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

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

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

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

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

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

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

Ecosystem level of organization- this is the level of microecosystems, mesoecosystems, macroecosystems. At this level, types of nutrition, types of relationships between organisms and populations in the ecosystem are studied, population size, population dynamics, population density, ecosystem productivity, succession. This level studies ecology.

Also distinguished biosphere level of organization living matter. The biosphere is a gigantic ecosystem that occupies part of the geographical envelope of the Earth. This is a mega ecosystem. In the biosphere there is a circulation of substances and chemical elements, as well as the transformation of solar energy.

2. Fundamental properties of living matter

Metabolism (metabolism)

Metabolism (metabolism) is a set of chemical transformations occurring in living systems that ensure their vital activity, growth, reproduction, development, self-preservation, constant contact with the environment, and the ability to adapt to it and its changes. During the metabolic process, the molecules that make up the cells are broken down and synthesized; formation, destruction and renewal of cellular structures and intercellular substance. Metabolism is based on the interrelated processes of assimilation (anabolism) and dissimilation (catabolism). Assimilation - processes of synthesis of complex molecules from simple ones with the expenditure of energy stored during dissimilation (as well as the accumulation of energy during deposition of synthesized substances). Dissimilation is the process of breakdown (anaerobic or aerobic) of complex organic compounds, which occurs with the release of energy necessary for the functioning of the body. Unlike bodies of inanimate nature, exchange with the environment for living organisms is a condition for their existence. In this case, self-renewal occurs. Metabolic processes occurring inside the body are combined into metabolic cascades and cycles by chemical reactions that are strictly ordered in time and space. The coordinated occurrence of a large number of reactions in a small volume is achieved through the ordered distribution of individual metabolic units in the cell (the principle of compartmentalization). Metabolic processes are regulated with the help of biocatalysts - special enzyme proteins. Each enzyme has the substrate specificity to catalyze the conversion of only one substrate. This specificity is based on a kind of “recognition” of the substrate by the enzyme. Enzymatic catalysis differs from non-biological catalysis in its extremely high efficiency, as a result of which the rate of the corresponding reaction increases by 1010 - 1013 times. Each enzyme molecule is capable of performing from several thousand to several million operations per minute without being destroyed during participation in reactions. Another characteristic difference between enzymes and non-biological catalysts is that enzymes are capable of accelerating reactions under normal conditions (atmospheric pressure, body temperature, etc.). All living organisms can be divided into two groups - autotrophs and heterotrophs, differing in the sources of energy and necessary substances for their life. Autotrophs are organisms that synthesize organic compounds from inorganic substances using the energy of sunlight (photosynthetics - green plants, algae, some bacteria) or energy obtained from the oxidation of an inorganic substrate (chemosynthetics - sulfur, iron bacteria and some others). Autotrophic organisms are able to synthesize all components of the cell. The role of photosynthetic autotrophs in nature is decisive - being the primary producer of organic matter in the biosphere, they ensure the existence of all other organisms and the course of biogeochemical cycles in the cycle of substances on Earth. Heterotrophs (all animals, fungi, most bacteria, some non-chlorophyll plants) are organisms that require for their existence ready-made organic substances, which, when supplied as food, serve as both a source of energy and a necessary “building material”. A characteristic feature of heterotrophs is the presence of amphibolism, i.e. the process of formation of small organic molecules (monomers) formed during the digestion of food (the process of degradation of complex substrates). Such molecules - monomers - are used to assemble their own complex organic compounds.

Self-reproduction (reproduction)

The ability to reproduce (reproduce one’s own kind, self-reproduction) is one of the fundamental properties of living organisms. Reproduction is necessary in order to ensure the continuity of the existence of species, because The lifespan of an individual organism is limited. Reproduction more than compensates for losses caused by the natural death of individuals, and thus maintains the preservation of the species over generations of individuals. In the process of evolution of living organisms, the evolution of methods of reproduction occurred. Therefore, in the numerous and diverse species of living organisms that currently exist, we find different forms of reproduction. Many species of organisms combine several methods of reproduction. It is necessary to distinguish two fundamentally different types of reproduction of organisms - asexual (the primary and more ancient type of reproduction) and sexual. In the process of asexual reproduction, a new individual is formed from one or a group of cells (in multicellular organisms) of the maternal organism. In all forms of asexual reproduction, offspring have a genotype (set of genes) identical to the maternal one. Consequently, all the offspring of one maternal organism turn out to be genetically homogeneous and the daughter individuals have the same set of characteristics. In sexual reproduction, a new individual develops from a zygote, which is formed by the fusion of two specialized germ cells (the process of fertilization) produced by two parent organisms. The nucleus in the zygote contains a hybrid set of chromosomes, formed as a result of combining sets of chromosomes of fused gamete nuclei. In the nucleus of the zygote, a new combination of hereditary inclinations (genes), introduced equally by both parents, is thus created. And the daughter organism developing from the zygote will have a new combination of characteristics. In other words, during sexual reproduction, a combinative form of hereditary variability of organisms occurs, which ensures the adaptation of species to changing environmental conditions and represents an essential factor in evolution. This is a significant advantage of sexual reproduction compared to asexual reproduction. The ability of living organisms to reproduce themselves is based on the unique property of nucleic acids for reproduction and the phenomenon of matrix synthesis, which underlies the formation of nucleic acid and protein molecules. Self-reproduction at the molecular level determines both the implementation of metabolism in cells and the self-reproduction of the cells themselves. Cell division (cell self-reproduction) underlies the individual development of multicellular organisms and the reproduction of all organisms. The reproduction of organisms ensures the self-reproduction of all species inhabiting the Earth, which in turn determines the existence of biogeocenoses and the biosphere.

Heredity and variability

Heredity provides material continuity (the flow of genetic information) between generations of organisms. It is closely related to reproduction at the molecular, subcellular and cellular levels. Genetic information that determines the diversity of hereditary traits is encrypted in the molecular structure of DNA (in RNA for some viruses). Genes encode information about the structure of synthesized proteins, enzymatic and structural. The genetic code is a system for “recording” information about the sequence of amino acids in synthesized proteins using the sequence of nucleotides in the DNA molecule. The set of all genes of an organism is called a genotype, and the set of characteristics is called a phenotype. The phenotype depends both on the genotype and on internal and external environmental factors that affect gene activity and determine regular processes. The storage and transmission of hereditary information is carried out in all organisms with the help of nucleic acids; the genetic code is the same for all living beings on Earth, i.e. it is universal. Thanks to heredity, traits are passed on from generation to generation that ensure the adaptation of organisms to their environment. If during the reproduction of organisms only the continuity of existing characteristics and properties were manifested, then against the background of changing environmental conditions the existence of organisms would be impossible, since a necessary condition for the life of organisms is their adaptability to the conditions of their environment. There is variability in the diversity of organisms belonging to the same species. Variability can occur in individual organisms during their individual development or within a group of organisms over a series of generations during reproduction. There are two main forms of variability, differing in the mechanisms of occurrence, the nature of changes in characteristics and, finally, their significance for the existence of living organisms - genotypic (hereditary) and modification (non-hereditary). Genotypic variability is associated with a change in the genotype and leads to a change in phenotype. Genotypic variability may be based on mutations (mutational variability) or new combinations of genes that arise during the process of fertilization during sexual reproduction. In the mutational form, changes are associated primarily with errors during the replication of nucleic acids. Thus, new genes appear that carry new genetic information; new signs appear. And if newly emerging characters are useful to the organism in specific conditions, then they are “picked up” and “fixed” by natural selection. Thus, the adaptability of organisms to environmental conditions, the diversity of organisms are based on hereditary (genotypic) variability, and the preconditions for positive evolution are created. With non-hereditary (modifying) variability, changes in the phenotype occur under the influence of environmental factors and are not associated with changes in the genotype. Modifications (changes in characteristics during modification variability) occur within the limits of the reaction norm, which is under the control of the genotype. Modifications are not passed on to subsequent generations. The significance of modification variability is that it ensures the organism's adaptability to environmental factors during its life.

Individual development of organisms

All living organisms are characterized by a process of individual development - ontogenesis. Traditionally, ontogeny is understood as the process of individual development of a multicellular organism (formed as a result of sexual reproduction) from the moment of formation of the zygote to the natural death of the individual. Due to the division of the zygote and subsequent generations of cells, a multicellular organism is formed, consisting of a huge number of different types of cells, various tissues and organs. The development of an organism is based on a “genetic program” (embedded in the genes of the chromosomes of the zygote) and is carried out under specific environmental conditions, which significantly influence the process of implementation of genetic information during the individual existence of an individual. At the early stages of individual development, intensive growth occurs (increase in mass and size), caused by the reproduction of molecules, cells and other structures, and differentiation, i.e. the emergence of differences in structure and complication of functions. At all stages of ontogenesis, various environmental factors (temperature, gravity, pressure, food composition in terms of the content of chemical elements and vitamins, various physical and chemical agents) have a significant regulatory influence on the development of the body. Studying the role of these factors in the process of individual development of animals and humans is of great practical importance, increasing as the anthropogenic impact on nature intensifies. In various fields of biology, medicine, veterinary medicine and other sciences, research is widely carried out to study the processes of normal and pathological development of organisms and to clarify the patterns of ontogenesis.

Irritability

An integral property of organisms and all living systems is irritability - the ability to perceive external or internal stimuli (impacts) and respond adequately to them. In organisms, irritability is accompanied by a complex of changes, expressed in shifts in metabolism, electrical potential on cell membranes, physicochemical parameters in the cytoplasm of cells, in motor reactions, and highly organized animals are characterized by changes in their behavior.

4. Central Dogma of Molecular Biology- a generalizing rule for the implementation of genetic information observed in nature: information is transmitted from nucleic acids To squirrel, but not in the opposite direction. The rule was formulated Francis Crick V 1958 year and brought into line with the data accumulated by that time in 1970 year. Transfer of genetic information from DNA To RNA and from RNA to squirrel is universal for all cellular organisms without exception; it underlies the biosynthesis of macromolecules. Genome replication corresponds to the information transition DNA → DNA. In nature, there are also transitions RNA → RNA and RNA → DNA (for example, in some viruses), as well as changes conformation proteins transferred from molecule to molecule.

Universal methods of transmitting biological information

In living organisms there are three types of heterogeneous, that is, consisting of different polymer monomers - DNA, RNA and protein. Information can be transferred between them in 3 x 3 = 9 ways. The Central Dogma divides these 9 types of information transfer into three groups:

General - found in most living organisms;

Special - found as an exception, in viruses and at mobile genome elements or under biological conditions experiment;

Unknown - not found.

DNA replication (DNA → DNA)

DNA is the main way of transmitting information between generations of living organisms, so accurate duplication (replication) of DNA is very important. Replication is carried out by a complex of proteins that unwind chromatin, then a double helix. After this, DNA polymerase and its associated proteins build an identical copy on each of the two chains.

Transcription (DNA → RNA)

Transcription is a biological process as a result of which the information contained in a section of DNA is copied onto the synthesized molecule messenger RNA. Transcription is carried out transcription factors And RNA polymerase. IN eukaryotic cell the primary transcript (pre-mRNA) is often edited. This process is called splicing.

Translation (RNA → protein)

Mature mRNA is read ribosomes during the broadcast process. IN prokaryotic In cells, the processes of transcription and translation are not spatially separated, and these processes are coupled. IN eukaryotic cell site of transcription cell nucleus separated from the broadcast location ( cytoplasm) nuclear membrane, so mRNA transported from the nucleus into the cytoplasm. mRNA is read by the ribosome in the form of three nucleotide"words". Complexes initiation factors And elongation factors deliver aminoacylated transfer RNAs to the mRNA-ribosome complex.

5. Reverse transcription is the process of forming a double-stranded DNA on a single-stranded matrix RNA. This process is called reverse transcription, since the transfer of genetic information occurs in the “reverse” direction relative to transcription.

The idea of ​​reverse transcription was very unpopular at first because it contradicted central dogma of molecular biology, which suggested that DNA transcribed to RNA and beyond broadcast into proteins. Found in retroviruses, For example, HIV and in case retrotransposons.

Transduction(from lat. transductio- movement) - transfer process bacterial DNA from one cell to another bacteriophage. General transduction is used in bacterial genetics to genome mapping and design strains. Both temperate phages and virulent ones are capable of transduction; the latter, however, destroy the bacterial population, so transduction with their help is not of great importance either in nature or in research.

A vector DNA molecule is a DNA molecule that acts as a carrier. The carrier molecule must have a number of features:

The ability to autonomously replicate in a host cell (usually bacterial or yeast)

Presence of a selective marker

Availability of convenient restriction sites

Bacterial plasmids most often act as vectors.

Detailed solution paragraph Summarize chapter 1 of biology for 11th grade students, authors I.N. Ponomareva, O.K. Kornilova, T.E. Loshchilina, P.V. Izhevsk Basic level 2012

• GD in Biology for grade 11 can be found
• Gdz workbook on Biology for grade 11 can be found

Test yourself

Define the biosystem “organism”.

An organism is a separate entity of living matter as an integral living system.

Explain whether the concepts “organism” and “individual” are different.

By organism (a physiological concept) we mean a living system as a whole, consisting of parts, as the interaction of cells, organs and other components of the body.

An individual (an ecological (population) concept) is a part of the environment (pack, pride, society), and not as a whole. An individual interacts with the surrounding world, and an organism is a world in which its parts interact.

Name the main properties of the biosystem “organism”.

Growth and development;

Nutrition and breathing;

Metabolism;

Openness;

Irritability;

Discreteness;

Self-reproduction;

Heredity;

Variability;

Unity chem. composition.

Explain what role the organism plays in the evolution of living nature.

Each organism (individual) carries within itself a piece of the gene pool (its own genotype) of the population. With each new crossing, the daughter individual receives a completely new genotype. This is a uniquely important role of organisms that carry out the process of constant renewal of hereditary properties in new generations thanks to sexual reproduction. One individual cannot evolve; it gives a “impetus” to an entire population, often a species. It can change, adapting to environmental conditions, but these are non-heritable traits. Organisms, like no other form of living matter, are able to sense the external world, the state of their body and respond to these sensations, purposefully changing their actions in response to irritation coming from external and internal factors. Organisms can learn and communicate with individuals of their own species, build homes and create conditions for raising young, and show parental care for their offspring.

5. Name the main mechanisms for controlling processes in the biosystem “organism”.

Humoral regulation, nervous regulation, hereditary information.

Describe the basic patterns of transmission of heredity in organisms.

Currently, many patterns of inheritance of properties (characters) of organisms have been established. All of them are reflected in the chromosomal theory of inheritance of characteristics of an organism. Let us name the main provisions of this theory.

Genes, being carriers of the hereditary properties of organisms, act as units of hereditary information.

The cytological basis of genes are groups of adjacent nucleotides in DNA chains.

Genes located on the chromosomes of the nucleus and cell are inherited as separate independent units.

In all organisms of the same species, each gene is always located in the same place (locus) on a particular chromosome.

Any changes in a gene lead to the appearance of its new varieties - alleles of this gene and, consequently, to a change in the trait.

All the chromosomes and genes of an individual are always present in its cells in the form of a pair that gets into the zygote from both parents during fertilization.

Each gamete can have only one identical (homologous) chromosome and one gene from an allelic pair.

During meiosis, different pairs of chromosomes are distributed between gametes independently of each other, and the genes located on these chromosomes are also inherited completely randomly.

An important source of the emergence of new gene combinations is crossing over.

The development of organisms occurs under the control of genes in close connection with environmental factors.

The revealed patterns of inheritance of properties are observed in all living organisms with sexual reproduction without exception.

Formulate Mendel's first and second laws.

Mendel's first law (law of uniformity of first generation hybrids). When crossing two homozygous organisms belonging to different pure lines and differing from each other in one pair of alternative manifestations of the trait, the entire first generation of hybrids (F1) will be uniform and will carry the manifestation of the trait of one of the parents.

Mendel's second law (law of segregation). When two heterozygous descendants of the first generation are crossed with each other, in the second generation a split is observed in a certain numerical ratio: by phenotype 3:1, by genotype 1:2:1.

Why is Mendel's third law not always observed in the inheritance of traits?

The law of independent inheritance for each pair of traits once again emphasizes the discrete nature of any gene. Discreteness is manifested both in the independent combination of alleles of different genes, and in their independent action - in phenotypic expression. The independent distribution of genes can be explained by the behavior of chromosomes during meiosis: pairs of homologous chromosomes, and with them paired genes, are redistributed and dispersed into gametes independently of each other.

How are dominant and recessive alleles of a gene inherited?

the functional activity of the dominant allele of a gene does not depend on the presence of another gene for this trait in the body. The dominant gene is thus dominant; it manifests itself already in the first generation.

The recessive allele of a gene can appear in the second and subsequent generations. For a trait formed by a recessive gene to manifest, it is necessary that the offspring receive the same recessive variant of this gene from both the father and the mother (i.e. in the case of homozygosity). Then, in the corresponding pair of chromosomes, both sister chromosomes will have only this one variant, which will not be suppressed by the dominant gene and will be able to manifest itself in the phenotype.

10. Name the main types of gene linkage.

A distinction is made between incomplete and complete gene linkage. Incomplete linkage is the result of crossing over between linked genes, while complete linkage is possible only in cases where crossing over does not occur.

How does sex develop in animals and humans?

After fertilization, i.e., when the male and female chromosomes merge, a certain combination of either XX or XY can appear in the zygote.

In mammals, including humans, a female organism (XX) develops from a zygote homogametic on the X chromosome, and a male organism (XY) develops from a heterogametic zygote. Later, when the organism that has already developed from the zygote is able to form its gametes, then in the female body (XX) eggs with only X chromosomes will appear, while in the male body two types of sperm will be formed: 50% with the X chromosome and the same number of others - with the Y chromosome.

What is ontogeny?

Ontogenesis is the individual development of an organism, the development of an individual from zygote to death.

Explain what a zygote is; reveal its role in evolution.

A zygote is a cell formed by the fusion of two gametes (sex cells) - a female (egg) and a male (sperm) as a result of the sexual process. They contain a double (diploid) set of homologous (paired) chromosomes. From the zygote, the embryos of all living organisms that have a diploid set of homologous chromosomes are formed - plants, animals and humans.

Describe the features of the stages of ontogenesis in multicellular organisms.

In ontogenesis, two periods are usually distinguished - embryonic and postembryonic - and the stages of the adult organism.

The embryonic (embryo) period of development of a multicellular organism, or embryogenesis, in animals covers the processes occurring from the first division of the zygote to the exit from the egg or the birth of a young individual, and in plants - from the division of the zygote to the germination of the seed and the appearance of the seedling.

The embryonic period in most multicellular animals includes three main stages: cleavage, gastrulation and differentiation, or morphogenesis.

As a result of a series of successive mitotic divisions of the zygote, numerous (128 or more) small cells are formed - blastomeres. During division, the resulting daughter cells do not diverge and do not increase in size. With each subsequent step, they become smaller and smaller, since there is no increase in the volume of the cytoplasm in them. Therefore, the process of cell division without increasing the volume of the cytoplasm is called fragmentation. Over time, the embryo takes the form of a vesicle with a wall formed by a single layer of cells. Such a single-layer embryo is called a blastula, and the cavity formed inside is called a blastocoel. During further development, the blastocoel turns into the primary body cavity in a number of invertebrates, and in vertebrates it is almost completely replaced by the secondary body cavity. After the formation of a multicellular blastula, the process of gastrulation begins: the movement of some cells from the surface of the blastula inward, to the sites of future organs. As a result, a gastrula is formed. It consists of two layers of cells - germ layers: the outer - ectoderm and the inner - endoderm. In most multicellular animals, during the process of gastrulation, a third germ layer, the mesoderm, is formed. It is located between the ectoderm and endoderm.

During the process of gastrulation, cells differentiate, that is, they become different in structure and biochemical composition. Biochemical specialization of cells is ensured by different (differentiated) gene activity. The differentiation of the cells of each germ layer leads to the formation of various tissues and organs, i.e., morphogenesis, or morphogenesis, occurs.

A comparison of the embryogenesis of various vertebrates, such as fish, amphibians, birds and mammals, shows that their early stages of development are very similar to each other. But at later stages, the embryos of these animals differ quite greatly.

The postembryonic, or postembryonic, period begins from the moment the organism emerges from the egg membranes or from the moment of birth and continues until maturity. During this period, the processes of morphogenesis and growth are completed, which is determined primarily by the genotype, as well as the interaction of genes with each other and with environmental factors. In humans, the duration of this period is 13-16 years.

In many animals, there are two types of postembryonic development - direct and indirect.

During ontogenesis, growth, differentiation and integration of parts of a developing multicellular organism occur. According to modern concepts, the zygote contains a program in the form of a code of hereditary information that determines the course of development of a given organism (individual). This program is realized in the processes of interaction between the nucleus and the cytoplasm in each cell of the embryo, between its different cells and between complexes of cells in the germ layers.

Stages of an adult organism. An adult is an organism that has reached sexual maturity and is capable of reproduction. In an adult organism, there are distinguished: the generative stage and the stage of aging.

The generative stage of an adult organism ensures the appearance of offspring through reproduction. Thus, the continuity of existence of populations and species is realized. For many organisms, this period lasts a long time - many years, even for those who give birth only once in their lives (salmon fish, river eels, mayflies, and in plants - many types of bamboo, umbelliferae and agave). However, there are many species in which adult organisms repeatedly produce offspring over a number of years.

At the aging stage, various changes in the body are observed, leading to a decrease in its adaptive capabilities and an increase in the likelihood of death.

15. Describe the main types of nutrition of organisms.

There are two types of nutrition of living organisms: autotrophic and heterotrophic.

Autotrophs (autotrophic organisms) are organisms that use carbon dioxide as a carbon source (plants and some bacteria). In other words, these are organisms capable of creating organic substances from inorganic ones - carbon dioxide, water, mineral salts.

Heterotrophs (heterotrophic organisms) are organisms that use organic compounds (animals, fungi and most bacteria) as a carbon source. In other words, these are organisms that are not capable of creating organic substances from inorganic ones, but require ready-made organic substances. According to the state of the food source, heterotrophs are divided into biotrophs and saprotrophs.

Some living beings, depending on living conditions, are capable of both autotrophic and heterotrophic nutrition (mixotrophs).

16. Describe the most important factors that shape health.

Genotype as a health factor. The basis of human health is the body’s ability to withstand environmental influences and maintain relative constancy of homeostasis. Violation of homeostasis for various reasons causes illness and health problems. However, the type of homeostasis itself, the mechanisms of its maintenance at all stages of ontogenesis in certain conditions are determined by genes, or more precisely, by the genotype of the individual.

Habitat as a factor of health. It has long been noted that both heredity and environment play a role in the formation of any trait. Moreover, sometimes it is difficult to determine on what one or another sign depends more. For example, a trait such as height is inherited through many genes (polygenic), i.e., achieving the normal growth characteristic of parents depends on a number of genes that control the level of hormones, calcium metabolism, the complete supply of digestive enzymes, etc. At the same time, even the “best” genotype in terms of growth under poor living conditions (lack of nutrition, sun, air, movement) inevitably leads to a lag in body length.

Social factors of health. Unlike plants and animals, in humans a special area of ​​ontogenesis is the formation of his intellect, moral character, and individuality. Here, along with biological and non-biological factors common to all living things, a new powerful environmental factor operates - social. If the former mainly determine the potential range of reaction norms, then the social environment, upbringing and lifestyle determine the specific embodiment of hereditary inclinations in a given individual. The social environment acts as a unique mechanism for transmitting the historical experience of mankind, its cultural, scientific and technical achievements.

17. Explain the role of single-celled organisms in nature.

In unicellular organisms, metabolic processes occur relatively quickly, so they make a large contribution to the circulation of substances in the biogeocenosis, especially to the carbon cycle. In addition, single-celled animals (protozoa), by ingesting and digesting bacteria (i.e., primary decomposers), accelerate the process of updating the composition of the bacterial population. Herbivorous and predatory organisms also perform their function in the ecosystem, directly participating in the breakdown of plant and animal material.

18. Describe the role of mutagens in nature and in human life.

Mutagens are of physical and chemical nature. Mutagens include toxic substances (for example, colchicine), X-ray, radioactive, carcinogenic and other adverse environmental influences. Mutations occur under the influence of mutagens. Mutagens cause disruption of the normal processes of replication, recombination or divergence of genetic information carriers.

When ionizing radiation (electromagnetic X-rays and gamma rays, as well as elementary particles (alpha, beta, neutrons, etc.) interact with the body, cell components, including DNA molecules, absorb a certain amount (dose) of energy.

Many chemical compounds have been identified that have mutagenic activity: the fibrous mineral asbestos, ethyleneamine, colchicine, benzopyrene, nitrites, aldehydes, pesticides, etc. Often these substances are also carcinogens, that is, they can cause the development of malignant neoplasms (tumors) in the body. . Some living organisms, such as viruses, have also been identified as mutagens.

It is known that polyploid forms are often found among plant organisms in high mountain or arctic conditions - a consequence of spontaneous genome mutations. This is due to sudden temperature changes during the growing season.

When contacting mutagens, one must remember that they have a strong effect on the development of germ cells, on the hereditary information contained in them, and on the processes of embryo development in the mother’s uterus.

19. Describe the significance of modern advances in genetics for human health.

It is thanks to genetics that therapy methods are now being developed that make it possible to treat previously incurable diseases. Thanks to modern advances in genetics, there are now DNA and RNA tests, thanks to which it is possible to detect cancer in the early stages. We also learned how to obtain enzymes, antibiotics, hormones, and amino acids. For example, for those who suffer from diabetes mellitus, insulin was obtained by genetic means.

On the one hand, modern advances in genetics provide new possibilities for diagnosing and treating humans. On the other hand, advances in genetics have a negative impact on human health through food consumption, expressed in the widespread distribution of genetically modified food products. Eating such foods may weaken the immune system, worsen the general condition, resistance to antibiotics, and may cause cancer, primarily affecting the gastrointestinal tract (GIT).

20. Explain whether a virus can be called an organism, an individual.

When a virus reproduces its own kind in a host cell, it is an organism, and a very active one. Outside the host cell, the virus has no signs of a living organism.

The extremely primitive structure of the virus, the simplicity of its organization, the absence of cytoplasm and ribosomes, as well as its own metabolism, small molecular weight - all this, distinguishing viruses from cellular organisms, gives rise to a discussion of the question: what is a virus - a creature or substance, living or non-living? ? Scientific debate on this topic continued for a long time. However, now, thanks to a thorough study of the properties of a huge number of types of viruses, it has been established that a virus is a special form of life of an organism, albeit a very primitive one. The structure of the virus, represented by its main parts interacting with each other (nucleic acid and proteins), the definite structure (core and protein shell - capsid), its maintenance of its structure, allow us to consider the virus as a special living system - an organism-level biosystem, albeit a very primitive one.

21. Choose the correct answer from those proposed (the correct one is underlined).

1. Genes that control the development of opposite traits are called:

a) allelic (correct); b) heterozygous; c) homozygous; d) linked.

2. “Splitting for each pair of characteristics occurs independently of other pairs of characteristics,” - this is how it is formulated:

a) Mendel's first law; b) Mendel's second law; c) Mendel's third law (correct); d) Morgan's law.

3. In tropical regions of the Earth, white cabbage does not form heads. What form of variability is manifested in this case?

a) mutational; b) combinative; c) modification (correct); d) ontogenetic.

4. A randomly appeared lamb with shortened legs (an advantageous deformity for humans - it does not jump over a fence) gave rise to the Onkon sheep breed. What type of variability are we talking about here?

a) mutational (correct); b) combinative; c) modification; d) ontogenetic.

Express your point of view.

As you know, the basic unit of evolution is the population. What is the role of organisms in the microevolutionary process?

At the organismal level, the process of fertilization and individual development of an individual first appears as a process of implementation of hereditary information contained in chromosomes and their genes, as well as an assessment by natural selection of the viability of this individual.

Organisms are exponents of the hereditary properties of populations and species. It is organisms that determine the success or failure of a population in the struggle for environmental resources and in the struggle for existence between individuals. Therefore, in all micropopulation processes of historical significance, organisms are direct participants. New properties of the species accumulate in organisms. Selection exerts its effect on organisms, leaving the more adapted and discarding others.

At the organismal level, the bidirectionality of life of each organism is manifested. On the one hand, this is the ability of an organism (individual), focused on survival and reproduction. On the other hand, it is ensuring the longest possible existence of its population and species, sometimes to the detriment of the life of the organism itself. This reveals the important, evolutionary significance of the organismal level in nature.

Symbiotic methods of feeding organisms arose during their evolution. How do newborns master this method?

They do not need to learn a symbiotic lifestyle or way of eating. In the process of evolution, they also developed all the necessary adaptations for recognizing the required individual or substrate. For example, special receptors for the perception of another symbiotic individual or morphological structures that facilitate the feeding process itself. Moreover, most symbiotic individuals are born near the parent organism and immediately find themselves in favorable conditions for development.

Symbiotic behavior is passed on from parents. For example, in birds or in mammals in relation to bacteria.

Why is it believed that a person’s way of life is an indicator of his culture?

From how a person protects himself, takes care of himself, etc., one can judge the level of his upbringing; this is directly related to the development of a person, his spiritual values ​​and culture itself, behavior, and lifestyle in general.

At the beginning of the 20th century. The aphorism that writer Maxim Gorky put into the mouth of his hero Satin in the play “At the Lower Depths” became famous: “Man - that sounds proud!” Can you currently support or refute this statement?

Currently, this is a philosophical question... Science has created a huge number of complex technical means, is trying to penetrate into space and cells, to find out the secrets of the living world, the causes of diseases, and the possibility of extending human life. At the same time, “perfect” means of destroying all life on Earth were developed. Is this the pride of humanity?

For a person, there are a lot of common nouns that reflect his inner essence: slave, fool, robber, beast, dog, beast; at the same time: genius, creator, creator, intelligent, clever! So what is the difference between a genius and a fool? What qualities, by what criteria should they be assessed and compared?

Each person has his own purpose on Earth. His well-being, self-confidence, and pride in himself depend on whether he understands it.

Man, as a biological being, is definitely the pride of the Earth. We know how to think, express our emotions, and speak.

But if a person understands within himself that he must not harm anyone or anything, live in harmony with himself, with others and nature, value life and not only his own, then such a person is truly proud!!!

Problem to discuss

In 1992, at the UN Conference on the Environment in Rio de Janeiro, at the level of leaders of 179 states, including Russia, the most important documents were adopted to prevent the degrading development of the biosphere. One of the programs of action for humanity in the 21st century. - “Preservation of biological diversity” has the motto: “Biological resources feed and clothe us, provide housing, medicine and spiritual food.”

Express your opinion on this motto. Can you clarify it, expand it? Why is biological diversity a major human value?

This motto once again reminds us that we (people) on Earth must live in harmony with nature (take something and give something in return), and not mercilessly use it for our own purposes.

Morality, nature, man are identical concepts. And unfortunately, in our society it is precisely the interconnection of these concepts that is destroyed. Parents teach their children decency, kindness, love for the world around them, spirituality and care, but in reality we don’t give this to them. We have lost and squandered the wealth that had been stored and accumulated for centuries. They overthrew and consigned to oblivion the covenants, traditions, and experience of past generations in relation to the world around them. They practically destroyed it with their own hands, with their callousness, thoughtlessness, and mismanagement.

Radiation and acid rain, crops covered in toxic chemicals, shallow rivers, silted lakes and ponds turned into swamps, deforested forests, destroyed animals, modified organisms and products - this is our modern legacy. And now, suddenly, the whole world realizes that we are on the verge of destruction and everyone, precisely everyone, in their place, must, bit by bit, persistently and conscientiously restore, heal, grow good. Without biodiversity WE ARE NOTHING. Biological diversity is the main universal human value.

Basic Concepts

An organism is a separateness of living matter as an individual (individual) and as an integral living system (biosystem).

Heredity is the ability of an organism to transmit features of structure, functioning and development from parents to offspring. Heredity is determined by genes.

Variability is the property of living organisms to exist in various forms, providing them with the ability to survive in changing conditions.

Chromosomes are structures of the cell nucleus that are carriers of genes and determine the hereditary properties of cells and organisms. Chromosomes are made up of DNA and proteins.

A gene is an elementary unit of heredity, represented by a biopolymer - a segment of a DNA molecule that contains information about the primary structure of one protein or rRNA and tRNA molecules.

Genome – a set of genes of a species that includes an organism (individual). The genome is also called the set of genes characteristic of the haploid (1n) set of chromosomes of a given type of organism, or the main haploid set of chromosomes. At the same time, the genome is considered both as a functional unit and as a characteristic of a species necessary for the normal development of organisms of a given species.

Genotype is a system of interacting genes of an organism (individual). The genotype expresses the totality of genetic information of an individual (organism).

Reproduction is the reproduction of one's own kind. This property is characteristic only of living organisms.

Fertilization is the union of the nuclei of male and female germ cells - gametes, leading to the formation of a zygote and the subsequent development of a new (daughter) organism from it.

A zygote is a single cell that is formed by the fusion of female and male reproductive cells (gametes).

Ontogenesis is the individual development of an organism, including the entire complex of consistent and irreversible changes, starting from the formation of a zygote to the natural death of the organism.

Homeostasis is a state of relative dynamic equilibrium of a system (including biological), maintained through self-regulation mechanisms.

Health is the state of any living organism in which it as a whole and all its organs are able to fully perform their functions. There is no illness or disease.

The virus is a unique precellular life form with a heterotrophic type of nutrition. A DNA or RNA molecule is replicated within the affected cell.

The organismal level of organization of living matter reflects the characteristics of individual individuals and their behavior. The structural and functional unit of the organismal level is the organism. The following phenomena occur at the organismal level: reproduction, functioning of the organism as a whole, ontogenesis, etc.

The following levels of life organization are distinguished: molecular, cellular, organ-tissue (sometimes they are separated), organismal, population-species, biogeocenotic, biosphere. Living nature is a system, and the various levels of its organization form its complex hierarchical structure, when the underlying simpler levels determine the properties of the higher ones.

So complex organic molecules are part of cells and determine their structure and vital functions. In multicellular organisms, cells are organized into tissues, and several tissues form an organ. A multicellular organism consists of organ systems; on the other hand, the organism itself is an elementary unit of a population and a biological species. A community is represented by interacting populations of different species. The community and environment form a biogeocenosis (ecosystem). The totality of planet Earth's ecosystems forms its biosphere.

At each level, new properties of living things arise that are absent at the underlying level, and their own elementary phenomena and elementary units are distinguished. At the same time, in many ways the levels reflect the course of the evolutionary process.

The identification of levels is convenient for studying life as a complex natural phenomenon.

Let's take a closer look at each level of life organization.

Molecular level

Although molecules are made up of atoms, the difference between living and nonliving matter begins to appear only at the molecular level. Only living organisms contain a large number of complex organic substances - biopolymers (proteins, fats, carbohydrates, nucleic acids). However, the molecular level of organization of living things also includes inorganic molecules that enter cells and play an important role in their life.

The functioning of biological molecules underlies a living system. At the molecular level of life, metabolism and energy conversion are manifested as chemical reactions, transmission and change of hereditary information (reduplication and mutations), as well as a number of other cellular processes. Sometimes the molecular level is called molecular genetic.

Cellular level of life

It is the cell that is the structural and functional unit of living things. There is no life outside the cell. Even viruses can exhibit the properties of a living thing only when they are in the host cell. Biopolymers fully demonstrate their reactivity when organized into a cell, which can be considered as a complex system of molecules interconnected primarily by various chemical reactions.

At this cellular level, the phenomenon of life manifests itself, the mechanisms of transmission of genetic information and the transformation of substances and energy are coupled.

Organ-tissue

Only multicellular organisms have tissues. Tissue is a collection of cells similar in structure and function.

Tissues are formed in the process of ontogenesis by differentiation of cells having the same genetic information. At this level, cell specialization occurs.

Plants and animals have different types of tissues. So in plants it is a meristem, protective, basic and conductive tissue. In animals - epithelial, connective, muscular and nervous. Tissues may include a list of subtissues.

An organ usually consists of several tissues interconnected into a structural and functional unity.

Organs form organ systems, each of which is responsible for an important function for the body.

The organ level in unicellular organisms is represented by various cell organelles that perform the functions of digestion, excretion, respiration, etc.

Organismic level of organization of living things

Along with the cellular level, separate structural units are distinguished at the organismal (or ontogenetic) level. Tissues and organs cannot live independently, organisms and cells (if it is a single-celled organism) can.

Multicellular organisms are made up of organ systems.

At the organismal level, such life phenomena as reproduction, ontogenesis, metabolism, irritability, neurohumoral regulation, and homeostasis are manifested. In other words, its elementary phenomena constitute the natural changes of the organism in individual development. The elementary unit is the individual.

Population-species

Organisms of the same species, united by a common habitat, form a population. A species usually consists of many populations.

Populations have a common gene pool. Within a species, they can exchange genes, i.e. they are genetically open systems.

Elementary evolutionary phenomena occur in populations, ultimately leading to speciation. Living nature can evolve only at supraorganism levels.

At this level, the potential immortality of the living arises.

Biogeocenotic level

Biogeocenosis is an interacting set of organisms of different species with various environmental factors. Elementary phenomena are represented by matter-energy cycles, provided primarily by living organisms.

The role of the biogeocenotic level is the formation of stable communities of organisms of different species, adapted to living together in a certain habitat.

Biosphere

The biosphere level of life organization is a system of the highest order of life on Earth. The biosphere covers all manifestations of life on the planet. At this level, there is a global circulation of substances and a flow of energy (encompassing all biogeocenoses).

All living organisms in nature consist of the same levels of organization; this is a characteristic biological pattern common to all living organisms.
The following levels of organization of living organisms are distinguished: molecular, cellular, tissue, organ, organismal, population-species, biogeocenotic, biosphere.

Rice. 1. Molecular genetic level

1. Molecular genetic level. This is the most elementary level characteristic of life (Fig. 1). No matter how complex or simple the structure of any living organism, they all consist of the same molecular compounds. An example of this are nucleic acids, proteins, carbohydrates and other complex molecular complexes of organic and inorganic substances. They are sometimes called biological macromolecular substances. At the molecular level, various life processes of living organisms occur: metabolism, energy conversion. With the help of the molecular level, the transfer of hereditary information is carried out, individual organelles are formed and other processes occur.

Rice. 2. Cellular level

2. Cellular level. The cell is the structural and functional unit of all living organisms on Earth (Fig. 2). Individual organelles within a cell have a characteristic structure and perform a specific function. The functions of individual organelles in a cell are interconnected and perform common vital processes. In single-celled organisms (unicellular algae and protozoa), all life processes take place in one cell, and one cell exists as a separate organism. Remember unicellular algae, chlamydomonas, chlorella and the simplest animals - amoeba, ciliates, etc. In multicellular organisms, one cell cannot exist as a separate organism, but it is an elementary structural unit of the organism.

Rice. 3. Tissue level

3. Tissue level. A collection of cells and intercellular substances similar in origin, structure and function forms tissue. The tissue level is characteristic only of multicellular organisms. Also, individual tissues are not an independent integral organism (Fig. 3). For example, the bodies of animals and humans consist of four different tissues (epithelial, connective, muscle, nervous). Plant tissues are called: educational, integumentary, supporting, conductive and excretory. Remember the structure and functions of individual tissues.

Rice. 4. Organ level

4. Organ level. In multicellular organisms, the union of several identical tissues, similar in structure, origin and function, forms the organ level (Fig. 4). Each organ contains several tissues, but among them one is the most significant. A separate organ cannot exist as a whole organism. Several organs, similar in structure and function, combine to form an organ system, for example, digestion, respiration, blood circulation, etc.

Rice. 5. Organismal level

5. Organismal level. Plants (Chlamydomonas, Chlorella) and animals (amoeba, ciliates, etc.), whose bodies consist of one cell, are an independent organism (Fig. 5). And an individual individual of multicellular organisms is considered as a separate organism. In each individual organism, all life processes characteristic of all living organisms occur - nutrition, respiration, metabolism, irritability, reproduction, etc. Each independent organism leaves behind offspring. In multicellular organisms, cells, tissues, organs, and organ systems are not a separate organism. Only an integral system of organs that specifically perform various functions forms a separate independent organism. The development of an organism, from fertilization to the end of life, takes a certain period of time. This individual development of each organism is called ontogenesis. An organism can exist in close relationship with its environment.

Rice. 6. Population-species level

6. Population-species level. A collection of individuals of one species or group that exists for a long time in a certain part of the range, relatively separately from other populations of the same species, constitutes a population. At the population level, the simplest evolutionary transformations are carried out, which contributes to the gradual emergence of a new species (Fig. 6).

Rice. 7 Biogeocenotic level

7. Biogeocenotic level. A collection of organisms of different species and varying complexity of organization, adapted to the same conditions of the natural environment, is called a biogeocenosis, or natural community. The biogeocenosis includes numerous species of living organisms and natural environmental conditions. In natural biogeocenoses, energy accumulates and is transferred from one organism to another. Biogeocenosis includes inorganic, organic compounds and living organisms (Fig. 7).

Rice. 8. Biosphere level

8. Biosphere level. The totality of all living organisms on our planet and their common natural habitat constitutes the biosphere level (Fig. 8). At the biosphere level, modern biology solves global problems, for example, determining the intensity of the formation of free oxygen by the Earth's vegetation or changes in the concentration of carbon dioxide in the atmosphere associated with human activity. The main role at the biosphere level is played by “living substances,” that is, the totality of living organisms inhabiting the Earth. Also at the biosphere level, “bio-inert substances” are important, formed as a result of the vital activity of living organisms and “inert” substances (i.e., environmental conditions). At the biosphere level, the circulation of matter and energy occurs on Earth with the participation of all living organisms of the biosphere.

Levels of life organization. Population. Biogeocenosis. Biosphere.

1. Currently, there are several levels of organization of living organisms: molecular, cellular, tissue, organ, organismal, population-species, biogeocenotic and biosphere.
2. At the population-species level, elementary evolutionary transformations are carried out.
3. The cell is the most basic structural and functional unit of all living organisms.
4. A collection of cells and intercellular substances similar in origin, structure and function forms tissue.
5. The totality of all living organisms on the planet and their general natural habitat constitutes the biosphere level.
1. Name the levels of life organization in order.
2. What is fabric?
3. What are the main parts of a cell?
1. What organisms are characterized by the tissue level?
2. Describe the organ level.
3. What is a population?
1. Describe the organismal level.
2. Name the features of the biogeocenotic level.
3. Give examples of the interconnectedness of the levels of organization of life.

Fill out the table showing the structural features of each level of the organization:

Serial number	Levels of organization	Peculiarities

Updating knowledge What is life? What levels of life organization do you know? What levels of life organization have you already studied? Name the elementary unit and structural elements of the organismal level? How are living organisms classified? What basic processes occur at the organismal level? Name the significance and role of the organismal level in nature.

Life is a higher form of existence of matter compared to the physical and chemical, which naturally arises under certain conditions in the process of its development. Living objects differ from non-living ones in their metabolism, an indispensable condition of life, the ability to reproduce, grow, actively regulate their composition and functions, to various forms of movement, irritability, adaptability to the environment, etc.

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