Of the currently known 108 chemical elements only a few are part of living organisms. First of all, these are macroelements that are available in large quantities in nature and are necessary for all biological objects: H, C, O, N, S, P, Ca, Mg, K, Fe, and for animals also Na and CI. To a lesser extent, trace elements Cu, Mn, Zn, Mo, Co, as well as F, J, Se (for animals) and B (for plants) are used for the vital activity of organisms.
For the chemical basis of life highest value have mineral salts and the corresponding cations and anions: sodium and potassium ions provide an electrical discharge on cell membranes and the transmission of electrical impulses through nerves and muscles, thus controlling their work; calcium ions are the basis of bone tissue, and are also involved in muscle contraction; phosphorus is included in organic compounds - biological energy accumulators and (together with calcium) in the composition of the bones of the skeleton; chloride ions together with sodium ions create osmotic pressure in the blood, lymph and plasma. Hydrochloric acid, which is secreted in the stomach of humans and animals, plays an important role in digestion. Iron is found in the blood pigment, hemoglobin, which is an oxygen carrier. Iron and copper are part of the electron carriers in the energy-producing cellular organelles - mitochondria, and are also part of some enzymes. Magnesium forms the basis of the chlorophyll molecule and provides the main photochemical reaction in living organisms - the synthesis of organic substances from carbon dioxide and water.
Iodine is an element of such an important compound as thyroid hormone. Lack of iodine in food causes a serious disease - endemic goiter. This disease, caused by a lack of iodine in the soil, is common in a number of regions of the world, for example, in the Urals, in the Carpathians and other regions. Iodine and potassium compounds help protect the human body from the effects of ionizing radiation. Vitamin B12 contains cobalt. Some vital enzymes and hormones, such as insulin, contain zinc.
Number one in terms of numbers chemical compounds occupies water (in the human body it is about 60%, and in the jellyfish - more than 96%). Water serves as a solvent, means of internal transport, and medium for most metabolic processes. A significant part of the remaining inorganic components is in aqueous solution.
The number of organic compounds, consisting mainly of C, H, O, N, S and P, in living organisms is extremely large. They belong mainly to four classes - proteins, nucleic acids, carbohydrates and lipids (or fats). Proteins predominate quantitatively in animals, carbohydrates in plants.
Proteins have a number of important properties and functions: they are involved in the construction of cells and tissues, they are biological enzymes - catalysts, hormones, protective substances, etc. Proteins are involved in energy transformation processes. For example, muscle proteins react with adenosine triphosphoric acid molecules and cleave the energy-rich chemical bond in them. Under the influence of the released energy, muscle protein contracts. Thus, chemical energy with the participation of muscle proteins is converted into mechanical energy - one type of energy is transformed into another. Proteins can also serve as a source of energy for cells.
If viruses or bacteria enter the body of animals and humans, then special proteins - antibodies - are produced to protect against them. These proteins neutralize pathogens, delaying their reproduction in the body. This mechanism of resistance to diseases is called immunity. To increase immunity, ready-made antibodies (vaccines) obtained from an ill animal or person are injected into the blood, i.e. from the organism in which they are already produced. Proteins are an important part of all structures of cells and organisms. Skin, muscles, hair and wool, elastic walls of blood vessels, etc. are structures based on proteins. Nucleic acids, like proteins, are involved in life processes, in the transmission of hereditary traits, and also in protein synthesis.
Carbohydrates play an important role in the life of organisms, among which simple sugars (monosaccharides) stand out: glucose, fructose, galactose. They have one chemical formula(С6Н1206) and differ only in the spatial structure of the molecule. Glucose and fructose are found in fruits and berries. Galactose is part of the milk sugar - lactose. Glucose molecules under the action of enzymes can be combined into long and branched polymer chains - polysaccharides - starch and glycogen. Starch is a storage form of nutrients in plant cells. Due to the high content of starch in wheat, corn, rice, potatoes, these crops are widespread on our planet and are the most important food in most countries. Glycogen accumulates in animal and human cells. This polysaccharide differs from starch in the greater branching of its molecules. Especially a lot of glycogen is found in liver cells, as well as in muscles. The breakdown and oxidation of carbohydrates allows the cell to obtain chemical energy.
Lipids (fats) are included in cell structures and cell membranes, where, in combination with proteins, they regulate the absorption and excretion of substances by cells. Lipids, like carbohydrates, are energy sources for cells and store nutrient reserves. Lipids include glycerol and various fatty acids. As needed, lipids are broken down by enzymes, after which fatty acids are oxidized stepwise, releasing a large amount of energy. The end products of fat burning are carbon dioxide and water.
The composition of cells always includes a small amount of organic substances of various composition that regulate the work of the cell, united in a group called vitamins. These vital compounds can only be synthesized by plants and bacteria. They enter the body of animals and humans with food. Most vitamins are part of the protein part of enzymes. Now more than 20 vitamins are known, necessary for a person. In the absence or deficiency of any vitamin, the work of certain enzymes, the course of biochemical reactions and the normal functioning of cells are disrupted. This leads to diseases (avitaminosis) and can even cause death of the organism.
The physiological signs of the living can be established on the basis of such general concept, What's up. Life can be defined as an active maintenance and reproduction of specific structures, proceeding with the expenditure of energy received from outside. From this definition follows the need for a constant connection of the organism with the environment, carried out through the exchange of matter and energy. In other words, the body adapts (adapts) to a certain environment. From this follows a number of properties of the living, which, however, are relative.
Living organisms are able to grow and develop, i.e., increase in size and mass, with the preservation (or appearance) in the course of the process of the general structural features characteristic of an adult, i.e., an individual (individual) capable of reproducing.
Each organism receives from the environment the substances and energy it needs, and gives it those substances and energy that it cannot use as a result of nutrition, respiration and excretion. The energy received from outside is used to maintain the orderliness of biological structures. Living cells, tissues or the whole organism are able to respond to external and internal influences, i.e., to detect irritability, which underlies their adaptation to changing environmental conditions. Irritability manifests itself at all levels of development of life and is accompanied by changes in metabolism, electrical potential, and the state of cells. In highly organized animals, irritability manifests itself through higher nervous activity (including reflexes) and consciousness (in humans).
Continuity and succession of life provide the inherent property of all organisms to reproduce their own kind - reproduction. Closely related to reproduction is the phenomenon of heredity (transfer of the characteristics of an organism from generation to generation), when descendants, having passed approximately the same path of individual development as their parents, again leave offspring similar to themselves. Descendants resemble their ancestors not only externally, but also in internal structure. No inheritance chemical features organism external resemblance would be impossible. There are no such phenomena in the inorganic world.
One of the most striking signs of a huge number of living organisms, primarily animals. - the ability to move. But far from all organisms show their living nature with movements that are noticeable to the human eye. For example, in fungi, trees, coral polyps, etc., movement occurs within a living organism and serves to transport weight from one part of the body to another.
In the inorganic world, there are prototypes of similar signs: the growth of crystals, the attraction of metal filings to a magnet, the bending of a bimetallic plate when heated, etc. But these objects do not have an active reaction to the environment.

environment, their actions are not purposeful. The exception is technical devices created by man on the principle of living organisms. Organic substances isolated from living organisms or synthesized in the course of experiments also do not exhibit the properties of a living thing.
The above signs of living organisms, being necessary, cannot serve as sufficient criteria for an unmistakable separation of animate and inanimate nature. To them must be added signs of the structural organization of life. The living acts in the form of certain formations - living organisms with a complex structural organization, in which molecular, subcellular, cellular, organ-tissue and organismal levels can be distinguished.
The molecular level of organization reflects the structure of proteins, their functions, the role of nucleic acids in the storage and implementation of genetic information in biological synthesis processes. important compounds. At this level of organization, the main research in biotechnology and genetic engineering is carried out, since many properties of the organism are determined precisely by this level.
The subcellular, or supramolecular, level characterizes the organization, structure and functions of various cellular structures - chromosomes, mitochondria, ribosomes, etc. Each of these cellular structures in all living organisms has its own, only inherent properties to ensure the life of the cell. Thus, chromosomes are responsible for storing and transmitting hereditary information (genetic code); mitochondria supply the cell with energy for existence; chloroplasts located in plant cells and containing chlorophyll, I transform! solar energy to energy chemical bonds; with the participation of ribosomes, protein molecules are synthesized, and special structures - lysosomes - contain enzymes that break down biopolymers.
The cellular level of organization is associated with the morphological organization of the cell, the specialization of cells during the development of the organism, the functions cell membrane, mechanisms and regulation of cell division. Research at the scrap level allows solving the most important problems of medicine, in particular, the treatment of oncological diseases.
The organ-tissue level of organization reflects the structure and functions of individual organs and their constituent tissues.
The organismic level is associated with the study of individuals and their inherent, as a whole, structural features, mechanisms of adaptation (adaptation) and behavior.
The division of living matter according to the levels of organization, although it reflects the objective reality, is at the same time conditional. For example, the problems of evolution or individual development should be considered taking into account the molecular, subcellular, cellular and organ tissue levels. Representing a set of interrelated and interacting elements, all levels of organization are combined into a single biological system. This biological system has the properties of integrity (i.e., the properties of the system are not reduced to the sum of the properties of the elements), relative stability, and the ability to adapt in relation to the external environment, development, self-reproduction and evolution.
The origin of all earthly beings from a common root is confirmed by far-reaching coincidences in their fundamental features. In nature, related characters are often found in organisms that are extremely distant from each other. The main features of the similarity of the evolutionary unity of all living beings are manifested in many directions. So, all organisms have a very close chemical composition, in which carbon is the most important building element. For example, in glucose, the carbon content reaches more than 30%. Protein molecules of all organisms are built from the same 20 amino acids, while in the tissues of living beings there are more than 100 amino acids that are not part of proteins. The bodies of almost all organisms are made up of cells (viruses are an exception). Animal and plant cells are built according to a single plan. The vast majority of organisms have cells with a cell nucleus. The basic scheme of the structure of the nucleus is the same for animals and plants. The division of such cells is carried out in a single, indirect way, while the daughter cells receive the same number of chromosomes that was contained in the mother cell. The formation of germ cells in all animals and plants is preceded by a process of reduction (halving) the number of chromosomes. The principles of building the genetic code are the same for all organisms. And the mechanism of copying hereditary information in all living beings is realized by doubling nucleic acid molecules. In addition, the main substances responsible for respiration (chlorophyll in plants and hemoglobin in animals) are very similar in chemical composition.
All these data testify to the unity of the origin of animals and plants, as well as to the relationship of all living organisms descended from common ancestors.

VIRUSES- non-cellular form of life, occupying an intermediate position between animate and inanimate nature.

Each viral particle consists of DNA or RNA and a shell - a capsid, mainly of a protein nature. Apparently, viruses originated from organisms that have lost their cellular structure, or from the genetic material of the "host" cells, part of which has acquired independence. The peculiarity of viruses is that they can only reproduce in living cells. Viral DNA or RNA is integrated into the genetic apparatus of the host cell and forces the cell to synthesize new proteins for the virus envelope and new viral genetic material. Under the influence of the embedded virus, the cell produces enzymes that destroy it, sometimes releasing hundreds of new viral particles. The sizes of viruses are from 15 to 300 nm.

Viruses were discovered in 1892 by the Russian scientist D.I. Ivanovsky. Most viruses are the cause of dangerous human diseases, including smallpox, measles, rabies, polio, influenza, acute respiratory infections, cancer and AIDS. Viruses can infect not only animals, but also plants and bacterial organisms. Viruses that infect plants are called phytoviruses, they penetrate plants only in places of mechanical damage, and their carriers are most often insects (aphids) or mites. Among the viral diseases of plants, such as tobacco mosaic, dwarf bushiness of tomatoes, bronze fruit, strokes or spotting on the perianths of tulips are known. Not always the defeat of a plant by viruses leads to its death, although the yield of diseased plants decreases. It is possible to fight phytoviruses, one of the ways is to breed virus-free plants by growing meristems of pieces of educational tissue on nutrient media.

Viruses that infect bacteria are called bacteriophages. The phage attaches to the bacterial cell wall and introduces its genetic material into the bacterial cell, while the phage shell, which has the shape of an ixahedral head, remains outside the bacterial cell, attaching to it with a “tail”, in which a hollow rod and a plate with spikes and filaments are distinguished , on which the features of bacteriophage attachment depend. The envelope of the virus acts like a syringe, injecting the genetic material of the virus into the cell. Bacteriophages were first described by F. Twort in 1915.

Many diseases caused by viruses are successfully treated today. Back in the 18th century E. Jenner found that farmers who had cowpox did not become infected with dangerous smallpox. Thanks to this observation, a grafting technique was proposed. Later, vaccinations became the most common thing, this led to the fact that smallpox disappeared on Earth. Unfortunately, vaccination is not always effective: they have not yet learned how to treat AIDS and a number of oncological diseases that are of a viral nature.

All viruses are conditionally divided into simple (described above) and complex, which, in addition to the proteins of the capsid and nucleic acid, may contain a lipoprotein membrane, carbohydrates and non-structural proteins - enzymes. The length of some complex viruses reaches 2000 nm.

Viruses exist in two forms: resting (extracellular) and reproducing (intracellular). Almost all viruses can only be seen with an electron microscope.

BACTERIA- prokaryotic cells of various shapes (balls, rods, spirals, etc.), in which the genetic material is not separated from the cytoplasm by a nuclear membrane, but there is a cell wall made of carbohydrate - murein. Cells are either solitary or form small groups united in short filaments.

Bacteria belong to heterotrophic, chemosynthetic or photosynthetic organisms, some are capable of nitrogen fixation. Bacteria are commonly referred to as microbes. Bacteria, the smallest living organisms, appeared on the planet about 3.5 billion years ago and over 2 billion years formed a biosphere similar to the modern one (with the advent of cyanobacteria molecular oxygen began to accumulate in the air, which created conditions for the evolution of aerobes).

Bacteria were first noticed in late XVII v. Dutch naturalist A. van Leeuwenhoek in the simplest microscope - a magnifying glass from one tiny drop-shaped lens. The sizes of bacterial cells range from 0.5 to 5 microns. Some bacteria have flagella that enable them to move, others are able to move by changing the shape of the cell, for example, crawling serpentine along a solid surface.

Prokaryotes reproduce by simple cell division, sometimes by budding. Under favorable conditions, bacteria grow very quickly, sometimes as coli, doubling the population in 20 minutes. Under unfavorable conditions, bacteria form spores, becoming covered with a dense shell - a kind of resting stage. In the form of spores, bacteria are able to tolerate sharp temperature fluctuations and remain viable for decades.

Among bacteria, there are certain species that live in an oxygen-free environment - they are called anaerobic bacteria. Distinguish anaerobes obligate, for them, oxygen is a deadly poison, and optional, which can live in both anoxic and oxygen-rich environments.

Bacteria can be divided into useful for other organisms and harmful - the latter more. Among the useful ones, for example, are lactic acid bacteria that can turn milk into yogurt, kefir or koumiss. They also contribute to the formation of sour dough, cheese, sauerkraut, silage. Many bacteria perform the function decomposers in biogeocenoses, processing dead organic matter into minerals.

MUSHROOMS- lower eukaryotes (i.e. have a well-formed nucleus and nuclear DNA). To date, there are about 100 thousand species of mushrooms. Mushrooms stand out in an independent kingdom, the representatives of which differ from both animals and plants.

Fungi reproduce vegetatively, asexually or sexually. Vegetative reproduction can be carried out by fragments of hyphae, which separate and give rise to a new mycelium. Asexual reproduction occurs with the help of spores, located either inside the mycelium in sporangia (special receptacles), or on the surface in specialized cells - conidiophores. Spores can be motionless, dressed in a shell, and mobile, with a flagellum that facilitates their movement. (zoospores). The forms of the sexual process in fungi are very diverse. During sexual reproduction, the fusion of germ cells - gametes formed in special organs - gametangia. When gametes of equal size merge, it is customary to talk about isogamy; at the fusion of gametes of different sizes - about heterogamy; in the case when a stationary cell (ovum) merges with a mobile cell (sperm), they speak of oogamy. In fungi, gametangia, not differentiated into gametes, and ordinary vegetative cells of the mycelium can also merge. In some fungi (yeast), another method of vegetative propagation is known - budding.

In the taxonomy of fungi, there is a division into several classes (based on the types of the sexual process, the development of spores, the nature of flagella, etc.).

Another class - BASIDIOMYCETES, includes more than 30 thousand species of fungi that form fruiting bodies, in which in special large cells basidia controversy is brewing. Basidiomycetes are subdivided into lamellar (champignons, russula, milk mushrooms, mushrooms) and tubular (butter, white, boletus) mushrooms. Raincoats, tinder fungi, pale grebe, fly agaric, smut and rust fungi, veil, trellis and many others, not only from the temperate climate zone, but also from the tropics, also belong to this class.

The Latin name for mushrooms "mycota" was derived from the Greek name for champignons - "mikos". Today, the science that studies fungi is called mycology. In Russian, mushrooms until the 16th century. called "lips". Mushrooms have been known to man since time immemorial, they have long been eaten, many mushrooms have been used in ritual ceremonies (for example, those that can cause hallucinations). Images of mushrooms were found on the walls of Mayan temples, among the rock carvings made by an ancient man in Chukotka. The first attempt to classify mushrooms was made by Pliny the Elder (1st century AD) in his work "Natural History" - he divided them into two groups: edible and inedible. Carl Linnaeus in "The System of Nature" in 1735 described 95 species of mushrooms. For a long time, mushrooms were included in the plant kingdom, but a rigorous study made it possible at the end of the 20th century. separate them into an independent kingdom. Foreign mycologists did a lot for this: the Tyulian brothers, Anton de Bari, P. A. Saccardo; Russian scientists: M. S. Voronin, S. G. Navashin, A. A. Yachevsky, L. I. Kursanov, and others.

There are three types of lichens: LIQUID, or CRUSTIC(in the form of a film, often painted, on stones, walls of buildings, etc.); SHEETS(in the form of plates adherent to the surface of the substrate) and BUSH, looking like small bushes growing on the surface of the earth or leading an epiphytic lifestyle (for example, deer moss). Lichens mainly dominate the vegetation cover of the tundra, although they are found almost everywhere: from the ice floes of Antarctica to the humid tropics of Indonesia. The fact is that the lichen body - the thallus uses the substrate only as a basis for attachment. Lichens grow very slowly, some of them grow by no more than 1 mm per year. The conventional wisdom that lichens are not afraid of anything but air pollution is not without foundation. However, it turns out that for some lichens, for example, a number of cladonia species, even anthropogenic pollution is not an obstacle to growth. Cladonia is able to grow on soils containing a huge amount of heavy metals, almost within a radius of 1 km from the copper smelter. So, the lichen thallus consists of densely woven hyphae of fungi from the class of ascomycetes, or basidiomycetes, and unicellular algae from the green or blue-green divisions, located between fungal hyphae. Due to the presence of algae in its body, the lichen does not need foreign organic substances, it is able to synthesize them itself, which is why lichens can grow almost anywhere. The functions of fungi in lichens are to protect algae from mechanical damage and drying out and to supply algae with inorganic compounds.

There are three types of reproduction in lichens: vegetative, asexual and sexual. Vegetative propagation is most often observed, based on the ability of the lichen to regenerate from individual sections of its thallus. It is carried out by fragmentation of the thallus or with the help of special formations - soredia. Soredia - the smallest formations consisting of one or more algae cells and surrounded by fungal hyphae. Each of the lichen components can also reproduce in ways characteristic of fungi or algae. Lichens participate in the cycle of life on our planet, they secrete acids on the substrate to which they attach, partially destroying it, due to which prerequisites arise for the formation of a soil layer on which other organisms later settle. From lichen thalli obtained essential oils used in perfumery and medicine, as well as dyes for fabrics. Lichens are the main food for reindeer (reindeer moss - reindeer moss). There are almost no poisonous species among lichens, although the xanthoria they eat can have some poisonous effect on animals. Many lichens produce antibiotic substances. Some lichens can even be eaten by humans, for example, in the deserts of the Middle East, aspicilia, otherwise called lichen manna, is considered edible. In the diet of the Japanese there are dishes from edible umbilicaria. According to the structural features of the thalli, lichens are divided into classes, and in relation to substrates and environmental factors they are divided into several ecological groups, for example, epiphytic lichens growing on the trunks and branches of trees and shrubs include scale, bushy and leafy forms. Not all principles of the life of lichens are understood by scientists today - this results in some confusion in the taxonomic position of lichens in the system of the organic world. Until recently, lichens as a department were included in the plant kingdom, although some experts tend to consider lichens as an independent kingdom. The science that studies lichens is called lichenology.

PLANTS- eukaryotic organisms capable of synthesizing organic compounds CO 2 and H 2 O with the release of oxygen, using the energy of sunlight, i.e., carrying out photosynthesis; consisting of cells with dense membranes, usually cellulose; leading a mostly immobile lifestyle (Fig. 56). Plants form an independent kingdom and are subdivided into higher (300-350 thousand species) and lower (about 150 thousand species).

The branch of science concerned with the study of plants is called botany. The first dated information about plants is contained in the ancient manuscripts of the East. Botany as a science began with the ancient Greeks. Aristotle was engaged in the study of plants, but his student Theophrastus (370-285 BC) is rightfully considered the "father of botany". In two of his works - "History of Plants" and "On the Causes of Plants" - he laid the foundations for the classification of plants and described woody, herbaceous, shrubby and shrubby plants known at that time.

The plant kingdom is very heterogeneous, among its representatives there are real giants (eucalyptus trees have up to 120 m in height) and dwarfs (for example, the flowering plant wolfia stemless, whose shoot dimensions are measured in millimeters). TO higher include all plants, flowering and non-flowering, having roots and shoots. As a rule, higher plants grow on land, although there are also water ones: water lily, elodea, lotus. Higher plants are divided into departments: flowering (angiosperms), gymnosperms, ferns, horsetails, club mosses, bryophytes.

The body of higher plants is divided into organs, for example, in flowering plants have roots, shoots, flowers and fruits with seeds. The shoot, in turn, consists of a stem and leaves. The shoot carries out the function of photosynthesis and conduction of mineral and organic substances, and the root attaches the plant to the soil and extracts from it mineral substances dissolved in water. Roots and shoots are called vegetative organs, in addition to nutrition, they also perform the function of respiration. Flowers, fruits and seeds of angiosperms - reproductive organs, otherwise they are called reproductive, or generative, organs, thanks to them, seed reproduction and resettlement of plants occur. It should be noted that the reproduction of flowering plants can be carried out and vegetative organs: creeping shoots, stolons, rhizomes, tubers, bulbs, leaves, root suckers. Flowering (angiosperms) plants are represented by various life forms: trees, shrubs, shrubs, herbs and vines. Most plants are perennials, but herbs can be perennial, annual or biennial. According to the peculiarities in the structure of seeds, flowering plants are divided into two classes: monocots(onions, wheat) and dicots(beans, peas). According to the peculiarities in the structure of flowers, angiosperms are divided into families: rosaceae, legumes, asteraceae, cruciferous, solanaceous, cereal, lily etc. In the development cycle of flowering plants, the sporophyte (the plant itself, including the root and shoot) dominates, the gametophyte is represented by a pollen tube with sperm (male) and an eight-core embryo sac formed in the ovule (female). Flowering plants reproduce according to the principle double fertilization, discovered by S. G. Pavashin in 1898 in lilies. Ancestral forms of flowering plants were closely related to seed ferns. To date, there are about 250 thousand species of angiosperms. The economic importance of angiosperms is enormous: among them there are many food plants (wheat, rye, potatoes, tomatoes, corn, sugar cane, etc.); fodder (bluegrass, fescue); medicinal (valerian, rhodiola, plantain); technical (sunflower, soy, flax, hemp); decorative (peony, gladiolus, iris), etc.

Gymnosperms have unprotected ovules located openly on the seed scale of the cone (they do not have a true flower and fruit, like flowering plants). The sporophyte predominates in the development cycle. Among the gymnosperms, there are more evergreen trees (spruce, pine, cypress, thuja), deciduous trees (larch), shrubs (juniper) and creepers (ephedra) are less common. The form of leaf plates in gymnosperms is different: from lamellar (ginko, cycad) to needle-shaped (pine). There are about 600 species of gymnosperms on Earth; they originated in the Devonian from primitive heterosporous and tree-like ferns. In plant taxonomy, gymnosperms are divided into four classes: coniferous, cycad, oppressive and ginkgo. Conifers make up the majority and dominate the vegetation cover in the temperate climate zone. Gymnosperms reproduce with the help of wind due to the presence of air sacs in pollen from male cones. The sperm is transferred to the ovule (pollination), the pollen tube germinates to the ovule, and in the spring of the following year, fertilization takes place (the egg merges with the sperm); an embryo develops from the formed zygote, and by the autumn of the next year a seed is formed, after which at the end of winter the scales of the cone open and by the end of the second year the seeds spill out. The use of gymnosperms is extremely wide. Their seeds contain a lot of oil and are eaten; wood is used as a raw material for the pulp and paper and furniture industries; tannins are obtained from the bark, and during the dry distillation of wood (spruce), resin, rosin, and turpentine are produced; from the core of cycads, which contains a lot of starch, sago groats can be made using a technologically simple process. Many gymnosperms are long-lived, for example, California pines live up to 4.5 thousand years.

The department FERN, or FERN, unites over 9 thousand species of higher spore plants, probably descended from rhinophytes in the second half of the Paleozoic era (Devonian, Carboniferous). Ferns are widely distributed over the surface of the Earth, among them there are both tree-like ferns (in the tropics), and herbaceous perennials (in temperate latitudes), and even lianas. Ferns are divided according to their way of life into terrestrial, rocky, and aquatic. Many ferns grow in the forests of the temperate climate zone. In the Middle Urals, you can find such ferns as the nodule, shield, bracken, centipede, ostrich, grapevine, etc. The sporophyte of ferns is represented by a large perennial herbaceous plant, sometimes up to one and a half meters in height. A bunch of green leaves usually rises above the ground - wai, which are spirally arranged on an underground rhizome. Young leaves are folded into a "snail" and grow rather slowly. Adventitious roots leave the rhizome into the soil, firmly fixing the plant in the substrate. By August, ferns of temperate latitudes on the reverse side of wai form sporangia with spores collected in bunches - sori. The spore falls to the ground and germinates to form overgrowth(gametophyte), which looks like a small heart-shaped green plate. On the underside of this plate are rhizoids(root-like outgrowths that attach the gametophyte to the substrate) and genital organs: female (archegonia) and men's (anteridia). In the female organs, one immobile egg matures, in the male, polyflagellated spermatozoa are formed. After fertilization (in the presence of water), an embryo is formed, which eventually turns into an adult sporophyte. Many ferns are grown as indoor ornamental plants; but among them there are a large number of food species (bracken); medicinal (male shield); technical (azolla water fern in tropical Asia is used as a nitrogen fertilizer).

Representatives of the horsetail department, or wedge-shaped, are distributed everywhere except Australia and New Zealand. They grow in swamps, in forests, on arable land and are represented by perennial herbaceous plants. Horsetails have a jointed, branched rhizome with adventitious roots and aboveground shoots, usually of two types (vegetative - green, whorled branched, summer and brown - unbranched, bearing a spore-bearing spikelet at the top, spring). From the spores developing in spore-bearing spikelets, after they fall to the ground, growths grow. On the growths, as well as in ferns, the genital organs develop - antheridia and archegonia. After fertilization, a zygote is formed, then an embryo, and then an adult plant is formed - a sporophyte. In the distant past, coal horsetails - calamites reached 30 m, today the largest horsetail reaches 12 m, but not in height, but in length - this is one of the South American vines. In our latitudes, horsetails are found only up to 40-60 cm high: forest, field, meadow, wintering, marsh horsetail.

The Lycopsidium division includes about 400 species of mostly herbaceous plants with creeping stems, small linear-subulate leaves and adventitious roots. In mid-summer, spore-bearing spikelets form on the shoots. Spores ripen in spikelets, which, after falling on moist soil, germinate into a sprout. Antheridia and archegonia are formed on the growth, and after fertilization, just like in horsetails, an embryo develops, which eventually turns into an adult plant - a sporophyte. Club mosses are forest plants, occasionally found on the edges and along forest roads, sometimes along swamps. In our latitudes, club mosses grow: annual, club-shaped, flattened. In the Carboniferous period, when thick layers of coal arose, real giants were found among the club mosses - lepidodendron trees and sigillaria trees up to 30 m high. The length of modern club mosses does not exceed 3 m, and the height of spore-bearing spikelets rising above the surface is no more than 15-20 cm. The spores of club mosses are used in medicine.

The Department of Bryophytes includes about 25,000 species, usually terrestrial, of plants. Mosses are among the higher plants; although they do not have true roots, there are root-like outgrowths - rhizoids that attach mosses to the soil surface. The bryophyte shoot consists of a stem and small translucent wedge-shaped leaves. The height of the shoot usually does not exceed 20 cm. In temperate latitudes, mosses often form a continuous cover in spruce and mixed forests. Mosses are also found in swamps, and some of them, such as sphagnum, simply dominate swamp ecosystems, displacing all other competitors, with the exception of some berry shrubs. The life cycle of moss is dominated by the gametophyte. Mosses are mostly dioecious plants. At the tops of female shoots, female genital organs are formed, similar to small cones, in the expanded part of which the egg matures. Small, elongated sacs are formed on male shoots, in which spermatozoa mature. Mosses grow in thick turf, and in rainy weather, spermatozoa get to the eggs through the water. As a result of fertilization, a zygote is formed, from which a box on a long stem (sporophyte) develops directly on the female gametophyte. The box is equipped with a lid, inside there is a sporangium with spores. In dry weather, after the spores mature, the lid falls off, the box leans and the spores spill out onto the ground. On moist soil, the spore germinates with the formation of a thin green thread. The thread branches, buds are laid on it, from which new shoots of moss grow. Mosses are predominantly perennials. Systematics divide them into three classes: anthocerbaceae(distributed mainly in the tropics and subtropics); liverworts(marchation) and leafy mosses. The latter make up the majority and are divided into two subclasses: sphagnum, or peat, mosses and green mosses. The value of mosses is enormous. With incomplete decomposition of dead remains of sphagnum moss, peat deposits are formed, which is used as fuel; applied as a fertilizer; during dry distillation, phenols, paraffin, ammonia are obtained from peat, and alcohol and other materials are obtained by hydrolysis. Bryophytes have been known since the Carboniferous, their ancestors are considered to be rhinophytes.

The taxonomy of algae has not yet been developed well enough. To date, 12 divisions of algae are distinguished, although blue-green(prokaryotes) are often referred to as bacteria, and the division euglenoe algae are classified in the phylum Protozoa (Kingdom Animals). In the seas, algae are found in the range from the surface to a depth of 200 m.

Algae reproduce in different ways: unicellular - by cell division; colonial - the collapse of the colony; multicellular - with pieces of a torn thallus, as well as spores, like mushrooms: mobile zoospores with flagella, and motionless, carried by water. Some reproduce sexually. If sex cells of the same size merge, they talk about isogamy. The method of fertilization, in which gametes of different sizes (sex cells) unite, is called heterogamy. In the case when a motionless gamete (ovum) is fertilized by a mobile gamete (spermatozoon), they mean oogamy.

Sometimes gametes are not formed, but the contents of two cells simply merge (in multicellular algae with the formation of a cytoplasmic bridge); such a process is called conjugation(compound), is present, for example, in the filamentous algae spirogyra.

The role of algae in the biosphere as primary producers is great. organic matter. They are no less important as the oldest photosynthetic organisms on Earth, which created the primary atmosphere. Scientists believe that terrestrial plants originated from algae, which came to land even in the Paleozoic era. Algae are widely used in the national economy, primarily as food plants (kelp); from algae, alginic acid salts are obtained - alginates, which are necessary in the production of ice cream, fruit juices, canned food, plastics, varnishes and paints; in the processing of algae, a six-atomic alcohol is obtained - mannitol, which is used in the treatment of diabetes, for the dressing of leather and paper (once it was also used in the manufacture of explosives); agar and carrageenans are extracted from algae, the latter are used in medicine as inhibitors that suppress the growth of the AIDS virus; some algae are used to extract iodine from them. Many algae are an important link in the biological treatment of wastewater. Algae living in the soil increase its fertility. The science of algae is called algology.

Among the most important departments is the GREEN ALGAE department, representatives: unicellular algae - chlamydomonas and chlorella; colonial algae - volvox and pandorina; filamentous multicellular algae - spirogyra, hara. The main feature of the representatives of this department is reflected in the name - they all contain the same pigments as higher plants - chlorophylls.

The department of BROWN ALGAE is represented mainly by the inhabitants of the sea, which have thalli from a few centimeters to 50 m long, the brown color of which is due to xanthophyll pigments. Among them is the well-known kelp kelp (seaweed), macrocystis, fucus and sargassum (growing off the coast of America).

The DIATOM ALGAE department is represented mostly by unicellular, living in small colonies and being part of plankton, which is the main food for fish and a number of crustaceans. The cells of diatoms are covered on the outside with a hard shell, consisting of two halves, including silicon dioxide. Mass accumulations valves of diatoms form a rock - diatomite. Previously, impregnating diatomaceous earth with nitroglycerin, they obtained explosives - dynamite. Today, diatomites are used in construction and the chemical industry.

The department RED ALGAE, or PURPLE, includes mostly multicellular, deep-sea (up to 100 m) species. The color of algae is due to a combination of several pigments: chlorophyll, phycoerythrin, phycocyan. The most famous red algae is porphyry, which is used as food by the inhabitants of the Pacific coast, for this it is specially grown on marine farms off the coast of Japan and Korea.

Rice. 57. Phylogenetic tree of the animal world, built in accordance with evolutionary theory. The fossil record contains little information about the relationships between the groups represented here, because the first invertebrates, devoid of solid structures, are poorly preserved. The theory reflected in this scheme was created mainly on the basis of data on the structure and embryonic development of modern animals. Closely related animals usually have similar embryonic development.

Invertebrates include all representatives of the sub-kingdom unicellular: Sarcomastigophores (Rhizoflagellates); spores; Knidosporidia; Microsporidia; ciliates etc. - a total of 7 types, and 17 types of the multicellular subkingdom, 6-8 of them are studied at school: Sponges; Coelenterates; flatworms; Roundworms (primary worms); annelids; Arthropods; Mollusks (soft-bodied); Echinoderms. Vertebrate zoology combines all the information in only one type of multicellular animals - chordates.

All the types listed above can be combined under one name - SIMPLE. At the moment, there are about 40 thousand species of these animals. Compared to other types, Protozoa have become known only recently, since the invention of the microscope. The first descriptions of the Protozoa date back to the second half of the 17th century.

The very concept of "Protozoa" was formulated only in the 19th century. Kölliker and Siebold. Many protozoa, such as foraminifera, played an important role in the formation of sedimentary rocks (limestones and chalks) that are widely used today in the construction industry. The science that studies protozoa is called protozoology.

First multicellular animals apparently descended from colonial flagellates. Remains of multicellular organisms (coelenterates, worms) are found in Precambrian deposits. Multicellular invertebrates lived in water, had a small body size, which was a cooperation of specialized cells.

Some invertebrates led an attached way of life, like representatives of the Sponge type. Now there are about 5 thousand species of sponges on Earth. Sponges look like small “bags” or “mittens”, with their mouth facing the surface of the reservoir. The inner cavity of sponges is lined with a layer of flagellar cells - choanocytes, involved in the process of food capture and digestion during passive nutrition (water, along with bacteria, blue-green algae, protozoa, enters the internal cavity through the pores and channels in the body of the sponge and exits through the mouth - all solid particles of food are retained by choanocytes) . The surface layer of the sponge is formed by squamous epithelium. Between the layers there is a structureless mass - mesoglea With inclusions in the form of silicon or lime needles (spikul), acting as a skeleton. Most sponges are hermaphrodites. A larva develops from the egg, which emerges from the body of the sponge, swims for some time, then settles to the bottom and gives rise to a new sponge. Sponges are able to reproduce vegetatively by budding. Some sponges are used in medicine, cosmetology and for technical purposes. In natural cenoses, sponges act as filter feeders. Lots of freshwater sponges lives in Lake Baikal, perhaps this is partly due to the purity of its water. Among the sponges in temperate latitudes, the bodyaga sponge is the most famous.

The type of INTEL combines about 9 thousand species that lead an exclusively aquatic lifestyle. Among the coelenterates, there are both free-living representatives and species attached to the substrate. Coelenterates are characterized by radial symmetry and a two-layer structure. In the simplest case, the body of the coelenterates has the appearance of an open bag at one end. Digestion of food takes place in the cavity of the sac, and the opening of the sac is the mouth. In addition to intracavitary digestion, there is intracellular. Remains of undigested food are removed through the mouth. The sessile forms of coelenterates are called polyps, free-floating - jellyfish. The division into polyps and jellyfish is not systematic, but morphological, the fact is that at different stages of the life cycle the same type of coelenterates has the structure of either a polyp or a jellyfish. Many polyps lead a colonial lifestyle (coral polyps). The characteristic features of representatives of the type include the presence of stinging and epithelial-muscular cells. The type has three classes: hydroid polyps(representatives: hydra, tubularia, obelia); Scyphoid polyps and jellyfish(Aurelia, cyanide, cornerot); coral polyps(madrepore corals, sea anemones - non-skeletal corals). Coral polyps do not have a jellyfish stage, but symbionts often settle in their body - unicellular algae zooxanthella, which supply organic compounds and calcium carbonate for the skeleton to corals. As a result of the vital activity of corals, reefs (coastal, barrier and atolls) are formed. Reefs serve as a habitat for many marine animals, algae, molluscs, worms, crustaceans, echinoderms and other inhabitants of the bottom settle here in large numbers - a unique ecosystem is created.

The type ANELLATED worms unites about 9 thousand species of segmented secondary cavities, with a body size from several millimeters to 3 m. dorsal - connected by transverse vessels forming "hearts"), segmented paired proto- or metanephridia, skin (sometimes gill) respiration. The nervous system consists of the "brain" and the nerve chain. There are sense organs: eyes, olfactory pits, balance organs, tentacles. Annelids are dioecious or hermaphrodites. Development is direct or with a trochophore larva (in primitive marine worms). They live in the seas, fresh waters, on land. In the type of annelids, three classes are distinguished: MULTI-BRISTLE(nereis, peskozhil); SMALL Bristles(tubifex, earthworm); leeches(medical leech, large false horse leech). The value of annelids in ecosystems is extremely high. Polychaetes are excellent food for fish and crustaceans. The earthworm is involved in the process of soil formation (moving in the soil, the worm, as it were, passes it through itself, thereby fertilizing and loosening the substrate). Leeches are used in medicine (leech saliva contains the protein hirudin, which prevents blood clotting, it stops the development of blood clots in blood vessels and is useful for hypertension).

The phylum Arthropoda is the largest phylum in the kingdom Animals, with more than 1.5 million species. The main features of the type are the following: heteronomous segmentation of the body (the head, chest and abdomen are distinguished; although in some species the segments may merge); limbs movably connected to the body; the presence of a chitinous cuticle, which forms the external skeleton of arthropods; the musculature is represented by separate muscle bundles - muscles; there is a mixed body cavity, or mixocoel. The digestive system of arthropods consists of three sections: the anterior, middle and hindgut. Digestive glands appear that secrete digestive enzymes. The circulatory system is characterized by the appearance of a central pulsating organ - the heart, at the same time the circulatory system becomes open again, the circulating fluid in it is the hemolymph, which flows from the arteries into the body cavity, washes internal organs and re-enters the blood vessels and heart. The respiratory organs of arthropods are diverse. In aquatic inhabitants, these are gills; land dwellers have "lungs" and special respiratory tubes - tracheas. Gills and "lungs" in evolutionary terms are nothing more than modified limbs. The nervous system is similar to that of annelids, but there is a large concentration of nerve ganglia in the head and thoracic regions, which, merging, form nerve nodes. The sense organs are well developed: in addition to simple eyes, there are complex faceted ones, consisting of many small eyes, which gives a mosaic image of objects. The organs of touch are well developed. The excretory system of arthropods is represented by special coxal glands and malpighian vessels. Arthropods have only a sexual mode of reproduction, and they, as a rule, have separate sexes, sometimes with pronounced sexual dimorphism. In most representatives of the type, development is accompanied by molting. The type has three classes: Crustaceans (20000 species), arachnids (350,000 species) and Insects (1,000,000 species).

Class INSECTS belongs to the Tracheal subtype and is characterized by the division of the body into the head, chest and abdomen; the presence of three pairs of limbs, only on the head and chest; diverse mouthparts: gnawing, lacquering, piercing-sucking, licking. The mouth apparatus is created by the upper jaws - mandibles and lower jaws maxillas. In bees and bumblebees, which have lacquering mouthparts, the mandibles are used to collect and grind solid flower pollen, and the maxilla are used to suck up nectar. The presence of wings determines the possibility of flight (in most cases there are two pairs of them). The class Insects includes all tracheal-breathing arthropods that have Malpighian vessels as excretory organs. Malpighian vessels are tubes that open at one end into the body cavity, and at the other into the hindgut. Metabolic products from the hemolymph in the form of uric acid enter the Malpighian vessels, and then, in the form of uric acid crystals, together with undigested food residues, are removed through the anus to the outside. Excretory functions can also be played by the fat body (loose tissue in which both uric acid crystals and nutrients can be deposited). Due to the presence of a fatty body, insects can starve for a long time without losing the ability to actively live (bugs and cockroaches up to 6 months). Insects have superbly developed vision, touch and smell (male Artemis butterflies arrive at the smell of a female for 11 km). Almost all insects have separate sexes.

Today, the Insect class is subdivided into more than 30 orders, among which the following are the most important. Coleoptera (beetles) - May beetle, ground beetle, weevil, ladybug, dung beetle, Colorado potato beetle. They have rigid anterior and membranous hindwings, the anterior (elytra) covering the hindwings. Mouth organs are gnawing. Develop with complete transformation. Detachment Lepidoptera (butterflies) - cabbage, urticaria, swallowtail, peacock eye, mother-of-pearl. Butterflies have two pairs of scaly wings (scales are modified chitinous hairs). The oral apparatus is a sucking proboscis, coiled. They develop with complete transformation (the larvae develop a gnawing type of mouth apparatus). Detachment Hymenoptera- ants, wasps, bumblebees, bees, sawflies, riders. They have two pairs of membranous transparent wings, gnawing or licking mouthparts. In females, an ovipositor is located at the end of the abdomen, in bees and bumblebees it is modified into a stinger. Development with complete transformation. In some Hymenoptera, the larvae develop in pupae or in the larvae of other insects. Detachment Diptera- flies, mosquitoes, horseflies. Representatives of the order have one pair of membranous wings and licking or piercing-sucking mouthparts. Development with complete transformation. Detachment Orthoptera- grasshoppers, locusts, bears. Orthopterans have developed front wings with longitudinal venation, hind wings are fan-shaped; chewing mouthparts. incomplete transformation. Detachment bedbugs includes species with two pairs of wings and piercing-sucking mouthparts. Development with incomplete transformation. Representatives: forest, berry, bed bugs. Detachment Homoptera- aphid, copperhead. Insects have two pairs of transparent wings and mouthparts in the form of a piercing-sucking proboscis. Homoptera have development with incomplete metamorphosis. A significant part of insects arose and evolved in parallel with flowering plants. The science of insects is called Entomology. Unfortunately, insect biodiversity is declining today. About 200 species are listed in the Red Book of Russia, of which 34 species are in the Red Book of the Middle Urals.

Type mollusks (soft-bodied) - invertebrate secondary cavities, which arose presumably in the Precambrian from worm-like ancestors. Distributed throughout the globe. Most live in the seas, although molluscs are found in freshwater and on land. Introductory inhabitants mainly lead a bottom lifestyle and are divided into burrowing, attached to the substrate and crawling; detritivores, predators and herbivorous scrapers. In total, there are about 130 thousand species of mollusks on Earth. TO characteristic features types include the following: the body is divided into three sections - the head (in sedentary forms, the head can be reduced), the trunk and leg (the leg is an outgrowth of the abdominal wall of the body on which the mollusk crawls); available mantle- outer skin fold covering the body; aquatic representatives of the type breathe with the help of gills, in land species a lung appears; from above, the body of the mollusk carries a protective shell, mainly of calcium carbonate, which is a derivative of the mantle (floating mollusks have lost their shell); for crushing food in molluscs occurs radula- horny hook-shaped outgrowths of the walls of the pharynx; the circulatory system is open and consists of the heart (subdivided into atria and ventricles), aorta, arteries, lacunae (gaps between organs where blood flows) and veins; a large digestive gland appears - the liver.

cephalopods mollusks unite about 650 species leading an active lifestyle and the most highly organized invertebrates. The leg of the mollusks turned into a crown of tentacles on the head. From the shell there was a rudiment, immersed in the mantle and similar to narrow cartilage. All cephalopods are predators. Mollusks have a brain (several contiguous ganglia, forming a single nerve mass enclosed in a cartilaginous skull). The body has a special device - the "ink" gland, the secretions of which are poisonous and paralyze the olfactory nerves of predatory fish. Cephalopods are dioecious. Most of them have pronounced sexual dimorphism (males are usually smaller than females). Among the representatives: squid, octopus, cuttlefish. Almost all cephalopods are the object of fishing; in terms of nutritional value, squid meat is not inferior to beef.

Representatives of the echinoderm type (sea lilies, starfish, serpentine brittle stars, sea ​​urchins) belong to a large group of animals united under the common name SECOROTOMS. In all representatives of the types of Invertebrates (primary-stomes) considered earlier, the oral opening existed in the place of the larval mouth, in deuterostomes, an anus appears in this place, and the mouth breaks through again. The secondary body cavity in echinoderms is the coelom, but it is formed not from the cells lying near the intestine (as in protostomes), but directly from the protrusions of the larvae's intestines themselves, which then detach from it. Echinoderms arose in the Precambrian, and although most of them died out in the Paleozoic, today about 5 thousand species of these invertebrates live in the seas and oceans of the planet. According to the plan of the structure, they differ sharply from all other animals. Echinoderms are characterized by radial symmetry, most often five-rayed. Among echinoderms, there are both sessile and mobile species. They vary greatly in body shape, can be stellate and spherical; disc-shaped and capsule-shaped; worm-like and flower-like. Body sizes range from a few centimeters to 1 m (some fossil crinoids were up to 20 m in length). Most echinoderms develop a skeleton of calcareous plates with spines under the skin that can protrude outwards. The mouth is located in the center of the body. The specificity of echinoderms is the presence of ambulacral system(water-vascular), through it there is gas exchange and excretion, it also promotes movement. There is a circulatory system. There are no special excretory organs. The nervous system is not developed (consists of radial nerve cords). The intestine is represented by a tube or, in some species, a sac-like formation. Echinoderms are dioecious (rarely hermaphrodites), fertilization is external; the bilaterally symmetrical larva swims for a long time and undergoes metamorphosis. Echinoderms are divided into three subtypes and five classes. Echinoderms differ in the mode of feeding: among them there are detritophages, predators and herbivorous forms. In turn, the echinoderms themselves are food for bottom fish. Some species are used by man as an object of fishing, these are sea urchins and sea cucumbers (sea cucumbers) - cucumaria and trepang.

The Chordata type is represented by 43 thousand species of modern deuterostomes with a skeleton in the form of a notochord lying above the gut. Very often, chordates are called the highest type among animals, since they include the most famous representatives Animal kingdoms: fish and amphibians, reptiles and birds, mammals, including humans. Appearance chordates is very diverse - from immobile saccidian ascidians to vertebrates of various shapes. The size of chordates also varies: from a few millimeters or centimeters (larvae of frogs - tadpoles) to 30 m and 150 tons (some whales). The position of chordates in the system of the animal world is quite isolated. The following common features of the organization of chordates are not found in representatives of other types: 1) there is a chord - a dorsal string that performs the functions of an internal skeleton (in some species, the chord does not exist throughout life, but only at certain phases of development), in most animal species during ontogenesis the notochord is replaced by the spine; 2) the central nervous system has the form of a tube lying above the chord; in vertebrates, it is differentiated into two sections: the brain and spinal cord; 3) the anterior part of the digestive tube - the pharynx - is pierced by gill openings that open outward and performs two functions: parts of the digestive tract and the respiratory organ, and in aquatic vertebrates derivatives of the pharynx develop - specialized respiratory organs - gills, and in land animals - lungs; 4) throughout the ontogenesis and phylogenesis, an increasingly complex muscular organ functions in the circulatory system - the heart, which is located on the ventral side of the body, under the notochord and digestive tube. Chordates are characterized by bilateral (bilateral) symmetry: only one plane of symmetry can be drawn through the body, dividing it into two halves, which are, as it were, a mirror image of each other. It is believed that the ancestors of the chordates were some kind of annelids (polychaetes), which switched to an active lifestyle. The transition of primitive chordates to a new habitat - from the sea to freshwater bodies and to land - apparently contributed to the development of the motor system, the intensification of metabolism, the improvement of the nervous system and sensory organs, which in turn was accompanied by a complication of behavior and the emergence of various forms of communication.

The phylum Chordates is subdivided into three subtypes: Cephalo-Chordates (Cranianless), Tunicates (Larval-Chordidae), Vertebrates (Cranial) and 15 grades. In modern fauna, chordates occupy only 3% of total number animal species, but their importance is enormous, especially in ecosystems where chordates are the final links in food chains (consumers). The role of chordates (especially vertebrates) is also great in human life. Among domesticated species, they make up 80%. The fishing of fish, birds and mammals is one of the areas of human activity, providing it with animal protein and raw materials for medicine and industry (tanning, textile, etc.). There are many pests among chordates Agriculture and carriers of pathogens of infectious diseases (mouse-like rodents, pigeons, etc.).

cephalochordates live in many seas of the globe, lead a bottom lifestyle. The shape resembles small fish from a few millimeters to 6-8 cm long. There are about 35 species of lancelets in the subtype. The name is determined by the fact that the tail fin of animals is similar to a medical surgical knife - a lancet. Lancelets retain all the features of the Chordata type: there is an internal skeleton (chord) and a nervous system in the form of a tube; the pharynx is perforated by numerous gill slits and serves as a respiratory organ, there is a hepatic outgrowth in the digestive tube, and the circulatory system is closed.

hullers are the most deviated branch of chordates, developing along the path of morphological regression. Typical signs of chordates are presented in them only in the larval stage. Tunicates live in the seas and either lead a sedentary lifestyle or move slowly in the water column. The body is covered with a shell, or tunic. Under the tunic lies the mantle, or skin-muscle bag. The tunicates are passively fed by filtering large amounts of water. Almost all are hermaphrodites, some, in addition, are able to reproduce by budding. The primitive features of the organization include the presence of an open circulatory system. Among the representatives of the subtype, ascidia and appendicularia are most known. In appearance, the sea squirts resemble a two-necked jar, attached by the base to the substrate and having two openings - siphons: oral and cloacal. Ascidians often lead a colonial way of life, so, in the tropics, up to 10 thousand individuals with a total weight of up to 140 kg can settle per 1 m 2. Appendicularia are represented by small (up to 2 cm) swimming animals, similar to rounded fish in transparent houses made of mucus containing chitin-like substances. The shape of the house is different, but always in its front part there is a cone-shaped "trapping net" of thin mucous threads, and in the back of the house there is an outlet. The constant work of the appendicular tail creates a current of water that is sucked through the net and thrown out with force from the rear opening of the house, thereby giving the animal the ability to jet locomotion.

More highly organized chordates belong to the subphylum VERTEBRATES, or CRANIAL. They are distinguished by an active lifestyle, due to the search for food on land, in connection with which the motor system is being rebuilt. The notochord is replaced by the spine; a skull develops armed with jaws; paired limbs and their belts appear. New excretory organs appear - the kidneys, which are able to save water as much as possible when removing metabolic products from the body. The structure and functions of the nervous system and sense organs become more complicated; improved humoral regulation. On this basis, behavior is diversified. There is concern for offspring. Vertebrates are known from the Ordovician and Silurian. Modern vertebrates are divided into seven classes: Cyclostomes, Cartilaginous fishes, Bony fishes, Amphibians (Amphibians), Reptiles (Reptiles), Birds and Mammals (Beasts).

All other chordates are classified as Jaws. FISHES - the most ancient primary aquatic jawed vertebrates, capable of living only in water. In the modern fauna there are about 22 thousand species of fish distributed in all water bodies of the globe (some fish, such as African lungfish, are able to live without water for some time). Among the fish there are real babies (goby, blenny), whose adult size does not exceed 1.5 cm, and there are giants (whale shark, beluga, stingray), whose parameters are from 5 to 20 m in length and weigh several tons. Fish dominate in aquatic biocenoses due to the peculiarities of their external and internal structure. The excellent abilities of swimmers depend on the presence of paired pectoral and ventral fins; torpedo-shaped body covered with scales; as well as a fairly well-developed brain and sensory organs (lateral line organs arise). The relative weightlessness of fish is achieved in two ways. The first one is presented by cartilaginous fish and lies in the accumulation of fat reserves in the liver and less often in other tissues of the body (in sharks, the mass of the liver is 14-25% of the total body weight). The second one is expressed in bone fish, they have a special hydrostatic organ - swim bladder, filled with air. The digestive tract in fish is differentiated into the stomach and intestines, consisting of two sections: thin and thick. Fish breathe with gills. They have one circulation. The circulatory system is closed. The heart consists of the venous sinus, atrium, ventricle and arterial cone. The excretory system of fish is represented by the middle kidney - two ribbons on the sides of the spine. Urine is collected in paired ureters, which open with a common opening into the cloaca, and the ducts of the sex glands can also open there. As a rule, maxillostomes are dioecious. Fertilization is external or internal. According to their habitats, marine and freshwater fish are distinguished. There is a group of migratory fish that spend part of their lives, usually during spawning, in rivers and lakes, and the rest of the time they live in the sea (salmon). There are fish that, on the contrary, go to the sea for the breeding season (eels). Fish are deep-sea (armored pike, rays, flounder); some are able to live in the surface layers of water (anchovy); some of them lead a flock of life (scad), others live in pairs (during the breeding season - stickleback) or singly (shark). Fish can be diurnal and nocturnal. They may have a protective coloration and mechanical (thorns, spikes, needles) or electrical means of protection. On average, the speed of movement of fish is 2-6 km, but good swimmers are able to develop it up to 30-40 km / h (blue shark), and when thrown at prey, the speed reaches 110-130 km / h (swordfish).

Class cartilaginous fish includes about 800 species. Among its representatives are mainly marine life. Modern forms have a cartilaginous skeleton. The skin is naked or supplied with placoid scales (bone plates covered with tooth enamel). There are 5-7 pairs of external gill slits. There is no swim bladder. Many species develop ovoviviparity or viviparity. The eggs are large, in a dense horn-like capsule. The living cartilaginous fish are divided into two subclasses: elasmobranchs and Whole-headed. Among the elasmobranchs, the most famous are sharks(250 species) and stingrays(340) species, and among whole-headed - chimeras(about 30 species).

In class KbST FISH about 20 thousand species, this is the most numerous class of chordates. Its representatives inhabit almost all water bodies of the globe. The internal skeleton is bony or cartilaginous, but with integumentary bones. The skin develops ganoid scales (coated with an enamel-like substance), or bony scales. Five pairs of gill slits are always covered by a gill cover. There is a swim bladder. In some species, a lung is present (in the form of an abdominal protrusion of the beginning of the esophagus). In most species, fertilization is external, i.e., the female spawns, and the male waters it with milk. Eggs (caviar) do not have a dense horn capsule. The class is divided into two subclasses: lobe-finned fish and Ray-finned fish. There are 5 orders of lobe-finned fish, including coelacanth, horntooth, protopterus and many others, rare, often deep-sea and, unfortunately, little-known fish. Ray-finned fish include 36-40 orders, and some of them are well known to everyone, since there are a lot of commercial fish among the representatives: sturgeons(beluga, kaluga, sturgeon, stellate sturgeon, sterlet, spike); herring(herring, sprat, anchovy, or anchovy); salmon(pink salmon, chum salmon, chinook, salmon, nelma, taimen, whitefish, omul, muksun, trout); eels(eel, moray eels); Cypriniformes(carp, carp, bream, roach, silver carp); Codfish(cod, haddock, pollock, hake, navaga, burbot); Perciformes(perch, swordfish, tuna, pike perch, gobies, horse mackerel, mackerel, catfish). All of the listed orders, with the exception of sturgeons, belong to bony fish. By the way, many of them were subjected to selection and today are bred artificially on fishing farms and factories (mirror carp) or kept in aquariums (macropods, bettas, gourami, scalars). The work on fish acclimatization is going on successfully, for example, pink salmon is inhabited in the rivers of the Murmansk coast of the Barents Sea; carp and whitefish - in the lakes of the Trans-Urals.

The first and most primitive vertebrate inhabitants of the land are considered amphibians, or AMPHIBIA. There are about 4000 species in total. Amphibians in their ontogeny are closely related to water, since they cannot do without it either at the larval stage (tadpoles develop in water) or in the adult state. Amphibians originated from ancient lobe-finned fish in the Devonian and occupy an "intermediate" position between fish and real land inhabitants. The sizes of amphibians range from 2-3 cm to 1.8 m in adulthood. The features of amphibians should include mainly cartilaginous skeleton; moving head; the appearance of two pairs of five-fingered limbs with articulated joints; the formation of limb belts, characteristic of structural features for all subsequent vertebrates; the absence of the chest (in the presence of short ribs), which ensures the swallowing of air; a large number of skin glands; the presence of sac-like or cellular paired lungs (gills are present only at the larval stage of development); the appearance of a three-chambered heart (two atria and one ventricle); division of the forebrain into hemispheres; adaptation of the eyes to vision in the air (eyelids and nictitating membrane appear); development of the middle ear, covered by a membrane - the tympanic membrane.

All amphibians are predators. They feed mainly on insects. They have a fairly primitive digestive system, which ends with the rectum, which flows into the cloaca, where the ducts of the ureters and bladder open. In the body of amphibians are the liver and pancreas, as well as paired kidneys - mesonephros. Amphibians have separate sexes, fertilization is mainly external. The development of the egg occurs in the water, in the same place a larva emerges from it - a tadpole with gills, a "fish" tail and a two-chambered heart. After the metamorphosis, during which the gills are resorbed, the heart changes, the laying of the limbs, the change of nutrition from herbivorous to predatory, the young amphibian comes to land. The body temperature of amphibians depends on the ambient temperature and only slightly exceeds the latter (poikilothermia). Adult amphibians lead a solitary life, forming aggregations only for the breeding season, during wintering and during migrations. Many species of amphibians are able to make sounds during spawning, which help other individuals navigate the terrain. Amphibians spend the unfavorable period of the year in a daze. The duration of wintering in the temperate zones can be up to 230-250 days. Amphibians (lake and grass frogs) winter in water bodies, gathering in groups in deeper, non-freezing areas. Toads, tree frogs, newts are able to winter on land, climbing into rodent burrows, under stones and snags. When body temperature drops below 0.5-1 degrees, amphibians die. Most species of amphibians live off the coast of water bodies in the temperate zone, as well as in the tropics and subtropics. Some were able to populate reservoirs (proteas, sirens, clawed frogs). Some species have switched to an arboreal way of life (tree frogs). And several species were able to master desert habitats (green toad). The Siberian salamander, common and Siberian frogs penetrated the Arctic Circle. Amphibians are an important link in ecosystems. Feeding on insects, they themselves enter the diet of fish (tadpoles), reptiles, birds and mammals. In a number of countries, salamanders and frogs are used by humans for food. They are also widely used in medicine as laboratory animals.

In modern taxonomy, the Amphibian class is subdivided into 11 orders, the bulk of the representatives of which have come down to us in the form of paleontological finds. In three teams: Tailless, Tailed and legless, representatives of which now inhabit the planet, there are 2500 species. Detachment tailless unites 2100 species distributed all over the world: these are toads, toads, tree frogs, frogs, spadefoot. Detachment Tailed has a total of 280 living species, in which the head imperceptibly passes into an elongated body and always has a tail, and the limbs are poorly developed: cryptogills, salamanders and frogtooths, sirens and proteas, salamanders. To the squad legless include species that resemble long worms or snakes (up to 120 cm), they have no limbs, the body is divided into separate “segments”, there are bone scales in the skin; most representatives lead an underground lifestyle (worms). Some species of amphibians are now under threat of extinction due to pollution of water bodies. In the Ural region, seven species are listed in the Red Book: Siberian salamander, crested newt, red-bellied toad, common spadefoot, green toad, as well as Siberian and lake frogs.

reptiles, or REPTILES, - the first class of true terrestrial vertebrates. The oldest reptiles - cotylosaurs - appeared in the Carboniferous. Among reptiles, terrestrial inhabitants predominate (although there are also secondary aquatic animals). In total there are 8000 species of reptiles. Body sizes from a few centimeters to 10 m. Reptiles live on all continents except Antarctica. The general level of vital activity of reptiles is much higher than that of amphibians. Among the features of the class, the following are distinguished: the skin is dry, almost devoid of glands; horny scales and scutes form in the skin; breathing is only pulmonary, and airways are formed - trachea and bronchi; air is sucked into the body, including due to the appearance of the chest; three-chambered heart (crocodiles have four-chambered); two circles of blood circulation; metanephric (pelvic) kidneys; a number of species have a bladder; more large sizes brain (large hemispheres and cerebellum increase); the skeleton is ossified. The body temperature of reptiles is not constant, it depends on fluctuations in the ambient temperature (poikilothermia). Reptiles have separate sexes, their fertilization is internal. Most reproduce by laying eggs, some are oviparous or viviparous. The egg is covered with a hard lime or parchment-like shell that protects it from drying out. Predators and insectivorous species predominate among reptiles, some are herbivorous (turtles). In modern taxonomy, the class of Reptiles is divided into 17 orders, of which today living representatives are combined into 4 orders. The remaining 13 orders are paleontological finds of a previously flourishing group that dominated throughout the Mesozoic era (diplodocus, stegosaurs, cotylosaurs, ichthyosaurs, plesiosaurs, etc.).

The modern fauna of Reptiles includes the following taxa: detachment Turtles (about 200 species), animals with a shell covered with horny shields or skin (in soft-skinned turtles); detachment beak-headed With the only representative of the hatteria, or tuatara (inhabits the islands of New Zealand); detachment scaly (6100 species), among the representatives: chameleons, lizards (geckos, iguanas, agamas, skinks, spindles, monitor lizards, poisonous teeth and real lizards), snakes (boas, pythons, cobras, snakes, vipers, etc.); and squad crocodiles (alligators and real crocodiles). The body shape of reptiles is extremely diverse. In the course of evolution, snakes lost their limbs and switched to reptiles (average speed of movement is 5 - 8 km / h). Many reptiles developed specialized defense organs, such as grooved and tubular teeth, which introduce the secret of poisonous glands into the body of the victim. Snake venom consists of a mixture of proteins and enzymes that tend to break down prey proteins and promote blood clotting of prey (vipers and pit vipers); or from neurotoxins that paralyze the nervous system of the victim (aspid and sea snakes). The complication of the structure of the brain went in parallel with the complication of the sense organs, behavior and orientation of animals in space. The population organization of reptiles is also more complex than that of amphibians. Most reptiles lead a solitary lifestyle, but this does not exclude constant communication with neighbors. As a result, group ties are established and a certain system arises in the use of the territory. For example, among chameleons, each adult male has his own territory, from which other mature males are expelled, but on which several females are allowed to live. The territorial areas of reptiles are often heterogeneous and consist of a center of activity and a periphery where meetings with neighbors are possible. In some cases, the sites are adapted by the owners: a system of trails, shelters and shelters is created. In addition to active protection, reptiles use chemical marks, sound signals, and ritual postures to defend the site. Some reptiles tend to form clusters during the breeding season and take care of the condition of the eggs until the offspring appear (incubate, turn over, etc.). The duration of the active period in the life of reptiles of temperate latitudes depends on the ambient temperature and is approximately five months a year. Reptiles hibernate in rodent burrows, under stones and snags. From wintering places, reptiles can migrate for short intervals - up to 1-2 km (viper) or over long distances - up to 2000 km (green turtle). In biogeocenoses, reptiles participate in the circulation of substances, being a link in food chains, and also perform the function of soil rippers, especially along the banks of the reservoirs in which (alligators) live. Reptiles destroy harmful insects; poison is extracted from them for the manufacture of therapeutic serums, against bites and for the creation of valuable drugs based on it that relieve pain in diseases such as rheumatism, osteochondrosis, bronchial asthma, neuralgia, etc. Turtle shells, crocodile skin and snakes were used earlier, and on a smaller scale, they are now used for the manufacture of jewelry and leather products. Due to environmental pollution and uncontrolled fishing, some species of reptiles have drastically reduced their numbers and are on the verge of extinction, many of them are listed in the Red Book. In the Urals, there are three types of reptiles under protection: the brittle spindle, the nimble lizard and the copperhead.

To the class BIRD include vertebrates covered with feathers with a constant body temperature (homeothermic), whose forelimbs have turned into wings. The ability to fly in some birds was lost a second time (penguins, ostriches), but they have the ability to quickly run, walk, swim and dive. According to a number of anatomical and morphological features, birds are similar to reptiles. In fact, even in the Triassic, a branch of archosaurs separated from the ancient reptiles. Primitive archosaurs - pseudosuchians then, in the Triassic, gave rise to crocodiles, various dinosaurs and flying lizards. Birds separated from some small pseudosuchia, and this happened about 190-170 million years ago. During the reign of reptiles, birds were forced to populate the least suitable for life areas of the Earth, not yet mastered by reptiles and amphibians. Many changes in the skeleton, external integuments, internal organs and their systems that arose during evolution, warm-bloodedness allowed them to do this. Transformations in the central nervous system entailed a complication of behavioral reactions that gave an advantage in the struggle for existence and contributed to the growth of numbers, the emergence of new species, and the spread of birds in the biosphere. Now in the class of Birds there are 9000 species, divided into 2 subclasses and 34 orders, including 28 of them are modern and unite about 8600 species of birds living now.

In the 1st subclass lizardtail, or ANCIENTS, BIRDS, only one fossil bird is included - Archeopteryx, the remains of which were found in shale sandstones - deposits of a shallow bay of the Jurassic Sea. Five skeletal impressions and feather impressions were found of a lizard-like feathered creature with a long tail, overall the size of a dove. The age of the prints was 150 million years. In the 2nd subclass fantail,--or REAL, BIRDS, includes all other orders, uniting both modern and extinct birds (epiornis, moas). Once upon a time, birds lived on Earth, the mass of which exceeded 400 kg, today the maximum body weight of the largest birds does not exceed 100 kg (African ostrich). The smallest birds have a weight of 1.6 g to 20 g (hummingbirds, song sparrows - honey plants and nectaries). The average body weight of modern birds ranges from 50 g to 1 kg. The characteristic features of the class include: a streamlined body; moving head; the presence of plumage and modified limbs - wings; dry, almost glandless skin (there is a coccygeal gland that produces a fat-like secret with which birds lubricate their wings, which contributes to their elasticity and non-wetting with water); the presence of horny scales on the hind limbs; horny beak; pneumatization of bones; an increase in the cerebellum (contributed to better orientation in space) and the total mass of the brain; intensification of vision (larger than the visual lobes of the midbrain) and hearing; the formation of a system of air sacs (in addition to the lungs); a four-chambered chambered heart and complete separation of the large and small circles of blood circulation (contributed to a better supply of oxygen and nutrients to tissues and faster removal of CO 2 and decay products from the body), homoiothermy (helped to increase the resistance of birds to fluctuations in ambient temperature). The incubation of eggs by birds and the care of offspring through the feeding of chicks contributed to the reduction of their mortality in the early stages of ontogenesis.

Warm-bloodedness and high mobility of birds are provided by the consumption of a large amount of food. Most birds are insectivorous, there are herbivorous birds and predators (eating fish, amphibians, reptiles, birds smaller than themselves, and mammals). There are omnivorous species. The digestive system of birds is somewhat different from that of reptiles: a goiter appears - a temporary receptacle for food; the stomach is divided into two sections - glandular (digestive enzymes are abundantly secreted in it) and muscular (food is ground in it); the intestine is elongated and more differentiated. The intensity of digestion in birds is very high, so a sparrow spends 20 minutes to completely digest a caterpillar, and a hawk with a body weight of 1.5 kg can eat up to 1 kg of food at a time.

The respiratory surface of the lungs of birds is larger than that of reptiles, in addition, air sacs are associated with them, the volume of which, in turn, is 10 times the volume of the lungs. Air sacs are located between organs, and some are even able to go under the skin or penetrate into the cavities of large bones. Oxygenated air, both during inhalation and exhalation, is constantly in the respiratory system, being pumped from the lungs into the air sacs (when the bird raises its wings, the sacs expand and fill with air from the lungs; when the wings are lowered, the sacs are compressed, and the air, leaving them, blows through the lungs at the exit for the second time), - this is extremely necessary for birds, especially in flight, when the frequency of respiratory movements increases, the blood still has time to clear itself of carbon dioxide and be saturated with oxygen.

A characteristic feature of birds is the relatively large size of the heart (up to 2% of body weight), divided into two atria and two ventricles. The pulse in birds is up to 300 beats per minute at rest and up to 500 in flight. Blood pressure reaches 200 mm Hg. Art. Excretion is carried out through paired metanephric kidneys, however, birds do not have a bladder. The end product of excretion is uric acid, which is excreted through the cloaca in the form of a white mushy mass. Compared with reptiles, birds also undergo changes in the area of ​​the musculoskeletal system. The body skeleton is inactive and forms a rigid structure. The sternum bone turns into a keel, to which powerful wing muscles are attached, thanks to which birds are able to reach a flight speed of up to 160 km / h (black swift).

Birds, like reptiles, are egg-laying animals. They are dioecious, with internal fertilization. In females, only the left ovary develops, the reduction of the right one is determined by the fact that the simultaneous formation of eggs in paired ovaries is impossible. The outer shell of the egg is a dense calcareous shell. In the smallest birds, the egg weight is 0.2 g, and in the largest - up to 1.5 kg. The clutch can be from 1 egg (penguin, large birds of prey) to 22 (grey partridge and quail). Incubation lasts from 12 to 80 days. Reproduction in birds of temperate latitudes falls on the period of spring, early summer. Almost all birds have pronounced sexual dimorphism (more often males are larger than females and more brightly colored). Birds are divided into monogamous(for the breeding season they form a pair, and in some species the pair lasts for several years) - swans, eagles, herons, geese; and polygamous(pairs do not form, usually there are always several sexual partners) - capercaillie, black grouse, peacocks, hummingbirds. Reproduction in birds is accompanied by mating games and current (song). The current facilitates the meeting of the male and female, promotes the formation of a pair. During the current period, the nest is usually built. Birds are also divided into chicks(chicks appear blind and stay in the nest for a long time) and brood(they hatch sighted, able to feed on their own).

The population organization of birds is more complex and diverse than that of reptiles. Birds have their own nesting and feeding territory, are capable of mass migrations (flights), form flocks. Packs are characterized by a special organization, according to the formula: dominance - submission. According to habitats, several ecological groups of birds can be distinguished: tree-shrub birds; birds of open spaces; marsh; water birds. Birds have great importance in ecosystems, usually representing the final link in the food chain. They play an important role in plant pollination and seed dispersal. Birds of prey exterminate mouse-like rodents, which are carriers of dangerous pathogens of infectious diseases. Insectivorous birds protect the forest from pests. Many birds are commercial. Some have long been domesticated (turkeys, chickens, ducks). Unfortunately, birds themselves can be carriers of a number of viruses and bacteria that cause dangerous diseases (psittacosis, salmonellosis).

Of the most famous orders and genera of birds, the following stand out: order penguins(16 species inhabit Southern Hemisphere; do not fly, forelimbs modified into flippers; swim and dive; feed on fish) detachment African ostriches(1 species; the largest living bird; the ability to fly is lost; runs very well; leads a harem lifestyle; is bred by humans because of delicious meat); detachment Nandu-shaped(2 species living in South America, differ from African ostriches in smaller sizes); detachment Pelicans, or Veslondgie(50 species of pelicans leading a colonial way of life near large reservoirs; feed on fish; swim excellently; and 6 species of cormorants; fly and dive well, also feed on fish); detachment foliaceous, or ankle(various in size long-beaked, long-necked and long-legged birds; they fly in a soaring flight, in the air their outstretched legs protrude far beyond the tail: herons (60), storks (17), ibis (30), flamingos (6)); detachment Anseriformes (150 species of water birds: geese, swans, river ducks); detachment falconiformes, or Diurnal Birds of Prey (270 species of birds distributed throughout the globe; they have excellent flight abilities, a powerful, albeit short, curved beak: vultures, hawks, eagles, harriers, falcons); detachment Galliformes (250 species of terrestrial or terrestrial-arboreal birds of a characteristic chicken appearance; they feed on plant foods, to grind food they swallow stones that play the role of "millstones": weed chickens, capercaillie, black grouse, hazel grouse, partridges, pheasants, peacocks, quails, guinea fowls, turkeys) ; detachment Pigeons (300 species of mostly herbivorous birds: turtledove, pigeon); detachment owls (140 species of nocturnal birds of prey, with well-developed hearing, settling in hollows, feeding on mouse-like rodents and insects: owl, eagle owl); detachment passeriformes( 5,000 species of diverse birds building nests and caring for chicks until they fledge: sparrows, larks, swallows, crows, birds of paradise, tits, nuthatches, pikas, dippers, wrens, thrushes, warblers, flycatchers, wagtails, starlings, finches, crossbills, goldfinches, siskins, bullfinches). Due to the decrease in the areas of natural ecosystems caused by population growth, urbanization, environmental pollution, etc., biodiversity and bird numbers are declining. Measures are being taken for their reproduction: reserves and sanctuaries are being created, shooting of birds during nesting is prohibited, special decrees are issued to preserve rare and endangered species. To date, 19 species have been included in the Red Book of the Middle Urals, including the black stork, white-tailed eagle, golden eagle, peregrine falcon, red-throated goose, imperial eagle, whooper swan, marsh harrier, red-footed falcon, eagle owl, hawk owl.

MAMMALS - a class of vertebrates, homoio-thermal, viviparous, lactating animal cubs, with a body covered with hair. The class Mammals arose somewhat earlier than the class Birds from a group of primitive reptiles, the so-called animal-toothed reptiles (cynodonts) in the Triassic, approximately 215 million years ago. The first mammals, as well as birds, at the dawn of their existence, mastered the least adapted areas of land that were not occupied by Reptiles. A complex set of adaptations that arose by the Cenozoic era, determined physiologically and anatomically and morphologically, allowed mammals not only to survive, but also to occupy a dominant position among representatives of the terrestrial fauna. Today, various Animals, of which there are about 4000 species, are combined into 95 orders. The appearance and size of mammals are extremely diverse: from 4 cm long and 1.2 g in weight (shrew) to 4.5 m in height and 7.5 tons in weight (African elephant). Among the Mammals there are many secondary aquatic animals, among them there are real giants, for example: the blue whale, whose length is 33 m and weighs 150 tons. Among the main characteristics of the class Mammals are the following: a large brain (its anterior section has a "new cortex" - neopallium - from the gray medulla, which provides high level nervous activity and complex adaptive behavior). the organs of smell, vision, hearing are well developed (the outer ear appears and the middle ear is modified - it already contains three bones: the hammer, anvil and stirrup); some develop the ability to ultrasonic echolocation; the skin carries hair and a large number of glands, among which there are sweat, sebaceous and milk glands; only in mammals does saliva contain special enzymes that break down starch into monosaccharides; the lungs have an alveolar structure; a diaphragm appears, dividing the body cavity into the thoracic and abdominal sections; even more than in birds, the structure of the gastrointestinal tract becomes more complicated (in some species, the stomach becomes multi-chambered, undigested food residues are excreted through the anus); only the left aortic arch is preserved in the circulatory system (birds also have the right one); the larynx is well developed, vocal cords appear; cubs develop in the mother's body, receiving nutrition through the placenta, and after birth they are fed with milk. Mammals, like birds, have a constant body temperature that does not depend on fluctuations in ambient temperature, there is a four-chambered heart and metanephric kidneys, and the bladder reappears. The most important thing is that it is not individual, even highly organized, organs and organ systems that are important in nature, but their combinations, which allow animals to adapt in the ever-changing world around them. For example, warm-bloodedness is achieved due to thermoregulation provided by the coat. Excess heat is excreted together with sweat through the sweat glands of the skin (sweat is similar in composition to urine, but less concentrated).

The class Mammals is divided into two subclasses: first beasts and animals, In a subclass FIRST BEASTS taxonomists distinguish 3-4 extinct orders and 1 order of Monotremes, which includes 4 living species - 3 species of echidna (live in Australia and New Guinea) and 1 species - platypus living in Australia and Tasmania. The subclass of the Primordial Beasts, or cloacals, includes the most primitive of mammals. They lay eggs and incubate them like a platypus, or carry them in a brood pouch (a skin pouch on their belly) like a echidna. There are no nipples in the cloacae, and the ducts of the mammary glands open directly on the skin. The body temperature is lower than that of other mammals, and is approximately 32 degrees. Even outwardly, the first animals differ from other mammals, for example, the muzzle of the echidna is elongated, pointed and has a beak dressed with a horn cover; and in the platypus, the muzzle ends in a wide beak, also covered with a horny sheath with numerous horny plates on the inner surface.

In the second subclass - BEASTS includes 18 modern orders (and about 12-14 orders, whose representatives have now become extinct). In the subclass Animals, all mammals are further divided into lower beasts and higher animals. The lower animals include 1 squad - marsupials, to the highest - all the rest. The order Marsupials includes about 250 species of animals, various in size: from 4 cm (marsupial mouse) to 1.6 m (large gray kangaroo), but identical in ability to give birth to underdeveloped embryos, and then carry them in a bag. On the inside of the bag there are nipples, into which the ducts of the mammary glands open. A born cub (weighing only a few grams) rolls along the path licked by the mother on the stomach into a bag, where it sticks to the nipple and grows for 2-6 months. Among the representatives of the order are the following animals: opossums, marsupial mice, marsupial wolves, marsupial anteaters, marsupial moles, marsupial badgers (bandicoots), couscous, marsupial bears (koala), wombats, kangaroos (51 species).

The higher animals, or placentals, unite 17 orders of Beasts, whose cubs are more or less developed at birth and can suck milk themselves: Insectivores(370 species of plantigrade animals with spines or soft coat - hedgehogs, moles, shrews); detachment bats(850 species of mammals adapted to flight with a skin flying membrane: fruit bats, the bats, lancetons, bag-wings, vampires, horseshoe bats, common bats, bulldogs); detachment Lagomorphs(60 species of animals with double incisors in the upper jaw: pikas, hares); detachment rodents(about 2000 species of predominantly small herbivorous animals with a pair of powerful, constantly growing upper and lower incisors: beavers, marmots, squirrels, muskrats, chinchillas, mice, voles, lemmings, dormice, ground squirrels, hamsters, jerboas, chipmunks, rats, porcupines, marine pigs, nutria); detachment cetaceans(80 species of animals that have adapted to life in the water, with a torpedo-shaped body shape and forelimbs that have changed into flippers: baleen whales (feed on plankton, straining it through a whalebone, - bowhead whale, blue whale, gray and humpback whales) and toothed whales ( dolphins, sperm whales, beaked, bottlenose, etc.)); detachment Predatory(240 species of mostly carnivorous animals with well-developed fangs: wolves, foxes, arctic foxes, raccoons, bears, sable, martens, sea otters, ermines, otters, weasels, ferrets, dew-catfish, skunks, tigers, leopards, lynxes, lions, cheetahs, hyenas, mongooses); detachment pinnipeds(30 species of animals that spend most of their lives in the water and come ashore to rest, give birth to cubs and during molting; have a coat and a thick layer of subcutaneous fat: seals, fur seals, seals, walruses); detachment proboscis(represented only by elephants - animals that have a strongly elongated muscular nose, fused with the upper lip - a trunk); detachment Odd-toed ungulates(16 species of animals in which the third finger is most developed, the rest of the fingers are reduced and everything is covered with a horny hoof: rhinos, zebras, donkeys, horses, kulans); detachment artiodactyls(170 species of animals with four-fingered limbs, overgrown third and fourth fingers, covered with hooves: non-ruminant - pigs, hippos, wild boars; ruminants - deer, roe deer, elk, giraffes, antelopes, saigas, goats, rams, buffaloes, bison, bison, gazelles; callosities - camels); detachment Primates(190 species of plantigrade animals with five-fingered limbs, the first finger is opposed to the rest. They are distinguished by their large brain size and complex behavior: lower primates (semi-monkeys) - tupai, lorises, lemurs; higher primates (monkeys) - capuchins, marmosets, monkeys, gorillas, chimpanzees, orangutans, people (1 subspecies - Homo sapiens)).

Mammals have conquered all faunal areas of the earth, they have mastered different habitats: terrestrial, water and air. Some feel great living in a soil environment. Along with birds, insects and flowering plants, mammals dominate biogeocenoses throughout the Cenozoic. It is impossible to overestimate the importance of mammals both for natural ecosystems and for human economic use. In addition to game animals, people use 15 types of domesticated animals (cows, goats, horses, pigs, rabbits, etc.). Another 20 species of animals are at different stages of domestication (first of all, fur-bearing animals - mink, sable). In the process of selection, more than 200 breeds of dogs alone have been bred. The mass of animals is used as laboratory (mice). Unfortunately, among mammals there are agricultural pests and carriers (voles, ground squirrels, mice) of pathogens of dangerous diseases (plague, tularemia, relapsing fever, hemorrhagic fever). Under the direct and indirect influence of man, the fauna of mammals is depleted. In order to stop this process and preserve the biodiversity of mammals available today, reserves and reserves, national parks and reserves are being created, where the number of declining and endangered species is maintained. Seven species of mammals are listed in the Red Book of the Middle Urals: muskrat, common hedgehog, European mink and three species of bats: northern leather, pond bat and water bat. Of great importance for the conservation of mammals is the prohibition of hunting rare species, the preservation of their habitats, the breeding of animals in captivity (or in special reserves) with subsequent re-acclimatization in their natural habitats.

HUMAN passed a long way of development not only as a social being, but also as a biological species. Anthropology - a science that studies the physical characteristics of a person and his ancestors; dynamics of their development in time and space. Under anthropogenesis. understand the study of human ancestral forms. Under paleoanthropology - the study of fossil human populations that already belong to the modern species. Ideas about the natural origin of man from ape-like ancestors as a result of evolution existed even in ancient times. However, the main role in proving the animal origin of man was played by Charles Darwin's book The Origin of Man and Sexual Selection (1871), which contained facts from various areas of biology, testifying to the development of man from the trunk of ancient monkeys. At the same time, Charles Darwin emphasized that modern great apes cannot be considered as human ancestors - they are our "cousins". Probably the most plausible hypothesis is the origin of man from highly developed apes of the Tertiary period. Anthropological finds have confirmed the essential proximity of man to African great apes (pongid), primarily chimpanzees. The early stages of the evolution of the pongid-hominid trunk are represented by the North African Oligocene Egyptithecus and the Dryopithecus group. It is believed that the separation of the branch that led to man from the common trunk of primate development occurred no earlier than 14-15 and no later than 6 million years ago. So, in zoological terms, modern man belongs to the type of Chordates, the subtype of Vertebrates, the class of Mammals, the subclass of Placentals, the order of Primates, the suborder of Narrow-nosed, the genus Homo, the species Homo sapiens (reasonable man), the subspecies of Homo sapiens sapiens. Modern great apes - chimpanzees, gorillas, orangutans, gibbons - represent forms that have deviated from the line of development common with man. According to the latest data, the finds of the remains of ape-like human ancestors date back to 40 million years (in 1999, a group of French and Russian anthropologists on the territory of the state of Myanmar (Burma) in South Asia found the lower jaw of a primate, which differs in a number of features from the bones of monkeys).

The appearance of a reasonable person on Earth was preceded by several types of humanoid creatures - hominoids and primitive people - hominids. The family of hominoids includes two genera: Ramapithecus and Australopithecus. Ramapithecus lived about 14 million years ago in Southeast Africa, Western and South Asia, when savannahs began to appear on the site of tropical forests. It was at this time that the Ramapithecus “came out of the forest” and began to adapt to life in open spaces. The physical restructuring of the body led to the fact that some Ramapithecus, when looking out for prey and enemies in the thick grass of the savannas, rose on their hind legs, acquiring a straightened body position, which turned out to be extremely beneficial for these individuals in the struggle for existence. Today it is widely believed that the Ramapithecus were the branch of development that led to the appearance of great narrow-nosed monkeys - orangutans.

At the basis of the development of the line of primates that led to the emergence of the genus Homo, there were representatives of the genus Australopithecus (perhaps, some of the most advanced Ramapithecus populations laid its foundation). Australopithecus lived on Earth approximately 5-8 million years ago. The body of australopithecines was covered with hair, and there was a lot of ape in their appearance. They had a height of about 150 cm, were able to walk on their hind legs with a straightened body position, and the front paws served as hands. The mass of the brain of Australopithecus was 450-550 g (the mass of the brain of gorillas was 460 g). Australopithecus, living in open spaces, lived in caves for some time. The poorly developed fangs of the latter indicate that the function of defense and attack should have passed to the hands (in a number of caves that are sites of Australopithecus, bones of small monkeys were found with traces of strong splitting blows, apparently inflicted with sticks or stones). Consequently, Australopithecus hunted using primitive tools.

About 3 million years ago, direct ancestors separated from the African hominoid - Australopithecus in East Africa modern man- hominids - species of the genus Homo. The first species was called a skilled man (Homo habilis), because he began to make stone tools (the most ancient of them, found in the Oldowska Gorge by M. Leakey, hewn pebbles about 2.4 million years old). The mass of the creature's brain was 650 g (up to 775 g), which is already noticeably higher than that of Australopithecus. In a skilled man, changes were found in the skeleton of the limbs: the first toe was not laid aside and the terminal phalanges of the fingers were as short and flat as in a modern person. Most likely, the development of fire took place in the same period. The next species was called erect man (Homo erectus). Upright man in the evolution of hominids is represented by a large number of forms, of which the most famous are: Pithecanthropus (Java), Sinanthropus (China), Heidelberg man (Central Europe), Atlanthropus (Algeria), Telanthropus (South Africa), Oldowan Pithecanthropus (Central and Eastern Africa). From a zoological point of view, all forms of an upright man arose due to the fact that, settling, he fell into new conditions of existence, forming groups isolated from each other, in which natural selection was independently carried out.

All these forms, which existed simultaneously or partially, replacing each other, lived from about 3 million to 200 thousand years ago. In anthropology, the forms of an upright person are often combined under the name archanthropes. Archantropes were generally characterized by developed tool activity, they could butcher killed animals after a successful hunt. They also used vegetable raw materials for food: berries, fruits, roots, greens. They led a herd life. They lived in caves. They used fire. Outwardly, they were similar to modern humans, although in such features as a powerfully developed superciliary ridge, the absence of a real chin protrusion, a low and sloping forehead and a flat nose, the archanthropes were still quite different from later forms of man. The average height was about 160 cm. The mass of the brain reached 800-1000 g. The archanthropes crossed the Rubicon (the weight of the brain is considered to be about 750 g, it is at this time that the child masters speech). Therefore, archanthropes could communicate articulately.

After a period of maximum prosperity, i.e., about 400 thousand years ago, all these forms began to disappear rapidly, apparently giving rise to a new group of forms - paleoanthropes, or Neanderthals (Homo sapiens). Neanderthals inhabited the north of the Mediterranean and the entire territory of Asia Minor until Central Asia(Turkmenistan), Central and East Asia up to and including Indonesia. It should be noted that not all scientists consider Neanderthals to be a species of Homo sapiens, which later gave rise to the subspecies Homo sapiens sapiens - some suggest that Neanderthals were just a blind branch of hominids and died out about 25 thousand years ago. The Neanderthals got their name from the place of the first fossil find (in the valley of the Neandertal River, near Düsseldorf). Neanderthals are characterized by: a low sloping forehead, a low occiput, a solid supraorbital ridge, a large face with spaced eyes, a weak development of the chin protrusion, large teeth, a height of about 165 cm, a brain mass of about 1500 g, hands with wide hands, fingers with nails, no well developed coat. Neanderthals lived in groups. They were engaged in hunting and gathering, and the first type of activity was mainly carried out by men, and the second - by women. During this period of evolution, cannibalism was characteristic of man. The tools of labor were more advanced than those of the archanthropes: hand axes, pointed and side-scrapers, axes and chisels. The level of development of Neanderthals represented a heterogeneous group. The older finds of anthropologists are more progressive morphologically than much later forms. Among such more progressive morphological finds are the Cro-Magnons.

Early Neanderthals (Cro-Magnons) were characterized by a smaller brow ridge, thinner jaws, a high forehead, a noticeably developed chin, less powerful physical development, but more developed brain- well-formed anterior frontal lobes. Later Neanderthals lived in herds and survived for a time due to powerful physical development. In associations of early Neanderthals, there were undoubtedly intra-group bonds, a hierarchy of individuals and altruistic behavior. Apparently, it was from them that the subspecies of Homo sapiens sapiens, to which all modern people belong, originated 50-40 thousand years ago.

Today, there are several points of view on the origin of modern man. The concept of broad monocentrism dominates, according to which a modern type of man (neoanthrope) arose somewhere in the Eastern Mediterranean and in Western Asia. It is there that the most complete intermediate forms between the early (Cro-Magnon) and late Neanderthals are found. In those days, these territories were covered with dense forests, in which a huge number of animals lived. Here, apparently, the last step on the way to Homo sapiens was made. About 10 thousand years ago, man completely populated the entire earth, with the exception of Antarctica (which was also covered with ice at that time). In subsequent periods, due to climate change, there was only a redistribution of man as a biological subspecies across the territory of the range.

On the last step evolution, the action of natural selection led to the formation races, which had adaptive significance in certain parts of the geographic environment (all races belong to the same subspecies, although there are some anatomical and morphological differences between them, the genetic basis of the differences is small). At the moment, the following races are distinguished: equatorial (Negro-Australoid), Eurasian (Caucasian), Asian-American (Mongoloid). There is another subdivision - into the Negroid, Australoid, Caucasoid, Mongoloid and American races. Within each race there is a division into subraces, for example, within the Caucasoid race, the Atlanto-Baltic, Central European, Indo-Mediterranean, White Sea-Baltic and Balkan-Caucasian subraces are distinguished. The greatest achievements of the evolution of Homo sapiens were the discoveries that led to the Neolithic revolution - the domestication of animals and the cultivation of plants (30-10 thousand years ago); the development of culture, as well as the scientific and technological revolution, which created the basis for powerful social development.

The transformation of energy in the process of metabolism in the body is carried out in full accordance with the first and second laws of thermodynamics. Nevertheless, a living organism, as an object of thermodynamic research, differs from the systems of chemical thermodynamics. Here are some features:

A living organism is an open system that continuously exchanges matter and energy with the environment.

· The application of the second law of t/d-ki to living systems is unthinkable without taking into account the influence of biological laws. The nature of the change in entropy, which is of decisive importance in non-living systems, in the case of biological systems is only of subordinate importance.

All biochemical processes occurring in the cells of living organisms proceed at a constant temperature, pressure, with slight differences in concentrations, without sudden changes in volume, etc.

The main source of energy of a living organism is the chemical energy contained in food products, part of which is spent on:

Performing work inside the body related to respiration, blood circulation, movement of metabolites, etc.

· Heating of inhaled air, consumed food, water.

Coverage of heat losses in environment with direct radiation and evaporation of moisture from the surface of the body, with inhaled air, with waste products.

Performing external work with all movements and labor activity of a person.

The main components of food are carbohydrates, fats and proteins.

Calorie content, that is, the energy released in the process of dissimilation with the formation of carbon dioxide and water, averages:

Carbohydrates - 17 kJ / g

Fats - 40 kJ / g

Proteins - 17 kJ / g.

During normal labor activity, a person's energy costs are covered by 60% of carbohydrates, 25% of fats, and 15% of proteins. At proper nutrition the daily consumption rate (excluding heavy physical labor) is:

Carbohydrates 400-500 g,

Fat 60-70 g,

Proteins 80-100g.

The scientific basis for these calculations is the first law of thermodynamics. With food, rather complex macromolecular compounds enter the body, which have many chemical bonds and unrealized chemical affinity. Such substances are characterized by low entropy, high Gibbs energy and enthalpy. In the process of assimilation of food from large molecules of carbohydrates, fats, proteins, daughter molecules are formed with a simpler structure and stronger chemical bonds CO 2, H 2 O, NH 3, etc. This process of dissimilation of a substance, in which a larger number of particles is formed from a smaller number of particles , entails an increase in entropy (ΔS > 0). Due to the strengthening of chemical bonds and the realization of chemical affinity, the Gibbs energy of the system decreases. The enthalpy of the system (ΔH<0).

In 1946, the American scientist I. Prigogine proposed one of the main theorems of the thermodynamics of open systems: “In a stationary thermodynamically open system, the rate of energy production, due to the occurrence of irreversible processes in it, takes the minimum positive value for these conditions.

Since entropy is a measure of energy dissipation, Prigogine's theorem leads to an important conclusion. In the stationary state, the dissipation of the Gibbs energy by an open system turns out to be minimal. Thus, a living organism, which is an open stationary system, is placed by nature in favorable conditions in terms of energy supply: maintaining a constant internal environment (homeostasis) requires a minimum consumption of Gibbs energy.

1.1. Life is a macromolecular open system, which is characterized by a hierarchical organization, the ability to self-renewal, metabolism and a finely regulated process.

1.2. properties of living matter.

Living properties:

1. Self-renewal, which is associated with a constant exchange of matter and energy, and which is based on the ability to store and use biological information in the form of unique information molecules: proteins and nucleic acids.

2. Self-reproduction, which ensures continuity between generations of biological systems

3. Self-regulation, which is based on the flow of matter, energy and information

4. Most of the chemical processes in the body are not in a dynamic state.

5. Living organisms are capable of growth

living signs:

1. Exchange of matter and energy

2. Metabolism is a special way of interaction of living organisms with the environment

3. Metabolism requires a constant influx of certain substances and energy from outside and the release of certain dissimilation products into the external environment. The body is an open system

4. Irritability - is the transfer of information from the external environment to the body; based on irritability, self-regulation and homeostasis are carried out

5. Reproduction - reproduction of one's own kind

6. Heredity - the flow of information between generations, resulting in continuity

7. Variability - the emergence of new signs in the process of reproduction; basis of evolution

8. Ontogenesis - individual development, implementation of an individual program

9. Phylogeny - historical development, evolutionary development is carried out as a result of hereditary variability, natural selection and the struggle for existence

10. Organisms are included in the process of evolution

4. Chemical composition of living organisms

The basis of living things is made up of two classes of chemical compounds - proteins and nucleic acids. Moreover, in living organisms, unlike inanimate matter, these compounds are characterized by the so-called chiral purity. In particular, proteins are built only on the basis of levorotatory (polarizing light to the left) amino acids, while nucleic acids are composed exclusively of dextrorotatory sugars. This chiral purity developed at the very initial stages of the evolution of living matter. It is believed that the minimum time of the global transition from complete chaos to chiral purity is from 1 to 10 million years. Consequently, in this sense, the origin of life could have occurred on Earth relatively instantaneously over a period of time 5,000 times less than the estimated age of the planet.

Proteins are primarily responsible for the metabolism and energy metabolism in a living system, i.e. for all the reactions of synthesis and decay that take place in any organism from birth to death. Nucleic acids provide the ability of living systems to reproduce themselves. They are the basis of the matrix, the amazing "invention" of nature. The matrix represents a kind of blueprint, i.e., a complete set of information on the basis of which species-specific protein molecules are synthesized.

In addition to proteins and nucleic acids, living organisms contain lipids (fats), carbohydrates, and very often ascorbic acid.

Many chemical elements present in the environment have been found in living systems, but only about 20 of them are necessary for life. These elements are called biogenic. On average, about 70% of the mass of organisms is oxygen, 18% - carbon, 10% - hydrogen (substances-organogens). Next come nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, sodium, chlorine, and iron. These so-called universal biogenic elements, present in the cells of all organisms, are often called macronutrients.

Some elements are found in organisms in extremely low concentrations (not higher than a thousandth of a percent), but they are also necessary for normal life. These are biogenic trace elements. Their functions and roles are very diverse. Many trace elements are part of a number of enzymes, vitamins, respiratory pigments, some affect growth, development rate, reproduction, etc.

The presence in the cells of a number of elements depends not only on the characteristics of the organism, but also on the composition of the environment, food, environmental conditions, in particular, on the solubility and concentration of salts in the soil solution. A sharp deficiency or excess of biogenic elements leads to abnormal development of the organism or even to its death. Additives of biogenic elements to the soil to create their optimal concentrations are widely used in agriculture.

Mineral elements, also called bioelements, play an important role in the human body: they are a building material (calcium, phosphorus, iron); regulate many biochemical processes during metabolism (potassium, sodium, iodine, chlorine, copper, manganese, selenium and others); take part in the process of blood coagulation (calcium); maintain the body's water balance (sodium, potassium); affect the preservation of acid-base balance; are part of enzymes (enzymes). Bioelements are divided into two groups: Macronutrients present in large quantities in food (up to several percent of dry weight) and necessary for the body in specific weight quantities for its proper functioning. Trace elements required by the body in trace amounts (of the order of 10-2 to 10-11% of the body's live weight). They are very important for metabolic processes and the production of hormones and enzymes.

(additionally more material) All living organisms selectively relate to the environment. The composition of the chemical elements of living systems differ from the chemical elements of the earth's crust. In the earth's crust O, Si, Al, Na, Fe, K, in living organisms H, O, C, N. All other elements less than 1%. In any living organism, you can find all the elements of the environment, however, in different quantities. However, this does not mean that they are necessary. 20 chemical elements are needed - those without which a living system cannot do. Depending on the environment and metabolism, the set of these substances is different. Some chemical elements are part of all living organisms (universal chemical elements) H, C, N, O. Na, Mg, P, S, Ca, K, Cl, Fe, Cu, Mn, Zn, B, V, Si, co, Mo. Silicon is part of mucopolysaccharides of connective tissue.

The composition of living organisms includes 4 elements that are surprisingly suitable for performing the functions of a living thing: O, C, H, N. They share the common property that they readily form covalent bonds through electron pairing. C atoms have the property that they can combine into long chains and rings, with which other chemical elements can bind. There are a lot of C connections. Silicon is closest to carbon, but C forms CO2, which is widespread in nature and available to everyone, and silicon oxide is an element of sand (insoluble).

Macromolecules - nucleic acids, proteins, polypeptides, lipids, polysaccharides - polymers formed by monomers connected by covalent bonds. Any living organism is 90% composed of 6 chemical elements - C, O, H, P, N, S - bioelements(biogenic elements).

Cell

All living organisms use common materials for life. About 120 are used (20 amino acids, 5 nitrogenous bases, 4 classes of lipids, small molecules - simple acids, water, phosphates - 70). These are products of chemical evolution (organic compounds of living systems and components of inanimate matter).

Hierarchy of cellular organization - see the lecture (+ textbook page 27)

Modern science divides all nature into living and non-living. At first glance, this division may seem simple, but sometimes it is quite difficult to decide whether a certain one is really alive or not. Everyone knows that the main properties, signs of living things are growth and reproduction. Most scientists use seven life processes or signs of living organisms that distinguish them from inanimate nature.

What is characteristic of all living beings

All living beings:

• They are made up of cells.
• They have different levels of cellular organization. Tissue is a group of cells that perform a common function. An organ is a group of tissues that perform a common function. An organ system is a group of organs that perform a common function. An organism is any living being in a complex.
• They use the energy of the Earth and the Sun, which they need for life and growth.
• React to the environment. Behavior is a complex set of reactions.
• Grow. Cell division is the orderly formation of new cells that grow to a certain size and then divide.
• They breed. Reproduction is not essential for the survival of individual organisms, but it is essential for the survival of the entire species. All living things reproduce in one of the following ways: asexual (production of offspring without the use of gametes), sexual (production of offspring by combining sex cells).
• Adapt and adapt to environmental conditions.

The main features of living organisms

• Motion. All living things can move and change their position. This is more obvious in animals, which can walk and run, and less so in plants, parts of which can move to follow the movement of the sun. Sometimes the movement can be so slow that it is very difficult to see it.

• Respiration is a chemical reaction that takes place inside the cell. This is the process of releasing energy from food substances in all living cells.
• Sensitivity - the ability to detect changes in the environment. All living beings are capable of responding to stimuli such as light, temperature, water, gravity, and so on.

• Growth. All living beings grow. The constant increase in the number of cells and body size is called growth.
• Reproduction - the ability to reproduce and transmit genetic information to their offspring.

• Excretion - getting rid of waste and toxins. As a result of many chemical reactions occurring in cells, it is necessary to get rid of metabolic products that can poison the cells.
• Nutrition - the intake and use of nutrients (proteins, carbohydrates and fats) necessary for growth, tissue repair and energy. This happens differently for different types of living beings.

All living things are made up of cells

What are the main features The first thing that makes living organisms unique is that they are all made up of cells, which are considered the building blocks of life. Cells are amazing, despite their small size, they can work together to form large body structures such as tissues and organs. Cells are also specialized - for example, liver cells are located in the organ of the same name, and brain cells function only in the head.

Some organisms are made up of just one cell, such as many bacteria, while others are made up of trillions of cells, such as humans. are very complex creatures with incredible cellular organization. This organization begins with DNA and extends throughout the body.

reproduction

The main signs of a living thing (biology describes this even in a school course) also include such a thing as reproduction. How do all living organisms get to Earth? They do not appear out of thin air, but through reproduction. There are two main ways to produce offspring. The first is the well-known sexual reproduction. This is when organisms produce offspring by combining their gametes. Humans and many animals fall into this category.

Another type of reproduction is asexual: organisms produce offspring without a gamete. Unlike sexual reproduction, where offspring have a different genetic makeup than either parent, asexual reproduction produces offspring that are genetically identical to their parent.

Growth and development

The main features of the living also imply growth and development. When offspring are born, they don't stay that way forever. The man himself is a great example. In the process of growth, people change, and the more time passes, the more these differences are noticeable. If we compare an adult and a baby, which he once came into this world, then the differences are simply colossal. Organisms grow and develop throughout life, but these two terms (growth and development) do not mean the same thing.

Growth is when the size changes, from small to large. For example, with age, all organs of a living organism grow: fingers, eyes, heart, and so on. Development implies the possibility of change or transformation. This process begins even before birth, when the first cell appears.

Energy

Growth, development, cellular processes and even reproduction can only occur if living organisms receive and can use energy, which is also included in the main features of a living being. All life energies ultimately come from the sun, and this force gives energy to everything on Earth. Many living organisms, such as plants and some algae, use the sun to produce their own food.

The process of converting sunlight into chemical energy is called photosynthesis, and the organisms that can produce it are called autotrophs. However, many organisms cannot make their own food and therefore must feed on other living organisms for energy and nutrients. Organisms that feed on other organisms are called heterotrophs.

Responsiveness

Listing the main features of wildlife, it is important to note the fact that all living organisms have the ability to respond in a certain way to various environmental stimuli. This means that any changes in the environment trigger certain reactions in the body. For example, a Venus flytrap will close its bloodthirsty petals pretty quickly if an unsuspecting fly lands there. If possible, the turtle will come out to bask in the sun rather than stay in the shade. When a person hears a rumbling in his stomach, he will go to the refrigerator to make a sandwich, and so on.

Stimuli can be external (outside the human body) or internal (inside the body), and they help living organisms maintain balance. They are represented as various sense organs in the body, such as: sight, taste, smell and touch. The rate of response may vary depending on the organism.

homeostasis

The main features of living organisms include regulation which is called homeostasis. For example, temperature regulation is very important for all living beings, because body temperature affects such an important process as metabolism. When the body becomes too cold, these processes slow down and the body may die. The opposite happens if the body overheats, the processes are accelerated, and all this leads to the same disastrous consequences.

What do living beings have in common? They must have all the basic features of a living organism. For example, a cloud can grow in size and move from one place to another, but it is not a living organism because it does not have all of the above characteristics.