At the same time, he showed a great inclination towards the natural sciences, was fond of geology, botany and zoology. After graduating from university (1831), Darwin was offered a position as a naturalist on the ship Beagle, which was setting off on a round-the-world trip for cartographic surveys. Darwin accepts the invitation, and the five years he spent on the expedition () became a turning point in his own scientific destiny and in the history of biology. Fig Skeletons of sloths in South America (modern view on the right, fossil on the left) During the trip, observations made with great precision and skill led Darwin to ponder the reasons for the similarities and differences between the species. His main find, discovered in the geological deposits of South America, is the skeletons of extinct giant edentulous, very similar to modern armadillos and lazy 16

17 tsami (Fig. 1.1). Darwin was even more impressed by the study of the species composition of animals in the Galapagos Islands. On these volcanic islands of recent origin, Darwin discovered close species of finches, similar to the mainland species, but adapted to different food sources - hard seeds, insects, nectar of plant flowers (Fig. 1.2). It would be absurd to assume that for each newly emerging volcanic island, the Creator creates its own special species of animals. It is more reasonable to draw a different conclusion: the birds came to the island from the mainland and changed as a result of adaptation to new living conditions. Thus, Darwin raises the question of the role of environmental conditions in speciation. Darwin observed a similar picture off the coast of Africa. Animals living on the Cape Verde Islands, despite some similarities with mainland species, still differ from them in essential features. From the point of view of the creation of species, Darwin could not explain the features of the development of the tuko-tuko rodent he described, living in holes underground and giving birth to sighted cubs, which then go blind. Rice Variety of Darwin's finches in the Galapagos Islands and about. Coconut (depending on the nature of the food) These and many other facts shook Darwin's belief in the creation of species. Returning to England, he set himself the task of resolving the question of the origin of species. Reference points 1. The rapid development of the natural sciences in the 19th century. provided an increasing number of facts that contradicted ideas about the immutability of nature. 2. The study of the nature of South America and the Galapagos Islands allowed Darwin to make the first assumptions about the mechanisms of species change. Review questions and assignments 1. What data of geology served as a prerequisite for Darwin's evolutionary theory? 2. Describe the natural science prerequisites for the formation of Ch. Darwin's evolutionary views. 3. What observations of Charles Darwin shook his faith in the immutability of species? Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of "Reference points". 17

18 1.3. The evolutionary theory of Charles Darwin The main work of Charles Darwin "The Origin of Species by Means of Natural Selection, or the Preservation of Selected Breeds in the Struggle for Life", which radically changed the idea of ​​wildlife, appeared in 1859. This event was preceded by more than twenty years of work on the study and comprehension of the rich factual material collected by both Charles Darwin himself and other scientists Charles Darwin's doctrine of artificial selection Darwin returned to England from a round-the-world trip as a convinced supporter of the variability of species under the influence of habitat conditions. The data of geology, paleontology, embryology and other sciences also pointed to the variability of the organic world. However, most scientists did not recognize evolution: no one observed the transformation of one species into another. Therefore, Darwin concentrated his efforts on discovering the mechanism of the evolutionary process. To this end, he turned to the practice of agriculture in England. By this time, 150 breeds of pigeons, many breeds of dogs, cattle, chickens, etc. had been bred in this country. Work was intensively carried out on the selection of new breeds of animals and varieties of cultivated plants. Supporters of the permanence of species argued that each variety, each breed has a special wild ancestor. Darwin proved that this was not the case. All breeds of chickens are descended from wild Banking chickens, domestic ducks from wild mallard ducks, rabbit breeds from wild European rabbits. The ancestors of cattle were two types of wild aurochs, and dogs were the wolf and, for some breeds, possibly the jackal. At the same time, animal breeds and plant varieties can differ very sharply. Consider Figure 1.3. It shows some breeds of the domestic pigeon. They have unequal body proportions, sizes, plumage, etc., although they all come from the same ancestor of the wild rock pigeon. The head appendages of roosters are extremely diverse (Fig. 1.4), and they are typical for each breed. A similar picture is observed among varieties of cultivated plants. Very different among themselves, for example, varieties of cabbage. From one wild species, a person obtained cabbage, cauliflower, kohlrabi, fodder cabbage, the stem of which exceeds the height of a person, etc. (see the figure in the textbook "General Biology. Grade 10"). Varieties of plants and breeds of animals serve to satisfy human material or aesthetic needs. This alone convincingly proves that they are man-made. How did a person get numerous varieties of plants and animal breeds, what patterns does he rely on in his work? Darwin found the answer to this question by studying the methods of English farmers. Their methods were based on one principle: when breeding animals or plants, they looked for specimens among individuals that carried the desired trait in the most striking expression, and left only such organisms for reproduction. If, for example, the task is to increase the yield of wheat, the breeder selects from a huge mass of plants a few of the best specimens with the largest number of spikelets. The following year, the grains of only these plants are sown, and among them again organisms are found that have the largest number of spikelets. This continues for several years, and as a result, a new variety of multi-eared wheat appears. eighteen

19 Rice Domestic pigeon breeds: 1 messenger, 2 wild pigeon, 3 Jacobin, 4 owl pigeon, 5 puffin, 6 tumbler, 7 trumpet pigeon, 8 curly pigeon traits in organisms, and the selection by man of such changes that deviate most in the direction he desires. In a number of generations, such changes accumulate and become a stable feature of the breed or variety. For selection, only individual, indeterminate (hereditary) variability matters. Since mutations are rare, artificial selection can only be successful if it is carried out among a large number of individuals. There are also cases when a single major mutation leads to the emergence of a new breed. This is how the Ancona breed of short-legged sheep, dachshund, duck with a hooked beak, and some varieties of plants appeared. Individuals with dramatically changed traits were saved and used to create a new breed. Consequently, artificial selection is understood as the process of creating new breeds of animals and varieties of cultivated plants through the systematic conservation and reproduction of individuals with certain traits and properties that are valuable to humans in a number of generations. Darwin identified two forms of artificial selection, conscious or methodical, and unconscious. methodological selection. Conscious selection lies in the fact that the breeder sets himself a specific task and selects according to one or two traits. This approach allows you to achieve great success. Darwin gives an example of the rapid breeding of new breeds. When the task was set to turn the hanging crest of the Spanish 19

20 roosters in a standing one, then after five years the intended form was obtained. Chickens with "beards" were bred after six years. The possibilities of artificial selection in changing and transforming the structure and properties are extremely high. For example, a semi-wild cow yields l of milk per year, and individual individuals of modern dairy breeds up to l. In Merino, the number of hairs per unit area is almost 10 times greater than in outbred sheep. There are very great differences in the structure of the body in various breeds of dogs - greyhound, bulldog, St. Bernard, poodle or spitz. Fig. Head appendages in roosters of various breeds Conditions for the success of methodical artificial selection a large initial number of individuals. Such a selection is impossible with small-scale (peasant) agricultural production. A new breed cannot be bred if the farm has 1 2 horses or several sheep. Thus, the study of the selection methods used in large-scale capitalist agriculture in England in the 19th century allowed Darwin to formulate the principle of artificial selection and use this principle to explain not only the reason for the improvement of forms, but also their diversity. twenty

21 However, domestic animals, so different from their wild ancestors, date back to prehistoric man, long before the conscious use of selective breeding. How did it happen? According to Darwin, in the process of taming wild animals, man carried out a primitive form of artificial selection, which he called the unconscious. unconscious selection. Such selection is called unconscious in the sense that a person did not set a goal to breed any particular breed or variety. For example, the worst animals were killed and eaten first, while the most valuable ones were preserved (a more milky cow, a well-laid chicken, etc.). Darwin cites the example of the inhabitants of Tierra del Fuego, who eat dogs during the famine, cats that catch otters worse, and try to keep the best dogs at all costs. Unconscious selection still exists in the peasant economy, but its influence on the increase in the diversity of domestic animals and cultivated plants manifests itself much more slowly. C. Darwin did not have the opportunity to give examples of the domestication of wild animals through artificial selection carried out experimentally. There are such examples today. The Russian scientist academician D.K. Belyaev, working with silver-black foxes bred in captivity (canine family), discovered an interesting phenomenon. Animals differed greatly in their behavior and in their reaction to humans. D.K. Belyaev identified three groups among them: aggressive, seeking to attack a person, cowardly-aggressive, afraid of a person and at the same time wanting to attack him, and relatively calm with a pronounced exploratory instinct. Among this latter group, the scientist conducted a selection according to behavioral reactions: he left calmer animals for breeding, in which interest in the environment prevailed over the reaction of fear and protection. As a result of selection in a number of generations, it was possible to obtain individuals that behaved like domestic dogs: they easily made contact with humans, enjoyed affection, etc. , the tail was bent in a hook (like Siberian huskies), an asterisk appeared on the forehead, so characteristic of domestic (non-purebred) dogs. If wild foxes breed once a year, then domesticated ones twice. Some other features have also changed. In the described example, a relationship is found between changes in the structure and behavior of animals. Darwin noticed such a relationship and called it correlative, or correlative, variability. For example, the development of horns in sheep and goats is combined with the length of the coat. Polled animals have short hair. Dogs of hairless breeds usually have deviations in the structure of the teeth. The development of the crest on the head of chickens and geese is combined with a change in the skull. In cats, fur pigmentation is associated with the functioning of the senses: white, blue-eyed cats are always deaf. Correlative variability is based on the pleiotropic (multiple) action of genes. Reference points 1. Ch. Darwin singled out two main forms of artificial selection: methodical and unconscious. 2. Achievements of agriculture in England in the XIX century. in the field of breeding numerous breeds of domestic animals and plant varieties served for C. Darwin as a model of processes occurring in nature. 3. Large-scale agricultural production in England is considered as a socio-economic prerequisite for the theory of Charles Darwin. 21

22 Review and assignment questions 1. How did Charles Darwin solve the question about the ancestors of domestic animals? 2. Give examples of the variety of breeds of domestic animals and varieties of cultivated plants. What explains this diversity? 3. What is the main method of breeding new varieties and breeds? 4. How does the structure and behavior of animals change in the process of domestication? Give examples. Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of the "Reference points" Ch. Darwin's doctrine of natural selection Artificial selection, that is, the preservation of individuals with traits useful for reproduction and the elimination of all others, is carried out by a person setting itself certain tasks. Traits accumulated by artificial selection are beneficial to humans, but not necessarily beneficial to animals. Darwin suggested that in nature, signs that are useful only for organisms and the species as a whole accumulate in a similar way, as a result of which species and varieties are formed. In this case, it was required to establish the presence of uncertain individual variability in wild animals and plants. In addition, it was necessary to prove the existence in nature of some kind of directing factor that acts similarly to the will of man in the process of artificial selection. General individual variability and excess offspring. Darwin showed that in representatives of wild species of animals and plants, individual variability is very widely represented. Individual deviations can be beneficial, neutral or harmful to the organism. Do all individuals leave offspring? If not, what factors keep individuals with useful traits and eliminate all others? Darwin turned to the analysis of the reproduction of organisms. All organisms leave significant, sometimes very numerous offspring. One individual of herring spawns on average about 40 thousand eggs, sturgeon 2 million, frogs up to 10 thousand eggs. Up to a thousand seeds ripen annually on one poppy plant. Even slowly breeding animals have the potential to leave a huge number of offspring. Elephant females give birth to babies between the ages of 30 and 90. For 60 years, they give birth to an average of 6 elephants. Calculations show that even with such a low breeding rate, after 750 years, the offspring of one pair of elephants would be 19 million individuals. Based on these and many other examples, Darwin concludes that in nature any kind of animal and plant tends to reproduce exponentially. At the same time, the number of adults of each species remains relatively constant. Each pair of organisms produces many more offspring than they survive to adulthood. Most of the organisms that are born, therefore, die before reaching sexual maturity. The causes of death are varied: lack of food due to competition with representatives of their own species, attack by enemies, the action of unfavorable physical environmental factors of drought, severe frosts, high temperatures, etc. This implies the second conclusion made by Darwin: in nature there is a continuous struggle for existence. This term should be understood in a broad sense, as any dependence of organisms on the whole complex of conditions of the living nature surrounding it. In other words, the struggle for existence is a set of diverse and complex relationships that exist between organisms and environmental conditions. When the lion takes the prey from the hyena, 22

24 the genetic structure of the species is built, thanks to reproduction, new characters are widely distributed, a new species appears. Consequently, species change in the process of adaptation to environmental conditions. The driving force behind species change, i.e. evolution, is natural selection. The material for selection is hereditary (indefinite, individual, mutational) variability. Variability due to the direct influence of the external environment on organisms (group, modification) does not matter for evolution, since it is not inherited. Formation of new species. Darwin imagined the emergence of new species as a long process of accumulation of useful individual changes, increasing from generation to generation. Why is this happening? Life resources (food, breeding grounds, etc.) are always limited. Therefore, the most fierce struggle for existence takes place between the most similar individuals. On the contrary, there are fewer identical needs between individuals differing within the same species, and competition is weaker. Therefore, dissimilar individuals have an advantage in leaving offspring. With each generation, the differences become more pronounced, and intermediate forms that are similar to each other die out. So from one species two or more are formed. The phenomenon of divergence of characters, leading to speciation, Darwin called divergence (from the Latin divergo I deviate, I depart). Darwin illustrates the concept of divergence with examples found in nature. Competition between four-legged predators has led to the fact that some of them switched to feeding on carrion, others moved to new habitats, some of them even changed their habitat and began to live in water or on trees, etc. Divergence can also be caused by unequal external conditions. environment in different regions of the territory occupied by the species. For example, two groups of individuals of a species will therefore accumulate different changes. There is a process of divergence of signs. After a certain number of generations, such groups become varieties, and then species. The action of natural selection can be observed in the experiment. In our country, the common praying mantis is a large predatory insect (the body length in females reaches mm), feeding on a variety of small insects, aphids, bugs, and flies. The color of different individuals of this species is green, yellow and brown. Green praying mantises are found among grass and shrubs, brown on plants that burn out from the sun. The non-randomness of such a distribution of animals was proved by scientists in an experiment on a faded-brown area cleared of grass. Praying mantises of all three colors were tied to the pegs on the platform. During the experiment, birds destroyed 60% of yellow, 55% of green and only 20% of brown praying mantises, in which the body color coincided with the background color. Similar experiments were carried out with pupae of the hive butterfly. If the color of the pupa did not match the color of the background, the birds destroyed much more pupae than if the background matched the color. Waterfowl in the pool mainly catch fish, the color of which does not match the color of the bottom. It is important to note that it is not a single trait that matters for survival, but a complex of traits. In the same experiment with praying mantises, which is very simple compared to real natural conditions, among brown individuals protected by body color, birds pecked at restless, actively moving insects. Calm, sedentary praying mantises avoided the attack. One and the same sign, depending on the surrounding conditions, can contribute to survival or, on the contrary, attract the attention of enemies. Figure 1.5 shows two forms of the birch moth butterfly. The light form is hardly noticeable on light trunks and trees covered with lichens, while the mutant form is dark24

25 the painted form is clearly visible on them (A). Dark butterflies are predominantly pecked by birds. The situation changes near industrial enterprises: soot covering tree trunks creates a protective background for mutants, while a light butterfly is clearly visible (B). Mutations and the sexual process create genetic heterogeneity within a species. Their action, as can be seen from the above examples, is non-directional. Evolution, on the other hand, is a directed process, associated with the development of adaptations as the structure and functions of animals and plants progressively become more complex. There is only one directed evolutionary factor natural selection. Individuals or entire groups can be subject to selection. In any case, selection preserves the organisms most adapted to a given environment. Quite often, selection retains traits and properties that are unfavorable for an individual, but useful for a group of individuals or the species as a whole. An example of such a device is the serrated sting of a bee. A stinging bee leaves a sting in the body of the enemy and dies, but the death of an individual contributes to the preservation of the bee colony. Figure Forms of the moth moth The factors of selection are the conditions of the external environment, more precisely, the whole complex of abiotic and biotic environmental conditions. Depending on these conditions, selection acts in different directions and leads to unequal evolutionary results. Currently, there are several forms of natural selection, of which only the main ones will be considered below. Darwin showed that the principle of natural selection explains the emergence of all, without exception, the main characteristics of the organic world: from signs characteristic of large systematic groups of living organisms to small adaptations. Darwin's theory ended a long search by natural scientists who tried to find an explanation for many of the similarities observed in organisms belonging to different species. Darwin explained this similarity by kinship and showed how the formation of new species proceeds, how evolution occurs. From a general theoretical point of view, the main thing in Darwin's teaching is the idea of ​​the development of living nature, which opposes the idea of ​​a frozen, unchanging world. The recognition of Darwin's teachings was a turning point in the history of the biological sciences. The facts accumulated in the pre-Darwinian period of the development of biology received a new light. New trends in biology emerged: evolutionary embryology, evolutionary paleontology, etc. 25

26 Darwin's doctrine serves as a natural scientific basis for understanding the biological mechanisms of the development of life on Earth. The materialistic explanation of the expediency of the structure of living organisms, the origin and diversity of species is generally accepted in science. Darwin's work was one of the greatest achievements of natural science in the 19th century. Reference points 1. Individuals of any species are characterized by universal individual (hereditary) variability. 2. The number of offspring within each species of organisms is very large, and food resources are always limited. Review questions and assignments 1. What is natural selection? 2. What is the struggle for existence? What are its forms? 3. What form of struggle for existence is the most intense and why? Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of "Reference points". Discussion Questions Recall the material from previous chapters. What processes occurring in nature reduce the intensity of the intraspecific struggle for existence? What is the biological meaning of this phenomenon? What, in your opinion, are the biological reasons for the preservation of the life of individuals eliminated from reproduction? 1.4. Modern ideas about the mechanisms and patterns of evolution. Microevolution Ch. Darwin's evolutionary theory is based on the idea of ​​a species. What is a species and how real is its existence in nature? View. Criteria and structure A species is a set of individuals that are similar in structure, have a common origin, freely interbreed with each other and give fertile offspring. All individuals of the same species have the same karyotype, similar behavior, and occupy a certain area (distribution area). One of the important characteristics of a species is its reproductive isolation, that is, the existence of mechanisms that prevent the influx of genes from outside. The protection of the gene pool of a given species from the influx of genes from other species, including closely related ones, is achieved in different ways. The timing of reproduction in closely related species may not coincide. If the dates are the same, then the breeding sites do not match. For example, females of one species of frogs spawn along the banks of rivers, the other species in puddles. In this case, accidental insemination of eggs by males of another species is excluded. Many animal species have a strict mating ritual. If one of the potential partners for crossing the ritual of behavior deviates from the species, mating does not occur. If mating does occur, the spermatozoa of the male of the other species will not be able to penetrate the egg, and the eggs will not be fertilized26

27 rush. The preferred food sources also serve as an isolation factor: individuals feed in different biotopes, and the probability of interbreeding between them decreases. But sometimes (with interspecific crossing) fertilization does occur. In this case, the resulting hybrids are either characterized by reduced viability, or are infertile and do not produce offspring. A famous example of a mule is a hybrid of a horse and a donkey. Being quite viable, the mule is infertile due to a violation of meiosis: non-homologous chromosomes do not conjugate. The listed mechanisms that prevent the exchange of genes between species are not equally effective, but in combination under natural conditions they create an impenetrable genetic isolation between species. Consequently, the species is a real, genetically indivisible unit of the organic world. Each species occupies a more or less extensive range (from Latin area area, space). Sometimes it is relatively small: for species living in Baikal, it is limited to this lake. In other cases, the range of the species covers vast territories. Thus, the black crow is almost ubiquitous in Western Europe. Eastern Europe and Western Siberia are inhabited by another species of gray crow. The existence of certain boundaries of the distribution of a species does not mean that all individuals move freely within the range. The degree of mobility of individuals is expressed by the distance over which the animal can move, i.e., by the radius of individual activity. In plants, this radius is determined by the distance over which pollen, seeds, or vegetative parts can spread, capable of giving rise to a new plant. For a grape snail, the radius of activity is several tens of meters, for a reindeer it is more than a hundred kilometers, for a muskrat it is several hundred meters. Due to the limited radius of activity, forest voles living in one forest have little chance of meeting during the breeding season with forest voles inhabiting a neighboring forest. Common frogs spawning in one lake are isolated from the frogs of another lake, located a few kilometers from the first. In both cases, isolation is not complete because individual voles and frogs may migrate from one habitat to another. Individuals of any species are unevenly distributed within the species range. Areas of territory with a relatively high population density alternate with areas where the abundance of a species is low or there are no individuals of this species at all. Therefore, a species is considered as a collection of individual groups of populations of organisms. A population is a set of individuals of a given species occupying a certain area of ​​the territory within the range of the species, freely interbreeding with each other and partially or completely isolated from other populations. In reality, the species exists in the form of populations. The gene pool of a species is represented by gene pools of populations. The population is the elementary unit of evolution. Reference points 1. A species is a real-life elementary unit of living nature. 2. The basis for the existence of a species as a genetic unit of living nature is its reproductive isolation. 3. The vast majority of species of living organisms consists of individual populations. 4. The population, according to modern concepts, is an elementary evolutionary unit. Questions for review and assignments 1. Define the species. 27

28 2. Describe what biological mechanisms prevent the exchange of genes between species. 3. What is the reason for the infertility of interspecific hybrids? 4. What is the species range? 5. What is the radius of individual activity of organisms? Give examples of individual activity radius for plants and animals. 6. What is a population? Give a definition. Using the vocabulary of the sections "Terminology" and "Summary", translate into English the paragraphs of the "Reference Points" The evolutionary role of mutations Through the study of genetic processes in a population of living organisms, evolutionary theory has been further developed. A great contribution to population genetics was made by the Russian scientist S. S. Chetverikov. He drew attention to the saturation of natural populations with recessive mutations, as well as fluctuations in the frequency of genes in populations depending on the action of environmental factors, and substantiated the position that these two phenomena are the key to understanding evolutionary processes. Indeed, the mutation process is a constantly acting source of hereditary variability. Genes mutate at a certain frequency. It is estimated that on average one gamete out of 100 thousand 1 million gametes carries a newly emerged mutation at a particular locus. Since many genes mutate simultaneously, % of gametes carry one or another mutant allele. Therefore, natural populations are saturated with a wide variety of mutations. Due to combinative variability, mutations can be widely distributed in populations. Most organisms are heterozygous for many genes. It could be assumed that as a result of sexual reproduction, homozygous organisms will constantly be bred among the offspring, and the proportion of heterozygotes should steadily fall. However, this does not happen. The fact is that in the vast majority of cases, heterozygous organisms are better adapted to the conditions of existence than homozygous ones. Let's go back to the example of the birch moth butterfly. It would seem that light-colored butterflies, homozygous for the recessive allele (aa), living in a forest with dark tree trunks, should be quickly destroyed by enemies, and dark-colored butterflies homozygous for the dominant allele (AA) should become the only form under these living conditions. But for a long time in the smoky forests of southern England, light-colored moth butterflies are constantly found. It turned out that caterpillars homozygous for the dominant allele do not digest birch leaves covered with soot and soot, while heterozygous caterpillars grow much better on this food. Therefore, the greater biochemical flexibility of heterozygous organisms leads to their better survival, and selection acts in favor of heterozygotes. Thus, although most mutations under these specific conditions are harmful, and in the homozygous state, mutations tend to reduce the viability of individuals, they persist in populations due to selection in favor of heterozygotes. To understand evolutionary transformations, it is important to remember that mutations that are harmful in one environment may increase viability in other environmental conditions. In addition to the above examples, the following can be pointed out. A mutation that causes the underdevelopment or complete absence of wings in insects is certainly harmful under normal conditions, and is wingless.

29 Lying individuals are quickly replaced by normal ones. But on oceanic islands and mountain passes, where strong winds blow, such insects have an advantage over individuals with normally developed wings. Thus, the mutation process is the source of the reserve of hereditary variability of populations. By maintaining a high degree of genetic diversity in populations, it provides the basis for natural selection to operate. Reference points 1. In real-life populations, the mutation process continuously proceeds, leading to the emergence of new variants of genes and, accordingly, traits. 2. Mutations are a constant source of hereditary variability. Questions for repetition and tasks 1. What population-genetic patterns did the Russian biologist S. S. Chetverikov reveal? 2. What is the frequency of mutation of one specific gene in the natural conditions of the existence of individuals? Using the vocabulary of the "Terminology" and "Summary" rubrics, translate into English the paragraphs of the "Reference points" Genetic stability of populations Analyzing the processes occurring in a freely interbreeding population, the English scientist K. Pearson in 1904 established the existence of patterns that describe its genetic structure . This generalization, called the law of stabilizing crossing (Pearson's law), can be formulated as follows: under conditions of free crossing, for any initial ratio of the number of homozygous and heterozygous parental forms, as a result of the first crossing, a state of equilibrium is established within the population if the initial allele frequencies are the same for both floors. Consequently, whatever the genotypic structure of the population, that is, regardless of the initial state, already in the first generation obtained from free crossing, a state of population equilibrium is established, described by a simple mathematical formula. This law, important for population genetics, was formulated in 1908 independently by the mathematician G. Hardy in England and the physician W. Weinberg in Germany. According to this law, the frequency of homozygous and heterozygous organisms under conditions of free crossing in the absence of selection pressure and other factors (mutations, migration, gene drift, etc.) remains constant, i.e., is in a state of equilibrium. In its simplest form, the law is described by the formula: p2aa + 2pqAa + q2aa \u003d I, where p is the frequency of occurrence of gene A, q is the frequency of occurrence of allele a in percent. It should be noted that the Hardy-Weinberg law, like other genetic regularities based on the Mendelian principle of random combination, is mathematically exactly fulfilled with an infinitely large population. In practice, this means that populations with numbers below a certain minimum value do not satisfy the requirements of the Hardy-Weinberg law. 29

30 The Russian scientist S. S. Chetverikov gave an assessment of free crossing, indicating that it itself contains an apparatus that stabilizes the frequencies of genotypes in a given population. As a result of free crossing, there is a constant maintenance of the balance of genotypic frequencies in the population. The disturbance of equilibrium is usually associated with the action of external forces and is observed only as long as these forces exert influence. S. S. Chetverikov believed that a species, like a sponge, often absorbs mutations in a heterozygous state, while itself remaining phenotypically homogeneous. If the frequencies of genotypes in a population differ significantly from those calculated using the Hardy-Weinberg formula, it can be argued that this population is not in a state of population equilibrium and there are reasons preventing this. Let us dwell on them in more detail. Genetic processes in populations In different populations of the same species, the frequency of mutant genes is not the same. There are practically no two populations with exactly the same frequency of occurrence of mutant traits. These differences may be due to the fact that populations live in unequal environmental conditions. A directed change in the frequency of genes in populations is due to the action of natural selection. But even closely located, neighboring populations can differ from each other just as significantly as distantly located ones. This is explained by the fact that in populations a number of processes lead to an undirected random change in the frequency of genes, or, in other words, their genetic structure. For example, during the migration of animals or plants, an insignificant part of the original population settles in a new habitat. The gene pool of the newly formed population is inevitably less than the gene pool of the parent population, and the frequency of genes in it will differ significantly from the frequency of the genes of the original population. Genes, hitherto rare, are rapidly spreading among the members of a new population through sexual reproduction. At the same time, widespread genes may be absent if they were not in the genotype of the founders of the new population. Another example. Natural disasters - forest or steppe fires, floods, etc. - cause massive indiscriminate death of living organisms, especially inactive forms (plants, molluscs, reptiles, amphibians, etc.). Individuals that escaped death remain alive due to pure chance. In a population that has experienced a catastrophic decline in numbers, the allele frequencies will be different than in the original population. Following the decline in numbers, mass reproduction begins, the beginning of which is given by the remaining small group. The genetic composition of this group will determine the genetic structure of the entire population during its heyday. In this case, some mutations may completely disappear, while the concentration of others may accidentally rise sharply. In biocenoses, periodic fluctuations in the number of populations associated with relationships such as "predator-prey" are often observed. Increased reproduction of predators' prey objects on the basis of an increase in food resources leads, in turn, to increased reproduction of predators. The increase in the number of predators causes the mass destruction of their victims. The lack of food resources leads to a decrease in the number of predators (Fig. 1.6) and the restoration of the size of prey populations. These population fluctuations (“population waves”) change the frequency of genes in populations, which is their evolutionary significance. thirty

31 Fig. Fluctuations in the number of individuals in the population of predators and prey. Dashed line: A lynx, B wolf, C fox; solid line: mountain hare Changes in the frequency of genes in populations are also caused by the limitation of gene exchange between them due to spatial (geographical) isolation. Rivers serve as a barrier to terrestrial species, mountains and uplands isolate lowland populations. Each of the isolated populations has specific features associated with living conditions. An important consequence of isolation is closely related crossing (inbreeding). Due to inbreeding, recessive alleles, spreading in a population, appear in a homozygous state, which reduces the viability of organisms. In human populations, isolates with a high degree of inbreeding are found in mountainous areas, on islands. The isolation of certain groups of the population for caste, religious, racial and other reasons still retained its significance. The evolutionary significance of various forms of isolation is that it perpetuates and reinforces genetic differences between populations, and that the divided parts of a population or species are subjected to unequal selection pressures. Thus, changes in the frequency of genes caused by various environmental factors serve as the basis for the emergence of differences between populations and subsequently determine their transformation into new species. Therefore, changes in populations in the course of natural selection are called microevolution. Reference points 1. In nature, there are often sharp fluctuations in the number of individuals associated with mass indiscriminate death of organisms. 2. The genotypes of randomly preserved individuals determine the gene pool of a new population during its heyday. Review questions and assignments 1. Formulate the Hardy-Weinberg law. 2. What processes lead to a change in the frequency of occurrence of genes in populations? 3. Why do different populations of the same species differ in gene frequency? 4. What is microevolution? 31

33 phenotypes, i.e. the whole complex of features, and hence certain combinations of genes inherent in a given organism. Selection is often compared to the work of a sculptor. Just as a sculptor from a shapeless block of marble creates a work that strikes with the harmony of all its parts, so selection creates adaptations and species, eliminating less successful individuals from reproduction, or, in other words, less successful combinations of genes. Therefore, they talk about the creative role of natural selection, since the result of its action are new types of organisms, new forms of life. stabilizing selection. Another form of natural selection, stabilizing selection, operates under constant environmental conditions. The importance of this form of selection was pointed out by the outstanding Russian scientist I. I. Shmalgauzen. Stabilizing selection is aimed at maintaining a previously established average trait or property: the size of the body or its individual parts in animals, the size and shape of a flower in plants, the concentration of hormones or glucose in the blood in vertebrates, etc. Stabilizing selection preserves the fitness of the species, eliminating sharp deviations the severity of the sign from the average norm. So, in insect-pollinated plants, the size and shape of flowers are very stable. This is explained by the fact that the flowers must correspond to the structure and size of the body of pollinating insects. A bumblebee is not able to penetrate a too narrow corolla of a flower; the proboscis of a butterfly cannot touch too short stamens in plants with a very long corolla. In both cases, flowers that do not fully correspond to the structure of pollinators do not form seeds. Consequently, the genes that caused the deviation from the norm are eliminated from the gene pool of the species. The stabilizing form of natural selection protects the existing genotype from the destructive effect of the mutation process. Under relatively constant environmental conditions, individuals with an average severity of signs have the greatest adaptability, and sharp deviations from the average norm are eliminated. Thanks to stabilizing selection, “living fossils” have survived to this day: the coelacanth coelacanth fish, whose ancestors were widespread in the Paleozoic era; a representative of the ancient reptiles, the hatteria, which looks like a large lizard, but has not lost the structural features of the reptiles of the Mesozoic era; a relic cockroach that has changed little since the Carboniferous; the gymnosperm plant ginkgo, which gives an idea of ​​the ancient forms that became extinct in the Jurassic period of the Mesozoic era (Fig. 1.7). The North American opossum depicted in the same figure retains the appearance characteristic of animals that lived tens of millions of years ago. Rice Examples of relict forms: A tuatteria, B latimeria, C opossum, G ginkgo Sexual selection. Dioecious animals differ in the structure of the reproductive organs. However, the difference between the sexes often extends to external signs, behavior33

34 nii. One can recall a bright outfit of feathers from a rooster, a large comb, spurs on the legs, loud singing. Male pheasants are very beautiful compared to much more modest hens. The fangs of the upper jaws of the tusks grow especially strongly in male walruses. Numerous examples of external differences in the structure of the sexes are called sexual dimorphism and are due to their role in sexual selection. Sexual selection is the competition between males for the opportunity to reproduce. This goal is served by singing, demonstrative behavior, courtship. Often there are fights between males (Fig. 1.8). In birds, pairing during the breeding season is accompanied by mating games, or mating. Showing is expressed in the fact that the bird takes a characteristic position of the body, in special movements, in the deployment and swelling of the plumage, in the publication of peculiar sounds. For example, black grouse on currents gather several dozen in forest clearings at night. The peak of the current falls on the early morning. Violent fights arise between the males, while the females at this time sit on the edges of the clearing or in the bushes. As a result of sexual selection, the most active, healthy and strong males leave offspring, the rest are removed from reproduction and their genotypes disappear from the gene pool of the species. Fig Leking black grouse Fig Sexual dimorphism in the structure of primates: A male proboscis, B female proboscis 34

35 Sometimes a bright wedding dress appears in animals only for the breeding season. Male moor frogs acquire a beautiful bright blue color in the water. The bright coloration of males and their demonstrative behavior unmask them in front of predators and increase the likelihood of death. However, this is beneficial for the species as a whole, as the females remain safer during the breeding season. The connection between the discreet appearance of female birds and care for offspring is clearly seen in the example of the phalarope oystercatcher, an inhabitant of our northern latitudes. In these birds, only the male incubates the eggs. The female has a much brighter color. Sexual dimorphism and sexual selection are widespread in the animal kingdom quite widely up to primates (Fig. 1.9). This form of selection should be considered as a special case of intraspecific natural selection. Reference points 1. Natural selection is the only factor that directionally changes the frequency of genes in populations. 2. When the conditions of existence change, the driving form of natural selection causes divergence, which can later lead to the emergence of new species. Review questions and assignments 1. What are the forms of natural selection? 2. Under what environmental conditions does each form of natural selection operate? 3. What is the reason for the emergence of resistance to pesticides in microorganisms, agricultural pests and other organisms? 4. What is sexual selection? Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of "Reference points". Questions for discussion What do you think is the main driving force behind the beak-shaped divergence process in Darwin's finches? Can the same environmental factor in different habitats be the cause of driving and stabilizing selection? Explain your answer with examples Adaptation of organisms to environmental conditions as a result of natural selection Plant and animal species are surprisingly adapted to the environmental conditions in which they live. A huge number of the most diverse features of the structure are known, providing a high level of adaptability of the species to the environment. The concept of “fitness of a species” includes not only external signs, but also the correspondence of the structure of internal organs to the functions they perform, for example, the long and complex digestive tract of animals that eat plant foods (ruminants). Correspondence of the physiological functions of the organism to the living conditions, their complexity and diversity are also included in the concept of fitness. Adaptive features of the structure, body color and behavior of animals. In animals, body shape is adaptive. The shape of the water mammal is well known.

36 hoarding dolphins. His movements are light and precise. Independent speed in water reaches 40 km / h. Often, cases are described of how dolphins accompany high-speed sea vessels, for example, destroyers moving at a speed of 65 km / h. This is explained by the fact that dolphins attach themselves to the bow of the ship and use the hydrodynamic force of the waves that arise when the ship moves. But this is not their natural speed. The density of water is 800 times that of air. How does the dolphin manage to overcome it? In addition to other structural features, the ideal adaptability of the dolphin to the environment and lifestyle is facilitated by the shape of the body. The torpedo-shaped body shape avoids the formation of a swirl of water currents surrounding the dolphin. The streamlined shape of the body contributes to the rapid movement of animals in the air. Flight and contour feathers covering the bird's body completely smooth its shape. Birds do not have protruding auricles, in flight they usually retract their legs. As a result, birds are far superior in speed to all other animals. For example, a peregrine falcon dives on its prey at speeds up to 290 km/h. Birds move quickly even in water. A chinstrap penguin has been observed swimming underwater at about 35 km/h. Rice Thicket fish: 1 ragfish, 2 clown fish, 3 aluthers, 4 pipefish In animals that lead a secretive, hiding lifestyle, devices that make them look like objects of the environment are useful. The bizarre body shape of fish living in thickets of algae (Fig. 1.10) helps them successfully hide from enemies. Resemblance to objects of the environment is widespread in insects. Known beetles, their appearance resembling lichens; cicadas, similar to the thorns of the shrubs among which they live. Stick insects look like a small brown or green twig (Fig. 1.11), while Orthopteran insects mimic a leaf (Fig. 1.12). Flat body have fish leading a benthic lifestyle. Protective coloring also serves as a means of protection from enemies. Birds that incubate eggs on the ground merge with the surrounding background (Fig. 1.13). Inconspicuous and there are 36 of them

37 eggs with pigmented shells and the chicks hatching from them (Fig. 1.14). The protective nature of egg pigmentation is confirmed by the fact that in species whose eggs are inaccessible to enemies of large predators, or in birds that lay eggs on rocks or bury them in the ground, the protective color of the shell does not develop. Rice Stick insect is so similar to a twig that it is almost invisible Rice Insects, body shape similar to leaves Protective coloration is widespread among a wide variety of animals. Butterfly caterpillars are often green, the color of the leaves, or dark, the color of the bark or earth. Bottom fish are usually painted to match the color of the sandy bottom (stingrays and flounders). At the same time, flounders are still able to change color depending on the color of the surrounding background (Fig. 1.15). The ability to change color by redistributing the pigment in the integument of the body is also known in terrestrial animals (chameleon). Desert animals are usually yellow-brown or sandy-yellow in color. Monochromatic protective coloration is characteristic of both insects (locusts) and small lizards, as well as large ungulates (antelopes) and predators (lion). 37

38 Rice Eider on the nest If the environmental background does not remain constant depending on the season, many animals change color. For example, inhabitants of middle and high latitudes (arctic fox, hare, ermine, ptarmigan) are white in winter, which makes them invisible in the snow. However, often in animals there is a body color that does not hide, but, on the contrary, attracts attention, unmasks. This coloration is characteristic of poisonous, burning or stinging insects: bees, wasps, blister beetles. A ladybug, very noticeable, is never pecked by birds because of the poisonous secret secreted by insects. Inedible caterpillars, many poisonous snakes have a bright warning color. Bright coloring warns the predator in advance about the futility and danger of the attack. Through trial and error, predators quickly learn to avoid attacking prey with warning coloration. Rice Protective coloration of eggs and chicks of birds when breeding offspring on the ground 38

40 calcium left, accumulated in the thorns of some plants, protect them from being eaten by caterpillars, snails and even rodents. Formations in the form of a hard chitinous cover in arthropods (beetles, crabs), shells in mollusks, scales in crocodiles, shells in armadillos and turtles protect them well from many enemies. The quills of the hedgehog and porcupine serve the same. All these adaptations could have appeared only as a result of natural selection, i.e., the preferential survival of more protected individuals. Figure Similarity of egg coloration in different subspecies of the common cuckoo and bird hosts Adaptive behavior is of great importance for the survival of organisms in the struggle for existence. In addition to hiding or demonstrative, frightening behavior when an enemy approaches, there are many other options for adaptive behavior that ensures the survival of adults or juveniles. This includes storing food for the unfavorable season of the year. This is especially true for rodents. For example, the root vole, common in the taiga zone, collects grains of cereals, dry grass, roots up to 10 kg in total. Burrowing rodents (mole rats, etc.) accumulate pieces of oak roots, acorns, potatoes, steppe peas up to 14 kg. A large gerbil living in the deserts of Central Asia cuts grass at the beginning of summer and drags it into holes or leaves it on the surface in the form of piles. This food is used in the second half of summer, autumn and winter. The river beaver collects stumps of trees, branches, etc., which he puts into the water near his dwelling. These warehouses can reach a volume of 20 m3. Feed stocks are also made by predatory animals. Mink and some ferrets store frogs, snakes, small animals, etc. An example of adaptive behavior is the time of greatest activity. In the deserts, many animals come out to hunt at night when the heat subsides. Reference points 1. The whole organization of any kind of living organisms is adaptive to the conditions in which it lives. 2. Adaptations of organisms to the environment are manifested at all levels of organization: biochemical, cytological, histological and anatomical. 3. Physiological adaptations are an example of the reflection of the structural features of the organization in the given conditions of existence. Questions for repetition and tasks 1. Give examples of the adaptability of organisms to the conditions of existence. 40

41 2. Why do some animal species have a bright unmasking color? 3. What is the essence of the phenomenon of mimicry? 4. How is the low abundance of the imitator species maintained? 5. Does the action of natural selection extend to the behavior of animals? Give examples. Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of "Reference points". Rice A male of a perch-like species hatches eggs in its mouth 41

• ZÁKLADNÉ ÚDAJE oblasť podnikania výroba organokremičitých prípravkov Evolutionary doctrine Evolution is the irreversible historical development of living nature. A brief history of the development of biology in the pre-Darwinian period The main concept in biology in the pre-Darwinian period was creationism

  MOSCOW D R O f a 2007 V. B. ZAKHAROV, S. G. MAMONTOV, N. I. SONIN, E. T. ZAKHAROVA BIOLOGY PROFILE LEVEL CLASS TEXTBOOK FOR GENERAL EDUCATIONAL INSTITUTIONS Edited by Academician of the Russian Academy of Natural Sciences, Professor V.

  Explanatory note. The test task "Evidence of Evolution" is designed to consolidate the material in the lesson

The textbook introduces students to the most important laws of the living world. It gives an idea of ​​the evolution of the organic world, the relationship of the organism and the environment.
The textbook is addressed to students of the 11th grade of educational institutions.

Material is presented on the origin of life on Earth, the structure of the cell, reproduction and individual development of organisms, the basics of heredity and variability. In accordance with the achievements of science, the doctrine of the evolutionary development of the organic world is considered, and material on the basics of ecology is presented. In connection with the growing importance of modern breeding methods, biotechnology and environmental protection, the presentation of these issues has been expanded. Factual material on the consequences of anthropogenic pollution of the environment is given. Corresponds to the current Federal state educational standard of secondary vocational education of a new generation.
For students of educational institutions implementing programs of secondary vocational education.

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Life is represented by an extraordinary variety of forms, many types of living organisms. From the Diversity of Living Organisms course, you remember that about 350,000 plant species and about 2 million animal species are currently known to inhabit our planet. And that's not counting fungi and bacteria! In addition, scientists are constantly describing new species - both existing today and extinct in past geological epochs. Revealing and explaining the common properties and causes of the diversity of living organisms is the task of general biology and the purpose of this textbook. An important place among the problems considered by general biology is occupied by questions of the origin of life on Earth and the laws of its development, as well as the interconnection of various groups of living organisms among themselves and their interaction with the environment.

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The manual contains answers to questions to paragraphs of the textbook by V. B. Zakharov, S. G. Mamontov, N. I. Sonin “General biology. Grade 10".
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Material on the origin of life on Earth, cell structure, reproduction and individual development of organisms, the basics of heredity and variability is presented In accordance with the achievements of science, the doctrine of the evolutionary development of the organic world is considered, material is presented on the basics of ecology In connection with the increasing importance of modern methods of selection, biotechnology and environmental protection, the presentation of these issues has been expanded. Factual material is given on the consequences of anthropogenic pollution of the environment Corresponds to the current Federal State Educational Standard of Secondary Vocational Education of a New Generation For students of educational institutions implementing programs of secondary vocational education

GENERAL BIOLOGY.

Chapter. ORIGIN AND INITIAL STAGES OF DEVELOPMENT OF LIFE ON EARTH

Section II. TEACHING ABOUT THE CELL

Section III. REPRODUCTION AND INDIVIDUAL DEVELOPMENT OF ORGANISMS

Section IV. BASICS OF GENETICS AND SELECTION

Section V. THE DOCTRINE OF THE EVOLUTION OF THE ORGANIC WORLD

Section V. RELATIONSHIP OF THE ORGANISM AND THE ENVIRONMENT. BASICS OF ECOLOGY

Books and textbooks on the discipline Textbooks:

1. Kolesnikov S.I. General biology: textbook / S.I. Kolesnikov. - 5th ed., erased. - M.: KNORUS, 2015. - 288 p. - (Secondary vocational education) - 2015
2. Mamontov S.G. General biology textbook /S. G. Mamontov, V. B. Zakharov - 11th above, erased. - M.: KNORUS.2015. - 328 p. - (Secondary vocational education). - 2015
3. Yakubchik, T.N. Clinical gastroenterology: a manual for students of medical, pediatric, medical and psychological faculties, interns, clinical residents, gastroenterologists and therapists / T.N. Yakubchik. - 3rd ed., add. and reworked. - Grodno: GrGMU, 2014. - 324 p. - year 2014
4. Ovsyannikov V.G. General pathology: pathological physiology: textbook / V.G. Ovsyannikov; GBOU VPO RostGMU of the Ministry of Health of Russia. - 4th ed. - Rostov n / D .: Publishing House of Rostov State Medical University, 2014 - Part I. General pathophysiology - 2014
5. The team of authors. Introduction of new technologies in medical organizations. Foreign experience and Russian practice. 2013 - 2013
6. The team of authors. MODERN WAYS OF PROCESSING HANDS OF SURGEONS AND THE OPERATING FIELD / D. V. Balatsky, N. B. Davtanyan - Barnaul: publishing house "Concept" 2012 - 2012
7. Mamyrbaev A.A. Fundamentals of occupational medicine: study guide. 2010 - 2010
8. Ivanov D.D. Lectures on Nephrology. Diabetic kidney disease. hypertensive nephropathy. Chronic renal failure. - Donetsk: Publisher Zaslavsky A.Yu., 2010. - 200 s. - 2010
9. Baranov V.S. Genetic passport - the basis of individual and predictive medicine / Ed. V. S. Baranova. - St. Petersburg: Publishing house N-L, 2009. - 528 p.: ill. - year 2009
10. Nazarenko G.V. Coercive measures of a medical nature: textbook, manual / G.V. Nazarenko. - M.: Flinta: MPSI, 2008. - 144 p. - 2008
11. Mazurkevich G.S., Bagnenko S.F.
12. Schmidt I.R. Fundamentals of Applied Kinesiology. Lectures for listeners of cycles of general and thematic improvement. Novokuznetsk - 2004 - 2004

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V. B. Zakharov, S. G. Mamontov, N. I. Sonin, E. T. Zakharova
Biology. General biology. profile level. Grade 10

Foreword

Our time is characterized by an ever-increasing interdependence of people. A person's life, his health, working and living conditions depend almost entirely on the correctness of the decisions made by so many people. In turn, the activity of an individual also affects the fate of many. That is why it is very important that the science of life become an integral part of the worldview of every person, regardless of his specialty. A civil engineer, process engineer, reclamation engineer needs knowledge of biology just like a doctor or agronomist, because only in this case they will represent the consequences of their production activities for nature and man. Biological knowledge is also necessary for representatives of the humanities as an important part of the universal cultural heritage. Indeed, throughout the ages, disputes between philosophers and theologians, scientists and charlatans sang around knowledge of wildlife. Ideas about the essence of life served as the basis for many worldview concepts.

The purpose of the authors of this book is to give an idea of ​​the structure of living matter, its most general laws, to acquaint with the diversity of life and the history of its development on Earth. Particular attention is paid to the analysis of relationships between organisms and the conditions for the sustainability of ecological systems. A large place in a number of sections is given to the presentation of general biological laws as the most difficult to understand. In other sections, only the most necessary information and concepts are given.

There is a wide range of topics that you will get to know while reading this book. However, not all of them could be covered in sufficient detail. This is not accidental - the complexity and diversity of life are so great that we are only beginning to understand some of its phenomena, while others are still waiting to be studied. This book only touches upon the important issues of the organization of living systems, their functioning and development. For a more detailed acquaintance with certain issues of biology, a list of additional literature is given at the end of the textbook.

The educational material in the book consists of sections, including chapters; within most chapters, there are usually several paragraphs that deal with certain specific topics. A summary in English is provided at the end of the paragraph. As an additional educational material, the text of the manual includes small bilingual dictionaries that allow you to study biological terminology in Russian and English and repeat the material covered. The sections "Reference points" and "Questions for review" will allow you to once again pay attention to the most important provisions of the material covered. Using the vocabulary of the dictionary and the summary, you can easily translate the text of the Reference Points into English. The section "Questions for discussion" contains two or three questions, for the answer to which, in some cases, it is necessary to attract additional literature. They can be used for optional or in-depth study of the topic. For the same purpose, “Problem areas” and “Applied aspects” of the studied educational material are indicated at the end of each chapter.

Each chapter ends with a list of the main provisions necessary for memorization, as well as tasks for independent work based on the knowledge gained.

The authors express their gratitude to M. T. Grigorieva for preparing the English text, as well as to Yu.

Academician of the Russian Academy of Natural Sciences, Professor V. B. Zakharov

Introduction

Biology is the science of life. Its name comes from a combination of two Greek words: bios (life) and logos (word, teaching). Biology studies the structure, manifestations of life, the habitat of all living organisms: bacteria, fungi, plants, animals, humans.

Life on Earth is represented by an extraordinary variety of forms, many types of living beings. Currently, about 600 thousand plant species, more than 2.5 million animal species, a large number of fungal and prokaryotic species that inhabit our planet are already known. Scientists are constantly discovering and describing new species, both existing in modern conditions and extinct in past geological epochs.

The disclosure of the general properties of living organisms and the explanation of the reasons for their diversity, the identification of relationships between the structure and environmental conditions are among the main tasks of biology. An important place in this science is occupied by the questions of the origin and laws of the development of life on Earth - the evolutionary doctrine. Understanding these laws is the basis of the scientific worldview and is necessary for solving practical problems.

Biology is divided into separate sciences according to the subject of study.

Thus, microbiology studies the world of bacteria; botany explores the structure and life of representatives of the plant kingdom; zoology - the animal kingdom, etc. At the same time, areas of biology are developing that study the general properties of living organisms: genetics - patterns of inheritance of traits, biochemistry - ways of transforming organic molecules, ecology - the relationship of populations with the environment. Physiology studies the functions of living organisms.

In accordance with the level of organization of living matter, such scientific disciplines as molecular biology, cytology - the study of the cell, histology - the study of tissues, etc.

Biology uses a variety of methods. One of the most important is historical, which serves as the basis for understanding the facts obtained. The traditional method is the descriptive method; instrumental methods are widely used: microscopy (light-optical and electronic), electrography, radar, etc.

In the most diverse areas of biology, the importance of boundary disciplines that connect biology with other sciences - physics, chemistry, mathematics, cybernetics, etc. is increasing. This is how biophysics, biochemistry, and bionics arose.

The emergence of life and the functioning of living organisms are determined by natural laws. The knowledge of these laws allows not only to make an accurate picture of the world, but also to use them for practical purposes.

Recent achievements in biology have led to the emergence of fundamentally new directions in science, which have become independent sections in the complex of biological disciplines. Thus, the disclosure of the molecular structure of the structural units of heredity (genes) served as the basis for the creation of genetic engineering. With the help of its methods, organisms are created with new, including those not found in nature, combinations of hereditary traits and properties. The practical application of the achievements of modern biology already at the present time makes it possible to obtain industrially significant amounts of biologically active substances.

Based on the study of the relationship between organisms, biological methods have been created to combat pests of agricultural crops. Many adaptations of living organisms have served as models for the design of effective artificial structures and mechanisms. At the same time, ignorance or ignorance of the laws of biology leads to serious consequences for both nature and man. The time has come when the safety of the world around us depends on the behavior of each of us. To properly regulate the engine of a car, to prevent the discharge of toxic waste into the river, to provide bypass channels for fish in the project of a hydroelectric power plant, to resist the desire to collect a bouquet of wild flowers - all this will save the environment, the environment of our life.

The exceptional ability of living nature to restore has created the illusion of its invulnerability to the destructive effects of man, the boundlessness of its resources. Now we know that this is not the case. Therefore, all human economic activity should now be built taking into account the principles of the organization of the biosphere.

The importance of biology to humans is enormous. General biological laws are used in solving a variety of issues in many sectors of the national economy. Thanks to the knowledge of the laws of heredity and variability, great success has been achieved in agriculture in the creation of new highly productive breeds of domestic animals and varieties of cultivated plants. Scientists have bred hundreds of varieties of cereals, legumes, oilseeds and other crops that differ from their predecessors in high productivity and other useful qualities. Based on this knowledge, selection of microorganisms producing antibiotics is carried out.

Great importance in biology is attached to solving problems associated with elucidating the subtle mechanisms of protein biosynthesis, the secrets of photosynthesis, which will open the way for the synthesis of organic nutrients outside plant and animal organisms. In addition, the use in industry (in construction, in the creation of new machines and mechanisms) of the principles of organization of living beings (bionics) brings at present and will give in the future a significant economic effect.

In the future, the practical importance of biology will increase even more. This is due to the rapid growth of the world's population, as well as the ever-increasing number of urban populations not directly involved in agricultural production. In such a situation, the basis for increasing the amount of food resources can only be the intensification of agriculture. An important role in this process will be played by the breeding of new highly productive forms of microorganisms, plants and animals, as well as the rational, scientifically substantiated use of natural resources.

Section 1. Origin and initial stages of development of life on Earth

Man has always sought to know the world around him and determine the place that he occupies in it. How did modern animals and plants originate? What led to their striking diversity? What are the reasons for the disappearance of fauna and flora of distant times? What are the future ways of development of life on Earth? Here are just a few questions from the huge number of mysteries, the solution of which has always worried mankind. One of them is the very beginning of life. The question of the origin of life at all times, throughout the history of mankind, was not only of cognitive interest, but also of great importance for the formation of people's worldview.

Chapter 1. The diversity of the living world. Basic properties of living matter

Full, full of miracles mighty nature.

A. S. Pushkin

The first living beings appeared on our planet about 3 billion years ago. From these early forms arose innumerable species of living organisms, which, having appeared, flourished for a more or less long time, and then died out. From pre-existing forms, modern organisms also originated, forming four kingdoms of wildlife: more than 2.5 million animal species, 600 thousand plant species, a significant number of various fungi, as well as many prokaryotic organisms.

The world of living beings, including humans, is represented by biological systems of different structural organization and different levels of subordination, or consistency. It is known that all living organisms are made up of cells. A cell, for example, can be both a separate organism and part of a multicellular plant or animal. It can be quite simply arranged, like a bacterial one, or much more complex, like the cells of unicellular animals - the Protozoa. Both a bacterial cell and a Protozoan cell represent a whole organism capable of performing all the functions necessary to ensure life. But the cells that make up a multicellular organism are specialized, that is, they can perform only one function and are not able to exist independently outside the body. In multicellular organisms, the interconnection and interdependence of many cells leads to the creation of a new quality that is not equivalent to their simple sum. The elements of the body - cells, tissues and organs - in total do not yet represent a holistic organism. Only their combination in the order historically established in the process of evolution, their interaction, forms an integral organism, which has certain properties.

1.1. Levels of organization of living matter

Wildlife is a complexly organized hierarchical system (Fig. 1.1). Biologists, based on the characteristics of the manifestation of the properties of living things, distinguish several levels of organization of living matter.

1. Molecular

Any living system, no matter how complex it may be organized, functions at the level of interaction of biological macromolecules: nucleic acids, proteins, polysaccharides, and other important organic substances. From this level, the most important processes of the body's vital activity begin: metabolism and energy conversion, transmission of hereditary information, etc.

2. Cellular

A cell is a structural and functional unit, as well as a unit of reproduction and development of all living organisms living on Earth. There are no non-cellular life forms, and the existence of viruses only confirms this rule, since they can exhibit the properties of living systems only in cells.

Rice. 1.1. Levels of organization of living matter (on the example of a separate organism). The body, like all living nature, is built on a hierarchical principle.

3. Fabric

Tissue is a collection of similar cells and intercellular substance, united by the performance of a common function.

4. Organ

In most animals, an organ is a structural and functional combination of several types of tissues. For example, human skin as an organ includes epithelium and connective tissue, which together perform a number of functions. Among them, the most important is protection.

5. Organismic

An organism is an integral unicellular or multicellular living system capable of independent existence. A multicellular organism is formed by a combination of tissues and organs specialized in performing various functions.

6. Population-species

A set of organisms of the same species, united by a common habitat, creates a population as a system of supraorganismal order. In this system, the simplest, elementary evolutionary transformations are carried out.

7. Biogeocenotic

Biogeocenosis is a set of organisms of different species and organization of varying complexity with all the factors of their specific habitat - components of the atmosphere, hydrosphere and lithosphere. It includes: inorganic and organic substances, autotrophic and heterotrophic organisms. The main functions of biogeocenosis are the accumulation and redistribution of energy.

8. Biospheric

The biosphere is the highest level of organization of life on our planet. It distinguishes living matter- the totality of all living organisms, inanimate, or inert, matter And biomaterial. According to tentative estimates, the biomass of living matter is about 2.5 × 10 12 tons. Moreover, the biomass of organisms living on land is 99.2% represented by green plants. At the biospheric level, there is a circulation of substances and the transformation of energy associated with the vital activity of all living organisms living on Earth.

Every living organism represents a multilevel system with a different rate of complexity and coordination. All the signs of vital activity – metabolism, transformation of energy, and transference of genetic information – start with interactions of macromolecules. However, only the cell, where the processes of interactions between molecules are in the spatial order, can be considered as structural and function as a unit of living organisms. In multicellular bodies coordinated activity of many cells enables the appearance of qualitatively new formations – tissues and organs, specialized to definite functions of the organism.

Anchor points

1. Organic molecules make up the bulk of the dry matter of the cell.

2. Nucleic acids provide storage and transmission of hereditary information in all cells.

3. At the heart of metabolic processes are the interactions of organic molecules with each other.

4. The cell is the smallest structural and functional unit of the organization of living organisms.

5. The emergence of tissues and organs in multicellular animals and plants marked the specialization of body parts according to their functions.

6. The integration of organs into systems has led to an even greater strengthening of body functions.

Review questions and assignments

1. What are organic molecules and what is their role in providing metabolic processes in living organisms?

2. What are the fundamental differences between the cells of living organisms belonging to different kingdoms of nature?

3. What is the essence of cytological, histological and anatomical methods of studying living matter?

4. What is called biogeocenosis?

5. How can the Earth's biosphere be characterized?

6. What metabolic processes take place at the level of the biosphere? What is their fundamental importance for living organisms living on our planet?

Using the vocabulary of the headings "Terminology" and "Summary", translate into English the paragraphs of "Reference points".

Terminology

For each term indicated in the left column, select the corresponding definition given in the right column in Russian and English.

Select the correct definition for every term in the left column from English and Russian variants listed in the right column.

Issues for discussion

In your opinion, what is the need to distinguish between different levels of organization of living matter?

Indicate the criteria for distinguishing different levels of organization of living matter.

What is the essence of the basic properties of living things at different levels of organization?

How do biological systems differ from inanimate objects?

1.2. Criteria for living systems

Let us consider in more detail the criteria that distinguish living systems from objects of inanimate nature, and the main characteristics of life processes that distinguish living matter into a special form of existence of matter.

Features of the chemical composition. The composition of living organisms includes the same chemical elements as in objects of inanimate nature. However, the ratio of various elements in living and non-living is not the same. The elemental composition of inanimate nature, along with oxygen, is mainly represented by silicon, iron, magnesium, aluminum, etc. In living organisms, 98% of the chemical composition falls on four elements - carbon, oxygen, nitrogen and hydrogen. However, in living bodies, these elements participate in the formation of complex organic molecules, the distribution of which in inanimate nature is fundamentally different both in quantity and in essence. The vast majority of organic molecules in the environment are waste products of organisms.

Living matter contains several main groups of organic molecules, which are characterized by certain specific functions and, for the most part, are irregular polymers. Firstly, these are nucleic acids - DNA and RNA, the properties of which provide the phenomena of heredity and variability, as well as self-reproduction. Secondly, these are proteins - the main structural components and biological catalysts. Thirdly, carbohydrates and fats are the structural components of biological membranes and cell walls, the main sources of energy needed to ensure vital processes. And finally, a huge group of various so-called "small molecules" that take part in numerous and diverse metabolic processes in living organisms.

Metabolism. All living organisms are capable of exchanging substances with the environment, absorbing substances necessary for nutrition from it and releasing waste products.

In inanimate nature, there is also an exchange of substances, however, in the non-biological cycle of substances, they are mainly simply transferred from one place to another or their state of aggregation changes: for example, soil is washed away, water turns into steam or ice.

Unlike metabolic processes in inanimate nature, in living organisms they have a qualitatively different level. In the circulation of organic substances, the most significant are the processes of transformation of substances - the processes of synthesis and decay.

Living organisms absorb various substances from the environment. As a result of a number of complex chemical transformations, substances from the environment are rearranged into substances characteristic of a given living organism. These processes are called assimilation or plastic exchange.

Rice. 1.2. Metabolism and energy conversion at the body level

The other side of metabolism - processes dissimilation, as a result of which complex organic compounds decompose into simple ones, while their similarity with the substances of the body is lost and the energy necessary for biosynthesis reactions is released. Therefore, dissimilation is called energy exchange(Fig. 1.2).

Metabolism provides homeostasis organism, i.e., the invariance of the chemical composition and structure of all parts of the body and, as a result, the constancy of their functioning in continuously changing environmental conditions.

A single principle of structural organization. All living organisms, no matter which systematic group they belong to, have cellular structure. The cell, as already mentioned above, is a single structural and functional unit, as well as a unit of development for all the inhabitants of the Earth.

Reproduction. At the organismic level, self-reproduction, or reproduction, manifests itself in the form of asexual or sexual reproduction of individuals. When living organisms reproduce, offspring usually resemble their parents: cats reproduce kittens, dogs reproduce puppies. From poplar seeds, poplar grows again. The division of a single-celled organism - an amoeba - leads to the formation of two amoebas, completely similar to the mother cell.

In this way, reproduction – This is the property of organisms to reproduce their own kind.

Thanks to reproduction, not only whole organisms, but also cells, cell organelles (mitochondria, plastids, etc.) after division are similar to their predecessors. From one DNA molecule, when it is doubled, two daughter molecules are formed, completely repeating the original one.

Self-reproduction is based on matrix synthesis reactions, i.e., the formation of new molecules and structures based on the information contained in the DNA nucleotide sequence. Consequently, self-reproduction is one of the main properties of the living, closely related to the phenomenon of heredity.

Heredity. Heredity is the ability of organisms to transmit their characteristics, properties and features of development from generation to generation. A sign is any feature of the structure at various levels of organization of living matter, and properties are understood as functional features based on specific structures. Heredity is due to the specific organization of the genetic substance (genetic apparatus) – genetic code. The genetic code is understood as such an organization of DNA molecules, in which the sequence of nucleotides in it determines the order of amino acids in a protein molecule. The phenomenon of heredity is ensured by the stability of DNA molecules and the reproduction of its chemical structure (replication) with high accuracy. Heredity provides material continuity (the flow of information) between organisms in a number of generations.

Variability. This property is, as it were, the opposite of heredity, but at the same time it is closely related to it, since in this case hereditary inclinations change - the genes that determine the development of certain traits. If the reproduction of matrices - DNA molecules - always occurred with absolute accuracy, then during the reproduction of organisms, only the features that existed before would be inherited, and the adaptation of species to changing environmental conditions would be impossible. Consequently, variability – This is the ability of organisms to acquire new traits and properties as a result of changes in the structure of hereditary material or the emergence of new combinations of genes.

Variability creates diverse material for natural selection, i.e., the selection of the most adapted individuals for specific conditions of existence in natural conditions. And this, in turn, leads to the emergence of new forms of life, new types of organisms.

Growth and development. The ability to develop is a universal property of matter. Development is understood as an irreversible directed regular change in objects of animate and inanimate nature. As a result of development, a new qualitative state of the object arises, as a result of which its composition or structure changes. The development of a living form of the existence of matter is represented individual development, or ontogeny, And historical development, or phylogenesis.

During ontogenesis, the individual properties of organisms gradually and consistently manifest themselves. This is based on the phased implementation of hereditary programs. Development is accompanied by growth. Regardless of the method of reproduction, all daughter individuals formed from one zygote or spore, kidney or cell, inherit only genetic information, that is, the ability to show certain signs. In the process of development, a specific structural organization of the individual arises, and an increase in its mass is due to the reproduction of macromolecules, elementary structures of cells, and the cells themselves.

Phylogeny, or evolution, is the irreversible and directed development of living nature, accompanied by the formation of new species and the progressive complication of life. The result of evolution is the diversity of living organisms on Earth.

Irritability. Any organism is inextricably linked with the environment: it extracts nutrients from it, is exposed to adverse environmental factors, interacts with other organisms, etc. In the process of evolution, living organisms have developed and consolidated the ability to selectively respond to external influences. This property is called irritability. Any change in the environmental conditions surrounding the organism is an irritation in relation to it, and its reaction to external stimuli serves as an indicator of its sensitivity and a manifestation of irritability.

The reaction of multicellular animals to irritation is carried out through the nervous system and is called reflex.

Organisms that do not have a nervous system, such as protozoa or plants, are also devoid of reflexes. Their reactions, expressed in a change in the nature of movement or growth, are usually called taxis or tropisms, adding the name of the stimulus to their designation. For example, phototaxis is movement towards the light; chemotaxis is the movement of an organism in relation to the concentration of chemicals. Each kind of taxis can be positive or negative, depending on whether the stimulus acts on the organism in an attractive or repulsive way.

Under tropisms understand the specific nature of growth, which is characteristic of plants. So, heliotropism (from the Greek. helios - the Sun) means the growth of the ground parts of plants (stem, leaves) towards the Sun, and geotropism (from the Greek. geo - Earth) - the growth of underground parts (roots) towards the center of the Earth.

Plants are also characterized nastia- movements of parts of a plant organism, for example, the movement of leaves during daylight hours, depending on the position of the Sun in the sky, the opening and closing of the corolla of a flower, etc.

discreteness. The word discrete itself comes from the Latin discretus, which means intermittent, divided. Discreteness is a universal property of matter. So, from the course of physics and general chemistry, it is known that each atom consists of elementary particles, that atoms form a molecule. Simple molecules are part of complex compounds or crystals, etc.

Life on Earth also manifests itself in discrete forms. This means that a separate organism or other biological system (species, biocenosis, etc.) consists of separate isolated, i.e., isolated or limited in space, but nevertheless closely related and interacting parts that form a structural and functional unity . For example, any kind of organisms includes individual individuals. The body of a highly organized individual forms spatially limited organs, which, in turn, consist of individual cells. The energy apparatus of the cell is represented by individual mitochondria, the apparatus of protein synthesis - by ribosomes, etc. up to macromolecules, each of which can perform its function only being spatially isolated from others.

The discreteness of the structure of the body is the basis of its structural order. It creates the possibility of its constant self-renewal by replacing "worn out" structural elements (molecules, enzymes, cell organelles, whole cells) without stopping the function being performed. The discreteness of a species predetermines the possibility of its evolution through the death or elimination of unadapted individuals from reproduction and the preservation of individuals with traits useful for survival.

Autoregulation. This is the ability of living organisms living in continuously changing environmental conditions to maintain the constancy of their chemical composition and the intensity of the course of physiological processes - homeostasis. At the same time, the lack of intake of any nutrients from the environment mobilizes the body's internal resources, and the excess causes the storage of these substances. Such reactions are carried out in different ways due to the activity of regulatory systems - nervous, endocrine and some others. The signal for turning on one or another regulatory system can be a change in the concentration of a substance or the state of a system.

Rhythm. Periodic changes in the environment have a profound effect on wildlife and on the own rhythms of living organisms.

In biology, rhythm is understood as periodic changes in the intensity of physiological functions and shaping processes with different periods of fluctuations (from a few seconds to a year and a century). The daily rhythms of sleep and wakefulness in humans are well known; seasonal rhythms of activity and hibernation in some mammals (ground squirrels, hedgehogs, bears) and many others (Fig. 1.3).

Rhythm is aimed at coordinating the functions of the organism with the environment, that is, at adapting to periodically changing conditions of existence.

Energy dependence. Living bodies are "open" systems for energy entry. This concept is borrowed from physics. By "open" systems we understand dynamic, i.e., systems that are not at rest, stable only under the condition of continuous access to them by energy and matter from the outside. Thus, living organisms exist as long as they receive matter in the form of food from the environment and energy. It should be noted that living organisms, unlike objects of inanimate nature, are limited from the environment by shells (the outer cell membrane in unicellular organisms, the integumentary tissue in multicellular organisms). These shells impede the exchange of substances between the organism and the external environment, minimize the loss of matter and maintain the spatial unity of the system.

V. B. Zakharov, S. G. Mamontov, N. I. Sonin, E. T. Zakharova

Biology. General biology. Deep level. Grade 11

Foreword

Dear friends!

We continue to study the basics of general biological knowledge, which began in the 10th grade. The objects of our attention will be the stages of the historical development of wildlife - the evolution of life on Earth and the formation and development of ecological systems. To study these important issues in full, you will need the knowledge acquired last year, since the laws of heredity and variability lie at the heart of development processes. Particular attention in the textbook is given to the genetic mechanisms of evolution, the analysis of relationships between organisms, and the conditions for the sustainability of ecological systems.

It would not be an exaggeration to say that over the past fifty years, biology has developed noticeably faster than all other sciences. The revolution in biology began in the 1950s and early 1960s. XX century, when, after long labors and efforts, scientists finally managed to understand the material nature of heredity. Deciphering the structure of DNA and the genetic code was initially perceived as a solution to the Main Secret of Life. But history has shown that the great discoveries of the middle of the last century did not at all provide definitive answers to all the questions facing biology. They, in the words of a well-known scientist and popularizer of science, b. n. A. V. Markov, became rather a magical "golden key" that opened the mysterious door, behind which new labyrinths of the unknown were discovered.

The flow of new discoveries does not dry out even today. There is so much new knowledge that almost all working hypotheses, generalizations, rules, laws constantly have to be revised and improved. However, classical concepts are rarely discarded completely. Usually we are talking about extensions and refinements of the limits of their application; likewise, for example, in physics, the theory of relativity did not at all cancel the Newtonian picture of the world, but clarified, supplemented and expanded it.

Evolution is a scientific fact. In this respect, biologists are quite unanimous; moreover, it is considered necessary to consider any biological issues in various fields of knowledge through the prism of evolutionary teaching. That evolution proceeds spontaneously, without the control of intelligent forces, for natural reasons, is a generally accepted, perfectly working hypothesis, the rejection of which is highly undesirable, because it would make wildlife largely unknowable. Details, mechanisms, driving forces, patterns, evolutionary paths - this is the main subject of biologists' research today.

What is the totality of the ideas about evolution accepted by the scientific community today? Often it is called "Darwinism", but so many clarifications, additions and rethinkings have already been superimposed on Darwin's original teaching that such a name only confuses. Sometimes they try to equate this set with the synthetic theory of evolution (STE). The further development of evolutionary biology did not refute the achievements of the past, there was no “collapse of Darwinism”, which journalists and writers far from biology love to talk about, however, subsequent discoveries significantly changed our understanding of the evolutionary process. This is a normal process of development of science, as it should be.

The range of issues that you will meet in grade 11 is very wide, but not all of them are covered in detail in the textbook. For a more thorough study of certain issues of biology, a list of additional literature is given at the end of the book. In addition, not all regularities are known or fully understood, because the complexity and diversity of life are so great that we are only beginning to understand some of its phenomena, while others are still waiting to be studied.

As you work through your textbook, constantly evaluate your progress. Are you satisfied with them? What new things do you learn when studying a new topic? How can this knowledge be useful to you in everyday life? If some material seems difficult to you, ask your teacher for help or use reference books and Internet resources. You will find a list of recommended Internet sites at the end of the tutorial.

The authors express their gratitude to Academician of the Russian Academy of Medical Sciences Professor V.N. Yarygin for supporting their creative efforts, Yu.P. Dashkevich and Professor A.G. Mustafin for valuable comments made by them during the preparation of this edition of the textbook.

Laureate of the Prize of the President of the Russian Federation in the field of education, Academician of the Russian Academy of Natural Sciences, Professor V. B. Zakharov

Section 1. The doctrine of the evolution of the organic world

The world of living organisms has a number of common features that have always caused a feeling of amazement in a person. Firstly, this is the extraordinary complexity of the structure of organisms, secondly, the obvious purposefulness, or adaptive nature, of many features, and thirdly, the huge variety of life forms. The questions raised by these phenomena are quite obvious. How did complex organisms arise? Under the influence of what forces their adaptive features were formed? What is the origin of the diversity of the organic world and how is it maintained? What place does man occupy in the organic world and who are his ancestors?

In all ages, mankind has tried to find answers to these and many other similar questions. In pre-scientific societies, explanations resulted in legends and myths, some of which served as the basis for various religious teachings. The scientific interpretation is embodied in the theory of evolution, which is the subject of this section.

Chapter 1 evolutionary doctrine

Everything is and is not, because, although the moment will come when it is, it immediately ceases to be ... The same thing is both young and old, and dead and alive, then it changes into this, this, changing, becomes again topics.

Heraclitus

The main work of Charles Darwin "The Origin of Species", which radically changed the idea of ​​wildlife, appeared in 1859. This event was preceded by more than twenty years of work on the study and comprehension of the rich factual material collected both by Darwin himself and by other scientists. In this chapter, you will get acquainted with the basic premises of evolutionary ideas and the first evolutionary theory of J. B. Lamarck; learn about Ch. Darwin's theory of artificial and natural selection, as well as modern ideas about the mechanisms and speed of speciation.

Currently, more than 600 thousand plants and at least 2.5 million animal species, about 100 thousand species of fungi and more than 8 thousand prokaryotes, as well as up to 800 species of viruses have been described. Based on the ratio of described and not yet identified modern species of living organisms, scientists make an assumption that about 4.5 million species of organisms are represented in modern flora and fauna. In addition, using paleontological and some other data, the researchers calculated that in the entire history of the Earth, at least 1 billion species of living organisms lived on it.

Let us consider how in different periods of human history people imagined the essence of life, the diversity of living things and the emergence of new forms of organisms.

1.1. The history of ideas about the development of life on Earth

The first attempt to systematize and generalize the accumulated knowledge about plants and animals and their life activity was carried out by Aristotle (4th century BC), but long before him, many interesting information about the organization of living nature was presented in the literary monuments of various peoples of antiquity, mainly associated with agronomy, animal husbandry and medicine. Biological knowledge itself is rooted in ancient times and is based on the direct practical activities of people. According to the rock paintings of the Cro-Magnon man (13 thousand years BC), it can be established that already at that time people could well distinguish a large number of animals that served as the object of their hunt.

1.1.1. Ancient and medieval ideas about the essence and development of life

In ancient Greece in the VIII-VI centuries. BC e. in the bowels of a holistic philosophy of nature, the first rudiments of ancient science arose. The founders of Greek philosophy Thales, Anaximander, Anaximenes and Heraclitus were looking for a material source from which the world arose due to natural self-development. For Thales, this first principle was water. Living beings, according to the teachings of Anaximander, are formed from indefinite matter - "apeiron" according to the same laws as objects of inanimate nature. The third Ionian philosopher, Anaximenes, considered the material principle of the world to be air, from which everything arises and into which everything returns. He also identified the human soul with air.

The greatest of the ancient Greek philosophers was Heraclitus of Ephesus. His teaching does not contain special provisions about living nature, but it was of great importance both for the development of all natural science and for the formation of ideas about living matter. Heraclitus for the first time introduced into philosophy and the science of nature a clear idea of ​​constant change. The scientist considered fire to be the beginning of the world. He taught that all change is the result of a struggle: "Everything arises through struggle and out of necessity."