Basic terms in biology for passing the OGE. Assignments: biological terms and concepts

Biological terms of cytology

Homeostasis(homo - identical, stasis - state) - maintaining the constancy of the internal environment of a living system. One of the properties of all living things.

Phagocytosis(phago - devour, cytos - cell) - large solid particles. Many protozoans feed by phagocytosis. With the help of phagocytosis, immune cells destroy foreign microorganisms.

Pinocytosis(pino - drink, cytos - cell) - liquids (together with dissolved substances).

Prokaryotes, or prenuclear (pro - do, karyo - nucleus) - the most primitive structure. Prokaryotic cells do not have formalized, no, genetic information is represented by one circular (sometimes linear) chromosome. Prokaryotes lack membrane organelles, with the exception of photosynthetic organelles in cyanobacteria. Prokaryotic organisms include Bacteria and Archaea.

Eukaryotes, or nuclear (eu - good, karyo - nucleus) - and multicellular organisms that have a formed nucleus. They have a more complex organization compared to prokaryotes.

Karyoplasm(karyo - nucleus, plasma - contents) - the liquid contents of the cell.

Cytoplasm(cytos - cell, plasma - contents) - internal environment of the cell. Consists of hyaloplasm (liquid part) and organoids.

Organoid, or organelle(organ - instrument, oid - similar) - a permanent structural formation of a cell that performs certain functions.

In prophase 1 of meiosis, each of the already twisted bichromatid chromosomes closely approaches its homologous one. This is called conjugation (well, confused with conjugation of ciliates).

A pair of homologous chromosomes that come together is called bivalent.

The chromatid then crosses over with a homologous (non-sister) chromatid on the neighboring chromosome (with which the bivalent is formed).

The place where chromatids intersect is called chiasmata. Chiasmus was discovered in 1909 by the Belgian scientist Frans Alphonse Janssens.

And then a piece of the chromatid breaks off at the site of the chiasm and jumps to another (homologous, i.e., non-sister) chromatid.

Gene recombination has occurred. Result: some genes migrated from one homologous chromosome to another.

Before crossing over, one homologous chromosome possessed genes from the maternal organism, and the second from the paternal one. And then both homologous chromosomes possess the genes of both the maternal and paternal organism.

The meaning of crossing over is this: as a result of this process, new combinations of genes are formed, therefore, there is more heritable variability, and therefore there is a greater likelihood of the emergence of new traits that may be useful.

Mitosis– indirect division of a eukaryotic cell.

The main type of cell division in eukaryotes. During mitosis, there is a uniform, equal distribution of genetic information.

Mitosis occurs in 4 phases (prophase, metaphase, anaphase, telophase). Two identical cells are formed.

The term was coined by Walter Fleming.

Amitosis– direct, “incorrect” cell division. Robert Remak was the first to describe amitosis. Chromosomes do not spiral, DNA replication does not occur, spindle threads do not form, and the nuclear membrane does not disintegrate. The nucleus is constricted, with the formation of two defective nuclei, with, as a rule, unevenly distributed hereditary information. Sometimes even the cell does not divide, but simply forms a binuclear cell. After amitosis, the cell loses the ability to undergo mitosis. This term was coined by Walter Fleming.

• ectoderm (outer layer),
• endoderm (inner layer) and
• mesoderm (middle layer).

Common amoeba –

protozoan of the Sarcomastigophora type (Sarcoflagellates), class Rhizomes, order Amoeba.

The body does not have a permanent shape. They move with the help of pseudopods - pseudopodia.

They feed by phagocytosis.

Ciliate slipper- heterotrophic protozoan.

Type of ciliates. The organelles of movement are cilia. Food enters the cell through a special organoid - the cellular mouth opening.

There are two nuclei in a cell: large (macronucleus) and small (micronucleus).

Yeast- unicellular fungi. Used in cooking and alcohol production

Formed on wet soil or food. It looks like a fluffy white coating, which then turns black from the spores formed. Used to obtain fermentation products.

Consists of processes:

• synthesis (synonyms - anabolism, assimilation), comes with energy absorption.
• decay (synonyms - catabolism, dissimilation) —

Catabolism and dissimilation are reactions of breakdown and oxidation of complex organic substances with the release of energy in the form of heat and ATP.

Three stages:

1. preparatory - the breakdown of the polymer components of food into monomers (in higher organisms occurs in the digestive tract, in protozoa - in lysosomes);
2. oxygen-free (a name = "Glikoliz">glycolysis, anaerobic respiration, fermentation); goes in the cytoplasm of the cell:
   glucose → pyruvic acid (PVA) + 2ATP
3. oxygen breakdown (aerobic) - occurs on the cristae of mitochondria):
   PVC → CO2 + H2O + 36ATP

ATP— Adenosine triphosphoric acid (adenosine triphosphoric acid is a universal biological energy accumulator. It consists of the nitrogenous base adenine, a five-atomic sugar - ribose and three phosphoric acid residues.

– the process of synthesis of glucose and other organic substances from carbon dioxide and water using the energy of sunlight.

Characteristic of plants and some autotrophic protozoa.

6CO 2 + 6H 2 O -> C 6 H 12 O 6 + 6O 2

Consists of two successive phases:

• light (in the thylakoids of the chloroplast grana) and
• dark (in the stroma of the chloroplast).

Chemosynthesis– one of the methods of autotrophic nutrition.

In chemosynthesis, the energy for the formation of complex molecules is obtained from chemical reactions of oxidation of inorganics. This method is typical for prokaryotes.

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Division of the nervous system that innervates internal organs. The autonomic nervous system consists of sympathetic and parasympathetic parts.

Adrenaline is a hormone of the adrenal medulla, the secretion of which increases in stressful situations.

An axon is a process of a neuron through which excitation is transmitted to other neurons or to the working organ.

The alveolus is a bubble-like formation in the lungs, entwined with blood capillaries.

Analyzers are complex systems of sensitive nervous formations that perceive information from the environment and analyze it (visual, auditory, gustatory, etc.). Each analyzer consists of three sections: peripheral (receptors), conductor (nerve) and central (corresponding area of ​​the cerebral cortex). Currently, along with the term analyzer, the concept of “sensory system” is used.

Androgens are male sex hormones produced mainly by the testes, as well as the adrenal cortex and ovaries.

Antigens are substances that are perceived by the body as foreign and cause a specific immune response.

Antibodies are proteins in human blood plasma that have the ability to bind antigens. By interacting with microorganisms, antibodies prevent their reproduction and/or neutralize the toxic substances they release.

Aorta is the main artery of the circulatory system; supplies blood to all tissues and organs of the body.

Arteries are blood vessels that carry oxygenated blood from the heart to the organs and tissues of the body.

The eardrum is a thin membrane that separates the external auditory canal from the tympanic cavity in the human ear.

Unconditioned reflexes are relatively constant, innate reactions of the body to influences from the external world, carried out with the help of the nervous system. For example, blinking, sucking, sneezing in newborns.

Pregnancy is a physiological process in a woman’s body during which a fetus develops from a fertilized egg. Lasts on average 280 days. It ends with childbirth - the birth of a child.

Myopia is a lack of vision in which close objects are clearly visible and distant objects are poorly visible.

The vagus nerve is a large parasympathetic nerve that slows the rhythm and force of heart contractions.

Bronchi are air passages connecting the trachea and lungs.

Veins are blood vessels that carry blood from organs and tissues to the heart.

Vitamins are low molecular weight organic compounds that have high biological activity and are involved in metabolism. A person should receive vitamins from food. With their deficiency, vitamin deficiencies develop - diseases associated with metabolic disorders. There are water-soluble (C, B1, B6, etc.) and fat-soluble (A, E, D, etc.) vitamins.

Taste analyzer - perceives and analyzes soluble chemical irritants acting on the organ of taste (tongue).

The inner ear is a system of communicating, fluid-filled canals and cavities in the cartilaginous or bony labyrinth of vertebrates and humans. The inner ear contains the perceptive parts of the organs of hearing and balance - the cochlea and the vestibular apparatus.

Excitability is the ability of organs and tissues to respond to stimuli with a specific reaction - excitation, in which a living system moves from a state of rest to activity.

Villi are microscopic outgrowths of the intestinal mucosa that increase the absorption surface many times over.

Inflammation is a complex adaptive vascular-tissue reaction of the body to the effects of various pathogenic agents: physical, chemical, biological.

Absorption is a set of processes that ensure the transfer of substances from the digestive tract to the internal environment of the body (blood and lymph).

Excretion (excretion) - removal from the body into the environment of the final metabolic products - water, salts, etc.

Higher nervous activity is the activity of the higher parts of the central nervous system, ensuring the most perfect adaptation of a person to the environment. The basis of higher nervous activity is conditioned reflexes. The doctrine of higher nervous activity was created by I. P. Pavlov.

Gamete is a sex cell.

A ganglion is a nerve ganglion located outside the central nervous system. Formed by a cluster of neuron cell bodies.

Hemoglobin is the red respiratory pigment of human blood. A protein that contains iron (II). Found in red blood cells. Transports oxygen from the respiratory organs to the tissues and carbon dioxide from the tissues to the respiratory organs. Co-

The amount of hemoglobin in human blood is 130-160 g/l, slightly less in women than in men.

Hygiene is a field of medicine that studies the influence of living and working conditions on human health. Develops measures to prevent diseases, ensure optimal living conditions, preserve health and prolong life.

The hypothalamus is a section of the diencephalon in which the centers of the autonomic nervous system are located. Closely related to the pituitary gland. The hypothalamus regulates metabolism, the activity of the cardiovascular, digestive, excretory systems and endocrine glands, the mechanisms of sleep, wakefulness, and emotions. Connects the nervous and endocrine systems.

The pituitary gland is an endocrine gland that produces hormones that affect the growth and development of the body, as well as metabolic processes. The pituitary gland regulates the activity of other endocrine glands. Lesions of the pituitary gland lead to various diseases - dwarfism, gigantism, etc.

Glycogen is a polysaccharide formed by glucose molecules. It is synthesized and deposited in the cytoplasm of liver and muscle cells. Glycogen is sometimes called animal starch because it serves as a storage nutrient.

The pharynx is a section of the digestive canal that connects the oral cavity with the esophagus, and the nasal cavity with the larynx.

Homeostasis is the relative dynamic constancy of the composition and properties of the internal environment of the body, as well as the mechanisms that ensure this stability.

The brain is a part of the central nervous system located in the cranial cavity. Includes 5 sections: medulla oblongata, posterior (pons and cerebellum), middle, intermediate (thalamus and hypothalamus) and telencephalon (cerebral hemispheres and corpus callosum).

Gonads are sex glands in humans and animals.

Hormones are biologically active substances produced in the body by special cells or organs (endocrine glands) and released into the blood. Hormones have a targeted effect on the activity of other organs and tissues. With their help, the humoral regulation of body functions is carried out.

The larynx is the initial section of the airways, protects them from food.

The rib cage is a collection of thoracic vertebrae, ribs and sternum, forming a strong support for the shoulder girdle. The space inside the chest (thoracic cavity) is separated from the abdominal cavity by the diaphragm. Inside the chest cavity are the lungs and heart.

Humoral regulation is the coordination of vital processes in the body, carried out through liquid media (blood, lymph, tissue fluid) with the help of hormones and various metabolic products.

Farsightedness is a lack of vision that makes it difficult to see clearly at close range. Depends on the weak refractive power of the cornea and lens or the anteroposterior axis of the eye being too short.

Dendrites are branching processes of neurons that conduct nerve impulses to the body of the nerve cell.

The dermis is the connective tissue part of the skin of vertebrates and humans, located under the outer layer - the epidermis.

The diaphragm is a muscular partition that completely separates the thoracic cavity from the abdominal cavity.

Dominant is a strong, persistent focus of excitation that arises in the central nervous system. The dominant focus has an inhibitory effect on the activity of other nerve centers.

Respiration is a set of processes that ensure the entry of oxygen into the body, its use for the oxidation of organic substances with the release of energy and the release of carbon dioxide into the environment.

The respiratory center is a collection of neurons of the medulla oblongata and other parts of the brain that ensure the rhythmic activity of the respiratory muscles.

Glands are organs that secrete special substances (secrets) that participate in metabolism. There are glands of external, internal and mixed secretion.

Exocrine glands - usually have excretory ducts and secrete secretions onto the surface of the body (sweat, sebaceous) or into the cavities of internal organs (salivary, intestinal, etc.).

Endocrine glands - do not have excretory ducts and secrete the substances they produce into the blood or lymph (pituitary gland, pineal gland, thymus, thyroid and parathyroid glands, etc.).

Glands of mixed secretion - have intra- and exocrine secretion (pancreas and reproductive glands - ovaries and testes).

The macula is an area on the retina located along the optical axis of the eye, where the largest number of cones are concentrated.

Gastric juice is a colorless liquid that contains digestive enzymes, mucus and a solution of hydrochloric acid.

Bile is a secretion produced by liver cells. Contains water, bile salts, pigments, cholesterol. Bile promotes emulsification and

absorption of fats, increased contractions of intestinal muscles, activates pancreatic juice enzymes.

Vital capacity is the sum of tidal volume, expiratory reserve volume and inspiratory reserve volume. Measured by a spirometer.

A zygote is a fertilized egg. The initial stage of embryo development.

The visual analyzer is a set of visual receptors, the optic nerve and parts of the brain that perceive and analyze visual stimuli.

Immunity is the body’s ability to resist the action of damaging agents, maintaining its integrity and biological individuality. Protective reaction of the body.

The immune system is a group of organs (red bone marrow, thymus, spleen, lymph nodes, etc.) involved in the formation of immune cells.

Infectious diseases are diseases caused by pathogenic microorganisms.

Artificial respiration is a treatment technique used to stop natural breathing. The person providing assistance actively blows (exhales) his air into the victim’s lungs. In the absence of heartbeats, it is combined with indirect cardiac massage.

Capillaries are the smallest blood vessels through the walls of which the exchange of substances and gases takes place between the blood and body tissues.

Caries is the gradual destruction of tooth tissue. One of the most common human diseases, manifested in the formation of defects in enamel and dentin.

Valves are folds that separate the parts of the heart and prevent the reverse flow of blood (in humans - tricuspid, bicuspid, or mitral, two semilunar).

Cones are light-sensitive flask-shaped cells (photoreceptors) located in the retina of the human eye. Provides color vision.

The cerebral cortex is a layer of gray matter covering the cerebral hemispheres. The highest department of the central nervous system, regulating and coordinating all the vital functions of the body during its interaction with the environment.

The organ of Corti is the receptor part of the auditory analyzer, located in the inner ear and represented by hair cells in which nerve impulses arise.

Blood is a tissue of the internal environment, the intercellular substance of which is represented by liquid (plasma). In addition to plasma, the composition of blood includes formed elements - erythrocytes, leukocytes, platelets.

Blood pressure is the pressure of blood on the walls of the blood vessels and chambers of the heart, resulting from its contractions and vascular resistance. The pressure at the moment of ventricular contraction is systolic, and during diastole it is diastolic.

Blood circulation is the movement of blood through the system of blood vessels (large and small circles of blood circulation), caused mainly by contractions of the heart.

Leukocytes are human white blood cells. They play an important role in protecting the body from infections - they produce antibodies and absorb bacteria.

Lymph is a fluid circulating through the vessels and nodes of the lymphatic system. Contains a small amount of proteins and lymphocytes. Performs a protective function and also ensures metabolism between body tissues and blood.

The lymphatic system is a collection of lymphatic vessels and nodes through which lymph moves.

Lymphocytes are one of the forms of non-granular leukocytes. Participate in the development and maintenance of immunity.

A mediator is a chemical substance whose molecules are capable of reacting with specific receptors on the plasma membrane of a cell. In this case, its permeability for certain ions changes and an active electrical signal appears. Mediators are involved in the transmission of excitation from one cell to another. The role of mediators is carried out by adrenaline, acetylcholine, norepinephrine, etc.

NREM sleep is a phase of sleep characterized by a decrease in all functions of the human body and the absence of dreams.

Tonsils are collections of lymphoid tissue around the pharynx that play a protective role.

Myocardium is the muscular layer of the heart.

Myofibrils are contractile fibers consisting of protein filaments.

The cerebellum is part of the human hindbrain. Plays a leading role in maintaining body balance and coordination of movements.

The mammary glands are paired human skin glands. Develops in women around puberty. After birth, milk begins to be produced.

Urine is a product of animal and human excretion produced by the kidneys. Consists of water (96%) and the salts it contains, as well as the final

protein metabolic products (urea, uric acid, etc.). In the process of urine formation, primary urine is produced first, and then final urine.

The adrenal glands are paired endocrine glands. The adrenal cortex secretes corticosteroids, as well as partially male and female sex hormones; medulla - adrenaline and norepinephrine. They play an important role in the regulation of metabolism and in the body’s adaptation to unfavorable conditions.

The outer ear is the outer section of the auditory analyzer.

Neuron is a nerve cell, the main structural and functional unit of the nervous system. There are sensory, intercalary and motor neurons. They consist of a body and processes - dendrites and axons, which are involved in the transmission of excitation.

Neurohumoral regulation is the joint regulation of body functions by nervous and humoral mechanisms.

Nervous regulation is the coordinating influence of the nervous system on cells, tissues and organs, bringing their activity into line with the needs of the body.

Nerve fibers are processes of nerve cells that conduct nerve impulses.

Nerves are bundles of nerve fibers covered with a common sheath.

Nephron is the structural and functional unit of the kidneys. It looks like a cup-shaped capsule with a tubule extending from it.

Metabolism is a set of chemical transformations of substances, including the processes of their entry into the body, changes, accumulation and removal of metabolic products. Metabolism is carried out with the participation of enzymes and includes reactions of synthesis and breakdown.

Olfactory sensory system - perceives and analyzes chemical stimuli. It is represented by the epithelium of the nasal cavity, the olfactory nerve and the olfactory centers of the cerebral cortex.

Fertilization is the process of fusion of female and male reproductive cells. As a result of fertilization, a zygote is formed.

Posture is the body position that is familiar to every person when walking, standing and sitting.

Touch - provides the ability to perceive and distinguish the shape, size and nature of the surface of an object.

Rods are light-sensitive cells (photoreceptors) in the retina. Provide twilight vision. Unlike cones, they are more sensitive, but do not perceive colors.

The parasympathetic nervous system is a division of the autonomic nervous system, the centers of which are located in the spinal cord, medulla oblongata and midbrain. Together with the sympathetic nervous system, it participates in the regulation of the activity of all internal organs and glands.

The forebrain is the anterior part of the vertebrate brain, divided into the telencephalon (cerebral hemispheres) and the diencephalon.

The pericardium is the pericardial sac, a connective tissue sac surrounding the heart.

The liver is a digestive gland. In addition to the synthesis of bile, it participates in the metabolism of proteins, etc. Performs a barrier function.

Nutrition is the entry into the human body and its absorption of substances necessary to replenish energy costs, build and renew tissues. Through nutrition, as an integral part of metabolism, the body communicates with the external environment. Insufficient and excess nutrition leads to metabolic disorders (dystrophy, obesity).

Plasma is the liquid part of blood and lymph.

The placenta, the child's place, is the organ that connects the fetus with the mother's body. Oxygen and nutrients are supplied from the mother through the placenta, and metabolic products are removed from the fetus's body. It also performs hormonal and protective functions.

A fetus is a human embryo during the period of intrauterine development after the formation of the main organs and systems (from the 9th week of pregnancy until birth).

Flat feet - flattening of the arch of the foot, causing pain.

The pancreas is a mixed secretion gland. Its exocrine function is to produce enzymes involved in digestion, and its intrasecretory function is to release hormones (insulin, glucagon) that regulate carbohydrate metabolism.

Subcutaneous fat is a type of connective tissue. Serves as an energy depot for the body.

Sweat glands are external secretion glands involved in the secretion of metabolic products and thermoregulation. Located in the skin.

The kidney is an excretory organ. Nitrogen-containing metabolic products are excreted through the kidneys in urine.

Conductivity is the ability of nerve and muscle cells not only to produce, but also to conduct an electrical impulse.

The medulla oblongata is a section of the brain stem located between the pons and the spinal cord. The medulla oblongata contains the centers of breathing, blood circulation, sneezing, coughing, swallowing, etc.

The diencephalon is a part of the brain stem that includes several areas (including the hypothalamus). The diencephalon contains the highest centers of the autonomic nervous system.

Pulse is a periodic oscillation of the walls of the arteries that occurs synchronously with the contractions of the heart.

The iris (iris) is the thin, movable diaphragm of the eye with a pupillary opening in the center. Contains pigment cells that determine eye color.

Irritability is the ability of cells, tissues or the whole organism to respond to changes in the external or internal environment.

Rational nutrition is a nutrition system that maximally satisfies the current energy and plastic needs of the body.

Rh factor is a protein (antigen) found in human blood. About 85% of the world's population have the Rh factor (Rh+), the rest do not have it (Rh-). The presence or absence of the Rh factor is taken into account during blood transfusion.

Reflex is the body’s response to changes in external or internal environmental conditions, carried out with the participation of the nervous system. There are unconditioned and conditioned reflexes.

A reflex arc is a set of nerve formations involved in a reflex. Includes receptors, sensory fibers, nerve center, motor fibers, executive organ (muscle, gland, etc.).

A receptor is a formation that perceives irritation. Receptors can be the endings of nerve fibers or specialized cells (for example, rods and cones in the retina). Receptors convert the energy of the stimulus acting on them into nerve impulses.

The cornea is the anterior transparent part of the sclera that transmits light rays.

Childbirth is a complex physiological act of expulsion of the fetus and placenta (placenta, membranes and umbilical cord) from the uterine cavity.

Sebaceous glands are glands located in the skin that secrete a secretion that gives the skin and hair water-repellent properties and elasticity.

Self-regulation is the ability of a biological system to independently maintain various physiological indicators (blood pressure, body temperature, blood sugar, etc.) at a relatively constant level.

Blood coagulation is a protective reaction of the body, expressed in stopping bleeding (formation of a clot) when a vessel is damaged.

Secretion is the process of formation and release of special substances - secretions - from gland cells.

The spleen is an unpaired organ of vertebrates and humans, located in the abdominal cavity. Participates in hematopoiesis, metabolism, performs immunobiological and protective functions.

Testes (testes) are male reproductive glands in which sperm are produced.

The cardiac cycle is a period that includes one contraction and one relaxation of the heart.

The heart is the main organ of the circulatory system. Consists of two halves, each of which includes an atrium and a ventricle.

The retina is the inner layer of the eye, which contains light-sensitive receptors - rods and cones.

The sympathetic nervous system is a department of the autonomic nervous system, including nerve cells of the thoracic and upper lumbar spinal cord and nerve cells of the border sympathetic trunk, solar plexus, mesenteric nodes, the processes of which innervate all organs. The sympathetic nervous system is involved in the regulation of a number of body functions: impulses are carried through its fibers, causing increased metabolism, increased heart rate, constriction of blood vessels, dilation of the pupils, etc.

A synapse is a zone of functional contact between neurons and other formations.

Systole is the contraction of the atria or ventricles of the heart.

The sclera is the outer opaque membrane that covers the eyeball and passes into the transparent cornea at the front of the eye. Performs protective and shaping functions.

Hearing analyzer - carries out the perception and analysis of sounds. Consists of the inner, middle and outer ear.

Salivary glands are exocrine glands that open into the oral cavity and produce saliva.

Contractility is the property of muscle fibers to change their shape and size - to perform a motor function.

The somatic nervous system is part of the peripheral nervous system that innervates the musculoskeletal system and skin.

Sperm is produced by the male gonads. Consists of the first

matozoids (male reproductive cells) and seminal fluid, which ensures their mobility.

The middle ear is a section of the hearing organ, consisting of a tympanic cavity filled with air and three auditory ossicles - the malleus, the incus and the stapes. Separated from the external auditory canal by the eardrum.

The vitreous body is a gelatinous mass that fills the cavity of the eye. It is part of the optical system of the eye.

A joint is a movable connection of bones that allows the bones to move in different planes. There are uniaxial (flexion-extension only), biaxial (also adduction and abduction) and triaxial (rotation) joints.

Thermoregulation is the regulation of the processes of heat formation and release in the body.

Tissue fluid is one of the components of the internal environment of the body. Fills intercellular spaces in tissues and organs of animals and humans. Serves as a medium for cells from which they absorb nutrients and into which they release metabolic products.

Inhibition is an active physiological process manifested in the cessation or weakening of current activity. Along with stimulation, it ensures coordinated functioning of all organs and systems.

The trachea is a part of the respiratory tract located between the larynx and bronchi. Consists of cartilaginous half-rings connected by ligaments. Branches into two bronchi.

Platelets (red blood platelets) are the formed elements of blood involved in coagulation.

Conditioned reflexes are reflexes developed under certain conditions (hence the name) during the life of an animal and a person. They are formed on the basis of unconditioned reflexes.

Phagocytes are leukocytes capable of capturing and digesting foreign bodies (phagocytosis). Participate in the development of immunity.

Enzymes are biological catalysts, substances of protein nature.

Fibrin is an insoluble protein formed from fibrinogen during blood clotting.

Fibrinogen is a soluble protein that is constantly present in the blood. Capable of turning into fibrin.

Formed elements of blood - erythrocytes, leukocytes, platelets.

Photoreceptors - rods and cones of the retina - are light-sensitive formations that convert light energy into nerve impulses.

The lens is a structure of the eye that looks like a biconvex lens and is located behind the iris. It is part of the optical system of the eye. Provides refraction and focusing of light rays on the retina.

The central nervous system (CNS) is the main part of the nervous system, represented by the spinal cord and brain.

A suture is a method of fixed connection of bones, in which numerous protrusions of one bone fit into the corresponding depressions of another (for example, the bones of the skull).

The thyroid gland is an endocrine gland that secretes hormones that affect the growth and development of the body, as well as the intensity of metabolism.

Embryo is the embryo of animals and humans.

Endocrine glands are endocrine glands that do not have excretory ducts and secrete hormones directly into the blood (epiphysis, pituitary gland, thyroid gland, parathyroid glands, thymus gland, adrenal glands, etc.). Hormones secreted by endocrine glands are involved in the neurohumoral regulation of body functions.

The epidermis is the outer layer of the skin.

Epithelium is a layer of closely spaced cells covering the surface of the body (for example, skin), lining all its cavities and performing mainly protective, excretory and absorption functions. Most glands also consist of epithelium.

Erythrocytes are red blood cells containing hemoglobin. They carry oxygen from the lungs to the tissues and carbon dioxide in the opposite direction. Human red blood cells do not have a nucleus.

The ovaries are a paired female reproductive gland in which eggs (female reproductive cells) are formed and mature. The ovaries are located in the abdominal cavity and produce hormones - estrogens and progesterone.

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Dictionary of basic biological terms and concepts

A

ABIOTIC ENVIRONMENT - a set of inorganic conditions (factors) for the habitat of organisms. These include the composition of atmospheric air, the composition of sea and fresh waters, soils, air and soil temperatures, lighting and other factors.

AGROBIOCENOSIS - a set of organisms living on lands occupied by crops and plantings of agricultural crops. In Africa, the vegetation cover is created by man and usually consists of one or two cultivated plants and accompanying weeds.

AGROECOLOGY is a branch of ecology that studies the patterns of organization of artificial plant communities, their structure and functioning.

NITROGEN FIXING BACTERIA - bacteria capable of assimilating nitrogen from the air to form nitrogen compounds available for use by other organisms. Among A.b. there are both freely living in the soil and coexisting with mutual benefit with the roots of higher plants.

ANTIBIOTICS are specific chemical substances produced by microorganisms and capable, even in small quantities, of exerting a selective effect on other microorganisms and malignant tumor cells. In a broad sense, A. also includes antimicrobial substances in the tissues of higher plants (phytoncides). The first A. was obtained in 1929 by Fleming (although penicillium was used by Russian doctors much earlier). The term "A." proposed in 1942 by Z. Waksman.

ANTHROPOGENIC FACTORS - factors of human influence on the environment. Human influence on plants can be both positive (plant cultivation, pest control, protection of rare species and biocenoses) and negative. The negative impact of humans can be direct - deforestation, collection of flowering plants, trampling of vegetation in parks and forests, indirect - through environmental pollution, destruction of pollinating insects, etc.

B

BACTERIA is the kingdom of living organisms. They differ from organisms of other kingdoms in their cell structure. Single-celled or grouped microorganisms. Fixed or mobile - with flagella.

BACTERICIDALITY - the ability of plant juices, animal blood serum and some chemicals to kill bacteria.

BIOINDICATORS - organisms whose developmental features or quantity serve as indicators of natural processes or anthropogenic changes in the environment. Many organisms can exist only within certain, often narrow limits of changes in environmental factors (chemical composition of soil, water, atmosphere, climatic and weather conditions, the presence of other organisms). For example, lichens and some conifers serve to maintain air purity. Aquatic plants, their species composition and numbers determine the degree of water pollution.

BIOMASS - the total mass of individuals of a species, group of species or community of organisms. It is usually expressed in units of mass (grams, kilograms) per unit area or volume of habitat (hectare, cubic meter). About 90% of the entire biosphere consists of terrestrial plants. The rest is accounted for by aquatic vegetation.

BIOSPHERE is the area of ​​distribution of life on Earth, the composition, structure and energy of which are determined by the joint activity of living organisms.

BIOCENOSIS is a set of plants and animals formed in the process of evolutionary development in the food chain, influencing each other during the struggle for existence and natural selection (plants, animals and microorganisms inhabiting a lake, river valley, pine forest).

IN

SPECIES is the basic unit in the taxonomy of living organisms. A set of individuals that have a number of common characteristics and are capable of interbreeding to form fertile offspring, inhabiting a certain territory.

GERMINATION - the ability of seeds to produce normal seedlings within a specified period under certain conditions. Germination is expressed as a percentage.

HIGHER PLANTS are complex multicellular organisms with well-defined vegetative organs, adapted, as a rule, to life in a terrestrial environment.

G

GAMETE - sex cell. Ensures the transmission of hereditary information from parents to descendants.

GAMETOPHYTE - the sexual generation in the life cycle of plants that develop with alternating generations. Formed from a spore, produces gametes. In higher plants, the plant is represented only by mosses as leaf-stemmed plants. In others it is poorly developed and short-lived. In mosses, horsetails, and ferns, G. is a prothallus that produces both male and female gametes. In angiosperms, the female embryo is the embryo sac, and the male is pollen. They grow along river banks, in swamps and wet fields (reed, cattail).

GENERATIVE ORGANS - organs that perform the function of sexual reproduction. Flowering plants have flowers and fruits, or more precisely, a speck of dust and an embryo sac.

HYBRIDIZATION - combining the hereditary material of different cells into one. In agriculture, crossing different varieties of plants. See also Selection.

HYGROPHYTES - plants of humid habitats. They grow in swamps, in water, and in tropical rainforests. Their root system is poorly developed. Wood and mechanical tissues are poorly developed. Can absorb moisture over the entire surface of the body.

HYDROPHYTES - aquatic plants attached to the ground and immersed in water only with the lower part. Unlike hygrophytes, they have well-developed conductive and mechanical tissues and a root system. But there are many intercellular spaces and air cavities.

GLYCOGEN - carbohydrate, polysaccharide. Its branched molecules are built from glucose residues. Energy reserve of many living organisms. When it breaks down, glucose (sugar) is formed and energy is released. Found in the liver and muscles of vertebrates, in fungi (yeast), in algae, and in the grain of some varieties of corn.

GLUCOSE - grape sugar, one of the most common simple sugars. In green plants, it is formed from carbon dioxide and water as a result of photosynthesis. Participates in many metabolic reactions.

Gynosperms are the most ancient of seed plants. Most are evergreen trees and shrubs. Representatives of gymnosperms are conifers (spruce, pine, cedar, fir, larch).

MUSHROOMS are the kingdom of living organisms. They combine the characteristics of both plants and animals, and also have special characteristics. There are both unicellular and multicellular fungi. The body (mycelium) consists of a system of branching threads.

HUMUS (HUMUS) is a complex of specific dark-colored organic soil substances. Obtained as a result of the transformation of organic residues. To a large extent determines soil fertility.

The first task corresponds to the first section in the codifier, which can be easily found on the FIPI website.

The section is called “Biology as a Science. Methods of scientific knowledge". What does this mean? There are no specifics here, so, in fact, he can include anything.

In the codifier you can find a list of content elements tested on the Unified State Exam. That is, everything you need to know to successfully complete the task is listed there. For correct execution you can get 1 point.

We present them below for your reference:

1. Biology as a science, its achievements, methods of knowing living nature.
2. The role of biology in the formation of the modern natural science picture of the world.
3. Level organization and evolution. The main levels of organization of living nature: cellular, organismal, population-species, biogeocenotic, biosphere.
4. Biological systems. General characteristics of biological systems: cellular structure, features of chemical composition, metabolism and energy conversion, homeostasis, irritability, movement, growth and development, reproduction, evolution.

It looks very complicated and unclear, however, during the preparation process you will still become familiar with all these topics; they do not need to be taught for a separate task.

Analysis of typical tasks No. 1 of the Unified State Exam in biology

Having looked through all the tasks offered by the open bank, you can distinguish two classifications of tasks: by thematic section and by the form of the question.

By thematic section

If you arrange them in order from most to least, you get:

• Botany
• human anatomy
• Cytology
• General biology
• Genetics
• Evolution

Let's look at examples of tasks for each section.

Botany

Consider the proposed structure of the organs of a flowering plant. Write down the missing term in your answer, indicated by a question mark in the diagram.

The stem, buds and leaves together make up the above-ground part of the plant - the shoot

Answer: escape.

human anatomy

Consider the proposed diagram of the structure of the skeleton of the upper limb. Write down the missing term in your answer, indicated by a question mark in the diagram.

The free upper limb includes the hand. If you don’t go into details about the bones that make it up yet, then you just need to remember three sections: shoulder, forearm, hand.

The shoulder begins at the shoulder joint and ends at the elbow joint.

The forearm, accordingly, should end with the elbow, and start from the wrist inclusive.

The hand is the bones that make up the palm and phalanges of the fingers.

Answer: shoulder.

Cytology

First, you need to familiarize yourself with the concept of “cytology” in order to understand what we are talking about.

Cytology is a branch of biology that studies living cells, their organelles, their structure, functioning, processes of cell reproduction, aging and death. The terms cell biology and cell biology are also used.

The word “cytology” includes two roots from the Greek language: “cytos” - cell, “logos” - science, as in biology - “bio” - living, “logos” - science. Knowing the roots, you can easily assemble a definition.

Consider the proposed classification scheme for organelles. Write down the missing term in your answer, indicated by a question mark in the diagram.

From this diagram it becomes clear that organelles are divided into three types according to the number of membranes. Here, only one window is allocated for each type, but this does not mean that only one organelle corresponds to each type. In addition, plant and animal cells have differences in cell structure.

Plants, unlike animals, have:

• Cellulose cell wall
• Chloroplasts required for photosynthesis
• Large digestive vacuole. The older the cell, the larger the vacuole

Organelles are divided according to the number of membranes:

• Single-membrane organelles: endoplasmic reticulum, Golgi complex, lysosomes.
• Double-membrane organelles: nucleus, mitochondria, plastids (leukoplasts, chloroplasts, chromoplasts).
• Non-membrane organelles: ribosomes, centrioles, nucleolus.

In the diagram, the question is about double-membrane organelles. We know that mitochondria and plastids are double-membrane. We reason: there is only one pass, but two options. It's not just like that. You need to re-read the question carefully. There are two types of cells, but we are not told which one we are talking about, which means the answer must be universal. Plastids are characteristic only of plant cells, therefore, mitochondria remain.

Answer: mitochondria, or mitochondrion.

(The open jar shows both options)

Genetics

Again, let's look at the definition:

Genetics is the science of the laws of heredity and variability.

Let's break the definition down into definitions:

Heredity is the set of natural properties of an organism received from parents and predecessors.

Variability is the variety of characteristics among representatives of a given species, as well as the ability of descendants to acquire differences from their parent forms.

Consider the proposed classification scheme for types of variability. Write down the missing term in your answer, indicated by a question mark in the diagram.

Since the concept of variability includes the property of acquiring differences from parental forms, this gives us the term “heredity.” A healthy person has 46 chromosomes. 23 come from mom, 23 from dad. This means that a child is a combination of traits acquired from his parents, moreover, mom and dad also carry the traits of their parents in their genetic code. During the rearrangements, some appear in the offspring, while others can simply be transferred to the genome. Those that have appeared are dominant, and those that are simply written in the genome are recessive. Such variability does not bring about major changes against the background of the whole species.

Answer: combinative.

Evolution

Evolution in biology is the irreversible historical development of living nature.

It is aimed at the survival of the species. One should not think that evolution is only a complication of the organism; some species have taken the path of degeneration, that is, simplification, in order to survive.

Biological regression obviously has no options. Those who came to regression were unable to adapt to changing environmental conditions, which means they became extinct. Biologists know that it is not the fittest that survives, but the fittest.

Biological progress has three paths, let's start with a simple one:

Adaptation is the main goal. Another way to say “adapt” is “adapt.”

The next path is idioadaptation.

Idioadaptation is the acquisition of useful characteristics for life.

Or in scientific terms: Idioadaptation is a direction of evolution consisting in the acquisition of new characteristics while maintaining the level of organization of ancestral forms.

Everyone knows what an anteater looks like. He has an elongated muzzle, and all this is needed in order to get his food - small insects. This change in the shape of the muzzle did not make fundamental changes in the life of anteaters, but it became more convenient for them to eat than their ancestors with a less elongated muzzle.

Aromorphosis is the emergence during evolution of characteristics that significantly increase the level of organization of living organisms.

For example, the emergence of angiosperms greatly increased survival rates.

Answer: idioadaptation.

So, we have analyzed one example of tasks from different sections asked in the first task.

Second classification: by form the question asked. Although in the first task there are diagrams everywhere, the question can still be posed in different ways.

Question forms

1.Missed term in the diagram

You just need to enter the term missing in the diagram, as in the tasks above. These are the majority of questions.

Consider the proposed scheme of evolutionary directions. Write down the missing term in your answer, indicated by a question mark in the diagram.

We discussed this option above, so we are writing the answer right away.

Answer: idioadaptation.

2. Answer to the question from the diagram

The diagram is complete, based on your knowledge you need to answer the question according to the diagram.

Look at the picture with examples of chromosomal mutations. The number 3 on it indicates a chromosomal rearrangement... (write down the term in your answer)

There are several types of chromosomal rearrangements that you need to know:

Duplication is a type of chromosomal rearrangement in which a section of a chromosome is doubled.

Deletions are the loss of a section of a chromosome.

Inversion is a change in the structure of a chromosome caused by a 180° rotation of one of its internal sections.

Translocation is the transfer of a section of a chromosome to another.

The third picture clearly shows that there are more chromosome sections. The first four sections of the chromosome doubled, there were 9 of them, instead of 5, as before. This means that a part of the chromosome has been duplicated.

Answer: duplication.

3. Answer to the question regarding the circuit part

The diagram is complete, but I have a question regarding some part of it:

Consider the proposed reaction scheme between amino acids. Write down in your answer the concept denoting the name of the chemical bond marked in the diagram with a question mark.

This diagram shows the reaction between two amino acids, as is known from the question. Peptide bonds act between them. You will become more familiar with them when studying DNA and RNA.

A peptide bond is a chemical bond formed between two molecules as a result of a condensation reaction between the carboxyl group (-COOH) of one molecule and the amino group (-NH2) of another molecule, releasing one molecule of water (H2O).

Answer: peptide, or peptide bond.

According to FIPI, the first task is basic, so it does not pose any particular difficulty for the graduate. It covers a lot of topics, but is rather superficial. After studying all the topics, it is better to look through all the available diagrams for this task, since the answer is not always obvious. And do not forget to read the question carefully, it is not always the same.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

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1. What does anatomy study?

Human anatomy is the science of the form, structure and development of the human body in accordance with gender, age and individual characteristics.

Anatomy studies the external forms and proportions of the human body and its parts, individual organs, their design, and microscopic structure. The tasks of anatomy include the study of the main stages of human development in the process of evolution, the structural features of the body and individual organs at various age periods, as well as in environmental conditions.

2. What does physiology study?

Physiology - (from the Greek physis - nature and logos - word, doctrine), the science of life processes and the mechanisms of their regulation in the human body. Physiology studies the mechanisms of various functions of a living organism (growth, reproduction, respiration, etc.), their relationship with each other, regulation and adaptation to the external environment, origin and formation in the process of evolution and individual development of the individual. While solving fundamentally common problems, the physiology of animals and humans and the physiology of plants have differences due to the structure and functions of their objects. Thus, for the physiology of animals and humans, one of the main tasks is the study of the regulatory and integrating role of the nervous system in the body. Prominent physiologists (I.M. Sechenov, N.E. Vvedensky, I.P. Pavlov, A.A. Ukhtomsky, G. Helmholtz, C. Bernard, C. Sherrington, etc.) participated in solving this problem. Plant physiology, which emerged from botany in the 19th century, traditionally studies mineral (root) and aerial (photosynthesis) nutrition, flowering, fruiting, etc. It serves as the theoretical basis of plant growing and agronomy. The founders of Russian plant physiology - A.S. Famintsyn and K.A. Timiryazev. Physiology is related to anatomy, cytology, embryology, biochemistry and other biological sciences.

3. What does hygiene study?

Hygiene - (from the ancient Greek ?gyainYu “healthy”, from?gYaeib “health”) - the science of the influence of the environment on human health.

As a result, hygiene has two objects of study - environmental factors and the body's reaction, and uses the knowledge and methods of physics, chemistry, biology, geography, hydrogeology and other sciences that study the environment, as well as physiology, anatomy and pathophysiology.

Environmental factors are varied and are divided into:

· Physical - noise, vibration, electromagnetic and radioactive radiation, climate, etc.

· Chemical - chemical elements and their compounds.

· Factors of human activity - daily routine, severity and intensity of work, etc.

· Social.

Within the framework of hygiene, the following main sections are distinguished:

· Environmental hygiene - studying the impact of natural factors - atmospheric air, solar radiation, etc.

· Occupational health - studying the impact of the production environment and factors of the production process on humans.

· Communal hygiene - within the framework of which requirements for urban planning, housing, water supply, etc. are developed.

· Food hygiene - studying the meaning and impact of food, developing measures to optimize and ensure food safety (this section is often confused with dietetics).

· Hygiene of children and adolescents - studying the complex effects of factors on a growing organism.

· Military hygiene - aimed at preserving and increasing the combat effectiveness of personnel.

· Personal hygiene is a set of hygienic rules, the implementation of which contributes to the preservation and strengthening of health.

Also some narrow sections: radiation hygiene, industrial toxicology, etc.

Main tasks of hygiene:

· study of the influence of the external environment on the health and performance of people. At the same time, the external environment should be understood as the entire complex complex of natural, social, everyday, production and other factors.

· scientific substantiation and development of hygienic standards, rules and measures to improve the health of the external environment and eliminate harmful factors;

· scientific substantiation and development of hygienic standards, rules and measures to increase the body’s resistance to possible harmful environmental influences in order to improve health and physical development, and increase performance. This is facilitated by a balanced diet, physical exercise, hardening, a properly organized work and rest schedule, and adherence to personal hygiene rules.

4. What factors that disrupt the balance between the environment and the body include toxins?

Each person’s body contains a certain amount of harmful substances, which are called toxins (from the Greek toxikon - poison). They are divided into two large groups.

Exotoxins are harmful substances of chemical and natural origin that enter the body from the external environment with food, air or water. Most often these are nitrates, nitrites, heavy metals and many other chemical compounds present in almost everything that surrounds us. Living in large industrial cities, working in hazardous industries, and even taking medications containing toxic substances are all, to one degree or another, factors in poisoning the body.

Endotoxins are harmful substances that are formed during the life of the body. There are especially many of them in various diseases and metabolic disorders, in particular in poor bowel function, abnormal liver function, sore throat, pharyngitis, influenza, acute respiratory infections, kidney diseases, allergic conditions, even stress.

Toxins poison the body and disrupt its coordinated functioning - most often they undermine the immune, hormonal, cardiovascular and metabolic systems. This leads to complications in the course of various diseases and hinders recovery. Toxins lead to a decrease in the body's resistance, deterioration of general condition and loss of strength.

One theory of aging suggests that it is caused by the accumulation of toxins in the body. They inhibit the functioning of organs, tissues, cells, and disrupt the flow of biochemical processes in them. This ultimately leads to a deterioration in their functions and, as a consequence, to the aging of the entire organism.

Almost any disease is much easier and easier to treat if toxins do not accumulate and are quickly eliminated from the body.

Nature has endowed humans with various systems and organs capable of destroying, neutralizing and removing harmful substances from the body. These are, in particular, the systems of the liver, kidneys, lungs, skin, gastrointestinal tract, etc. In modern conditions, it is becoming increasingly difficult to cope with aggressive toxins, and a person needs additional reliable and effective help.

5. What factors does radiation relate to?

Radioactivity is the instability of the nuclei of some atoms, which manifests itself in their ability to undergo spontaneous transformation (in scientific terms, decay), which is accompanied by the release of ionizing radiation (radiation). The energy of such radiation is quite high, so it is capable of influencing matter, creating new ions of different signs. It is impossible to cause radiation using chemical reactions; it is a completely physical process.

There are several types of radiation:

· Alpha particles are relatively heavy particles, positively charged, and are helium nuclei.

· Beta particles are ordinary electrons.

· Gamma radiation - has the same nature as visible light, but has a much greater penetrating ability.

· Neutrons are electrically neutral particles that arise mainly near an operating nuclear reactor; access there must be limited.

· X-rays are similar to gamma rays, but have less energy. By the way, the Sun is one of the natural sources of such rays, but protection from solar radiation is provided by the Earth’s atmosphere.

Sources of radiation are nuclear installations (particle accelerators, reactors, X-ray equipment) and radioactive substances. They can exist for a considerable time without manifesting themselves in any way, and you may not even suspect that you are near an object of extreme radioactivity.

The body reacts to the radiation itself, and not to its source. Radioactive substances can enter the body through the intestines (with food and water), through the lungs (during breathing) and even through the skin during medical diagnostics using radioisotopes. In this case, internal exposure occurs. In addition, external radiation has a significant impact on the human body, i.e. The source of radiation is outside the body. The most dangerous, of course, is internal radiation.

The effect of radiation on the human body is called irradiation. During this process, radiation energy is transferred to the cells, destroying them. Radiation can cause all sorts of diseases: infectious complications, metabolic disorders, malignant tumors and leukemia, infertility, cataracts and much more. Radiation has a particularly acute effect on dividing cells, so it is especially dangerous for children.

Radiation refers to those factors of physiological impact on the human body for which the human body does not have receptors. He is simply unable to see, hear, touch or taste it.

The absence of direct cause-and-effect relationships between radiation and the body’s response to its effects allows us to constantly and quite successfully exploit the idea of ​​​​the danger of the influence of small doses on human health.

6. What factors include viruses?

Viruses (derived from the Latin virus - “poison”) are the smallest microorganisms that do not have a cellular structure, a protein synthesizing system and are capable of reproducing only in the cells of highly organized life forms. It was first used to designate an agent capable of causing an infectious disease in 1728.

The appearance of viruses on the evolutionary tree of life is unclear: some may have evolved from plasmids, small DNA molecules that can be passed from one cell to another, while others may have originated from bacteria. In evolution, viruses are an important means of horizontal gene transfer, causing genetic diversity.

Viruses spread in many ways: plant viruses are often transmitted from plant to plant by insects that feed on plant sap, such as aphids; Animal viruses can be spread by blood-sucking insects, such organisms are known as vectors. The influenza virus is spread through respiratory droplets from coughing and sneezing. Norovirus and rotavirus, which commonly cause viral gastroenteritis, are transmitted through the fecal-oral route through contact with contaminated food or water. HIV is one of several viruses that are transmitted through sexual contact and through contaminated blood transfusions. Each virus has a specific host specificity, determined by the types of cells it can infect. The host range may be narrow or, if the virus affects many species, wide.

Viruses, although very small and impossible to see, are the subject of scientific study:

For physicians, viruses are the most common causative agents of infectious diseases: influenza, measles, smallpox, tropical fevers.

For a pathologist, viruses are the etiological agents (cause) of cancer and leukemia, the most common and dangerous pathological processes.

For a veterinarian, viruses are the culprits of epizootics (mass diseases) of foot-and-mouth disease, avian plague, infectious anemia and other diseases affecting farm animals.

For an agronomist, viruses are the causative agents of spotted stripe of wheat, tobacco mosaic, yellow dwarf of potatoes and other diseases of agricultural plants.

For the florist, viruses are the factors that cause the amazing colors of tulips to appear.

For the medical microbiologist, viruses are agents that cause the appearance of toxic (poisonous) varieties of diphtheria or other bacteria, or factors that contribute to the development of bacteria resistant to antibiotics.

For an industrial microbiologist, viruses are pests of bacteria, producers, antibiotics and enzymes.

For a geneticist, viruses are carriers of genetic information.

For a Darwinist, viruses are important factors in the evolution of the organic world.

For an ecologist, viruses are factors involved in the formation of related systems of the organic world.

For a biologist, viruses are the simplest forms of life, possessing all its main manifestations.

For a philosopher, viruses are the clearest illustration of the dialectics of nature, a touchstone for polishing such concepts as living and nonliving, part and whole, form and function.

Viruses are the causative agents of the most important diseases of humans, farm animals and plants, and their importance is increasing all the time as the incidence of bacterial, protozoal and fungal diseases decreases.

7. What is homeostasis?

Life is possible only with a relatively small range of deviations of various characteristics of the internal environment - physico-chemical (acidity, osmotic pressure, temperature, etc.) and physiological (blood pressure, blood sugar, etc.) - from a certain average value. The constancy of the internal environment of a living organism is called homeostasis (from the Greek words homoios - similar, identical and stasis - state).

Under the influence of environmental factors, vital characteristics of the internal environment can change. Then reactions occur in the body aimed at restoring them or preventing such changes. These reactions are called homeostatic. When blood is lost, for example, vasoconstriction occurs, preventing a drop in blood pressure. When sugar consumption increases during physical activity, its release into the blood from the liver increases, which prevents blood sugar levels from falling. With an increase in heat production in the body, the skin vessels dilate, and therefore heat transfer increases, which prevents the body from overheating.

Homeostatic reactions are organized by the central nervous system, which regulates the activity of the autonomic and endocrine systems. The latter already directly affect the tone of blood vessels, metabolic rate, and the functioning of the heart and other organs. The mechanisms of the same homeostatic reaction and their effectiveness can be different and depend on many factors, including hereditary ones.

Homeostasis is also called the preservation of constancy of the species composition and number of individuals in biocenoses, the ability of a population to maintain a dynamic balance of genetic composition, which ensures its maximum viability (genetic homeostasis).

8. What is a cytolemma?

The cytolemma is the universal skin of the cell; it performs barrier, protective, receptor, and excretory functions, transports nutrients, transmits nerve impulses and hormones, and connects cells into tissues.

This is the thickest (10 nm) and most complexly organized cell membrane. It is based on a universal biological membrane, covered on the outside with a glycocalyx, and on the inside, on the cytoplasm side, with a submembrane layer. The glycocalyx (3-4 nm thick) is represented by the outer, carbohydrate regions of complex proteins - glycoproteins and glycolipids that make up the membrane. These carbohydrate chains play the role of receptors that ensure that the cell recognizes neighboring cells and intercellular substance and interacts with them. This layer also includes surface and semi-integral proteins, the functional regions of which are located in the supramembrane zone (for example, immunoglobulins). The glycocalyx contains histocompatibility receptors, receptors for many hormones and neurotransmitters.

The submembrane, cortical layer is formed by microtubules, microfibrils and contractile microfilaments, which are part of the cell cytoskeleton. The submembrane layer maintains the shape of the cell, creates its elasticity, and ensures changes in the cell surface. Due to this, the cell participates in endo- and exocytosis, secretion, and movement.

The cytolemma performs many functions:

1) delimiting (the cytolemma separates, delimits the cell from the environment and ensures its connection with the external environment);

2) recognition by this cell of other cells and attachment to them;

3) recognition by the cell of the intercellular substance and attachment to its elements (fibers, basement membrane);

4) transport of substances and particles into and out of the cytoplasm;

5) interaction with signaling molecules (hormones, mediators, cytokines) due to the presence of specific receptors for them on its surface;

6) ensures cell movement (formation of pseudopodia) due to the connection of the cytolemma with the contractile elements of the cytoskeleton.

The cytolemma contains numerous receptors through which biologically active substances (ligands, signaling molecules, first messengers: hormones, mediators, growth factors) act on the cell. Receptors are genetically determined macromolecular sensors (proteins, glyco- and lipoproteins) built into the cytolemma or located inside the cell and specialized in the perception of specific signals of a chemical or physical nature. Biologically active substances, when interacting with a receptor, cause a cascade of biochemical changes in the cell, transforming into a specific physiological response (change in cell function).

All receptors have a general structural plan and consist of three parts: 1) supramembrane, which interacts with the substance (ligand); 2) intramembrane, carrying out signal transfer and 3) intracellular, immersed in the cytoplasm.

9. What is the significance of the nucleus?

The nucleus is an essential component of the cell (exception: mature red blood cells), where the bulk of the DNA is concentrated.

Two important processes take place in the nucleus. The first of them is the synthesis of the genetic material itself, during which the amount of DNA in the nucleus doubles (for DNA and RNA, see Nucleic acids). This process is necessary so that during subsequent cell division (mitosis) the two daughter cells end up with the same amount of genetic material. The second process is transcription - the production of all types of RNA molecules, which, migrating into the cytoplasm, provide the synthesis of proteins necessary for the life of the cell.

The nucleus differs from the surrounding cytoplasm in its refractive index. That is why it can be seen in a living cell, but usually special dyes are used to identify and study the nucleus. The Russian name “nucleus” reflects the spherical shape most characteristic of this organelle. Such nuclei can be seen in liver cells and nerve cells, but in smooth muscle and epithelial cells the nuclei are oval. There are kernels of more bizarre shapes.

The nuclei that are most dissimilar in shape consist of the same components, i.e. have a general structure plan. In the nucleus there are: nuclear envelope, chromatin (chromosomal material), nucleolus and nuclear juice. Each nuclear component has its own structure, composition and function.

The nuclear envelope includes two membranes located at some distance from each other. The space between the membranes of the nuclear envelope is called perinuclear. There are holes in the nuclear membrane - pores. But they are not end-to-end, but filled with special protein structures called the nuclear pore complex. Through pores, RNA molecules exit the nucleus into the cytoplasm, and proteins move towards them into the nucleus. The nuclear envelope membranes themselves ensure the diffusion of low-molecular compounds in both directions.

Chromatin (from the Greek word chroma - color, paint) is the substance of chromosomes, which in the interphase nucleus are much less compact than during mitosis. When cells are stained, they are painted brighter than other structures.

In the nuclei of living cells, the nucleolus is clearly visible. It has the appearance of a round or irregularly shaped body and clearly stands out against the background of a rather homogeneous nucleus. The nucleolus is a formation that occurs in the nucleus on those chromosomes that are involved in the synthesis of ribosomal RNA. The region of the chromosome that forms the nucleolus is called the nucleolar organizer. Not only RNA synthesis occurs in the nucleolus, but also the assembly of ribosomal subparticles. The number of nucleoli and their sizes may vary. The products of the activity of chromatin and the nucleolus initially enter the nuclear sap (karyoplasm).

For cell growth and reproduction, the nucleus is absolutely necessary. If the main part of the cytoplasm is experimentally separated from the nucleus, then this cytoplasmic lump (cyplast) can exist without a nucleus for only a few days. The nucleus, surrounded by the narrowest rim of cytoplasm (karyoplast), completely retains its viability, gradually ensuring the restoration of organelles and the normal volume of cytoplasm. However, some specialized cells, such as mammalian red blood cells, function for a long time without a nucleus. It is also deprived of platelets - blood platelets, formed as fragments of the cytoplasm of large cells - megakaryocytes. Sperm have a nucleus, but it is completely inactive.

10. What is fertilization?

Fertilization is the fusion of a male reproductive cell (sperm) with a female (ovum), leading to the formation of a zygote, which gives rise to a new organism. Fertilization is preceded by complex processes of maturation of the egg (oogenesis) and sperm (spermatogenesis). Unlike sperm, the egg does not have independent mobility. A mature egg leaves the follicle into the abdominal cavity in the middle of the menstrual cycle at the time of ovulation and enters the fallopian tube thanks to its suction peristaltic movements and the flickering of cilia. The period of ovulation and the first 12-24 hours. after it they are most favorable for fertilization. If it does not happen, then in the following days regression and death of the egg occurs.

During sexual intercourse, sperm (seminal fluid) enters the woman's vagina. Under the influence of the acidic environment of the vagina, some sperm die. The most viable of them penetrate through the cervical canal into the alkaline environment of its cavity and 1.5-2 hours after sexual intercourse reach the fallopian tubes, in the ampullary section of which fertilization occurs. Many sperm rush towards the mature egg, but, as a rule, only one of them penetrates through the zona pellucida covering it, the nucleus of which merges with the nucleus of the egg. From the moment the germ cells merge, pregnancy begins. A single-celled embryo is formed, a qualitatively new cell - a zygote, from which, as a result of a complex development process during pregnancy, the human body is formed. The sex of the unborn child depends on what type of sperm was fertilized in the egg, which is always the carrier of the X chromosome. If the egg was fertilized by a sperm with an X (female) sex chromosome, a female embryo (XX) is created. When an egg is fertilized by a sperm with a Y (male) sex chromosome, a male embryo (XY) develops. There is evidence that sperm containing the Y chromosome are less durable and die faster than sperm containing the X chromosome. Obviously, in this regard, the likelihood of conceiving a boy increases if fertilizing sexual intercourse occurs during ovulation. If sexual intercourse took place several days before ovulation, there is a greater chance that fertilization will occur. Eggs contain sperm containing the X chromosome, i.e. there is a higher chance of having a girl.

The fertilized egg, moving along the fallopian tube, undergoes crushing, passes through the stages of blastula, morula, blastocyst and reaches the uterine cavity on the 5-6th day from the moment of fertilization. At this point, the embryo (embryoblast) is covered on the outside with a layer of special cells - trophoblast, which provides nutrition and implantation (incorporation) into the uterine mucosa, called decidual during pregnancy. The trophoblast secretes enzymes that dissolve the uterine lining, which facilitates the immersion of the fertilized egg into its thickness.

11. What characterizes the crushing stage?

Cleavage is a series of rapid divisions of the zygote without intermediate growth.

After combining the genomes of the egg and sperm, the zygote immediately begins mitotic division - the development of a multicellular diploid organism begins. The first stage of this development is called cleavage. It has a number of features. First of all, in most cases, cell division does not alternate with cell growth. The number of cells of the embryo increases, but its total volume remains approximately equal to the volume of the zygote. During cleavage, the volume of the cytoplasm remains approximately constant, but the number of nuclei, their total volume, and especially the surface area increase. This means that during the period of fragmentation, normal (i.e., characteristic of somatic cells) nuclear-plasma relations are restored. During cleavage, mitoses follow one another especially quickly. This occurs due to the shortening of the interphase: the Gx period is completely eliminated, and the G2 period is also shortened. Interphase practically boils down to the S-period: as soon as the entire DNA is doubled, the cell enters mitosis.

The cells formed during cleavage are called blastomeres. In many animals, they divide synchronously for quite a long time. True, sometimes this synchrony is broken early: for example, in roundworms at the stage of four blastomeres, and in mammals the first two blastomeres divide asynchronously. In this case, the first two divisions usually occur in the meridian planes (pass through the animal-vegetative axis), and the third division - in the equatorial plane (perpendicular to this axis).

Another characteristic feature of cleavage is the absence of signs of tissue differentiation in blastomeres. Cells may already “know” their future fate, but do not yet have neural, muscle or epithelial signs.

12. What is implantation?

physiology cytolemma zygote

Implantation (from Latin in (im) - in, inside and plantatio - planting, transplantation), attachment of the embryo to the wall of the uterus in mammals with intrauterine development and in humans.

There are three types of implantation:

· Central implantation - when the embryo remains in the lumen of the uterus, attaching to its wall either with the entire surface of the trophoblast, or only part of it (in chiropterans, ruminants).

· Eccentric implantation - the embryo penetrates deep into the fold of the uterine mucosa (the so-called uterine crypt), the walls of which then grow together above the embryo and form an implantation chamber isolated from the uterine cavity (in rodents).

· Interstitial implantation - characteristic of higher mammals (primates and humans) - the embryo actively destroys the cells of the uterine mucosa and penetrates into the resulting cavity; The uterine defect heals, and the embryo is completely immersed in the wall of the uterus, where its further development occurs.

13. What is gastrulation?

Gastrulation is a complex process of morphogenetic changes, accompanied by reproduction, growth, directed movement and differentiation of cells, resulting in the formation of germ layers (ectoderm, mesoderm and endoderm) - the sources of the primordia of tissues and organs. The second stage of ontogenesis after fragmentation. During gastrulation, the movement of cell masses occurs with the formation of a two-layer or three-layer embryo from the blastula - the gastrula.

The type of blastula determines the method of gastrulation.

The embryo at this stage consists of clearly separated layers of cells - germ layers: outer (ectoderm) and inner (endoderm).

In multicellular animals, except coelenterates, in parallel with gastrulation or, as in the lancelet, after it, the third germ layer appears - the mesoderm, which is a set of cellular elements located between the ectoderm and endoderm. Due to the appearance of mesoderm, the embryo becomes three-layered.

In many groups of animals, it is at the gastrulation stage that the first signs of differentiation appear. Differentiation (differentiation) is the process of the emergence and growth of structural and functional differences between individual cells and parts of the embryo.

The nervous system, sensory organs, skin epithelium, and tooth enamel are formed from the ectoderm; from the endoderm - the epithelium of the midgut, digestive glands, epithelium of the gills and lungs; from the mesoderm - muscle tissue, connective tissue, circulatory system, kidneys, gonads, etc.

In different groups of animals, the same germ layers give rise to the same organs and tissues.

Methods of gastrulation:

· Intussusception occurs by invagination of the wall of the blastula into the blastocoel; characteristic of most groups of animals.

· Delamination (characteristic of coelenterates) - cells located outside are transformed into the epithelial layer of ectoderm, and the endoderm is formed from the remaining cells. Typically, delamination is accompanied by divisions of blastula cells, the plane of which runs “tangentially” to the surface.

· Immigration - migration of individual cells of the blastula wall into the blastocoel.

· Unipolar - on one section of the blastula wall, usually at the vegetative pole;

· Multipolar - in several areas of the blastula wall.

· Epiboly - the overgrowth of some cells by rapidly dividing other cells or the overgrowth of cells by the internal mass of the yolk (with incomplete crushing).

· Involution is the turning into the embryo of an increasing in size outer layer of cells, which spreads along the inner surface of the cells remaining outside.

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