In nature, it is expressed primarily in the fact that at this level the main discrete living unit arose - an organism characterized by self-maintenance of its structure, self-renewal, actively responding to external influences and able to interact with other organisms.
It was at the organismic level that the processes expressing the essence of life appeared for the first time in living matter:
- search for shelters and ways of obtaining food;
- gas exchange as a process of respiration;
- management of physiological processes with the help of the humoral and nervous systems;
- communication between members of their own species and other species.
At the organismic level, for the first time, the process of fertilization and individual development of an individual appears as a process of implementing hereditary information contained in chromosomes and their genes, as well as assessing the viability of this individual by natural selection.
Organisms are expressions 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. Organisms accumulate new properties of the species. Selection exerts its effect on organisms, leaving the fittest and discarding others.
At the organismic level, the bidirectionality of the life of each organism is manifested. On the one hand, it is the possibility of an organism (individual) oriented towards survival and reproduction. On the other hand, this is to ensure 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 organism level in nature.
It should also be noted that organisms, participating in food chains to maintain their life processes (in order to survive), are actively involved as the main carriers of substances and energy in the biological cycle and energy transformation in biogeocenoses. This expresses global role organisms (autogrophs and heterotrophs) and, in general, the organismic standard of living in structure and stability
Detailed solution paragraph Summarize chapter 1 in biology for grade 11 students, authors I.N. Ponomareva, O.K. Kornilova, T.E. Loshchilin, P.V. Izhevsk A basic level of 2012
- Gdz in Biology for grade 11 can be found
- Gdz workbook in Biology for grade 11 can be found
Test yourself
Define the biosystem "organism".
The organism is a separate living matter as an integral living system.
Explain the difference between the concepts "organism" and "individual".
Under the organism (the concept of physiological) is meant a living system as a whole, consisting of parts, as an interaction of cells, organs and other components of the body.
An individual (an ecological (population) concept) is a part of the environment (flocks, pride, society), and not as a whole. An individual interacts with the outside 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 respiration;
Metabolism;
openness;
Irritability;
discreteness;
Self-reproduction;
Heredity;
Variability;
The unity of chem. composition.
Explain what role the organism plays in the evolution of living nature.
Each organism (individual) carries a part of the gene pool (its own genotype) of the population. With each new crossing, the daughter individual receives a completely new genotype. This is the role of organisms, unique in its significance, carrying out the process of constant renewal of hereditary properties in new generations, thanks to sexual reproduction. One individual cannot evolve, it gives a "push" to the whole population, often to a species. It can change, adapting to environmental conditions, but these are non-inherited 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 by 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 dwellings and create conditions for breeding cubs, and show parental care for offspring.
5. What are the main mechanisms for managing processes in the biosystem "organism".
Humoral regulation, nervous regulation, hereditary information.
Describe the main patterns of heredity transmission in organisms.
At present, many laws of inheritance of properties (features) of organisms have been established. All of them are reflected in the chromosomal theory of inheritance of organism traits. 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 the 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 chromosomes and genes in an individual are always present in its cells in the form of a pair that fell 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 among the gametes independently of each other and, quite by chance, the genes located on these chromosomes are also inherited.
Crossing over is an important source of new gene combinations.
The development of organisms occurs under the control of genes in close relationship with environmental factors.
The revealed patterns of inheritance of properties are observed in all living organisms with sexual reproduction without exception.
State the first and second laws of Mendel.
Mendel's first law (the law of uniformity of hybrids of the first generation). 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 splitting). When two heterozygous descendants of the first generation are crossed with each other, in the second generation splitting 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 diverge into gametes independently of each other.
How are dominant and recessive alleles of a gene inherited?
the functional activity of the dominant allele of the gene does not depend on the presence in the body of another gene of this trait. The dominant gene is thus dominant, it appears already in the first generation.
The recessive allele of a gene may appear in the second and subsequent generations. For the manifestation of a trait formed by a recessive gene, it is necessary that the offspring receive the same recessive variant of this gene from both the father and the mother (ie, 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 can manifest itself in the phenotype.
10. Name the main types of gene linkage.
Distinguish between incomplete and complete linkage of genes. Incomplete linkage is the result of crossing over (crossover) between linked genes, while complete linkage is possible only in cases where crossing over does not occur.
How is the formation of sex in animals and humans?
After fertilization, that is, when the male and female chromosomes merge, a certain combination of either XX or XY may 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 will be able to form its gametes, then in the female body (XX) eggs will appear only with X chromosomes, while in the male body spermatozoa of two types will be formed: 50% with the X chromosome and the same number of others - with a Y-chromosome.
What is ontogeny?
Ontogenesis is the individual development of an organism, the development of an individual from a 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) - female (ovum) and male (sperm) as a result of the sexual process. Contain a double (diploid) set of homologous (paired) chromosomes. From the zygote, the embryos of all living organisms with 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 stages of an adult organism.
The embryonic (embryonic) 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 seed germination and the appearance of a 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. When dividing, 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 an increase in the volume of the cytoplasm is called crushing. Over time, the embryo takes the form of a bubble with a wall formed by one layer of cells. Such a single-layer embryo is called a blastula, and the cavity formed inside is called a blastocoel. In the course of 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 part of the cells from the surface of the blastula inward, to the places of future organs. As a result, a gastrula is formed. It consists of two layers of cells - germ layers: outer - ectoderm and inner - endoderm. In most multicellular animals, during gastrulation, a third germ layer, the mesoderm, is formed. It is located between the ectoderm and endoderm.
In the process of gastrulation, cells differentiate, that is, they become different in structure and biochemical composition. Biochemical specialization of cells is provided by different (differentiated) activity of genes. Differentiation of the cells of each germ layer leads to the formation of various tissues and organs, i.e., morphogenesis, or shaping, takes place.
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 on late stages the embryos of these animals differ already quite strongly.
The post-embryonic, or post-embryonic, period begins from the moment the organism leaves the egg membranes or from the moment of birth and continues until sexual maturity. During this period, the processes of shaping 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, two types of postembryonic development are distinguished - direct and indirect.
During ontogenesis, growth, differentiation and integration of parts of a developing multicellular organism occur. According to modern concepts, the zygote has 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 implemented in the processes of interaction between the nucleus and cytoplasm in each cell of the embryo, between its different cells, and between cell complexes in the germ layers.
Stages of an adult organism. An adult is an organism that has reached the state of puberty and is capable of reproduction. In an adult organism, a generative stage and an aging stage are distinguished.
The generative stage of an adult organism ensures the appearance of offspring through reproduction. Thus, the continuity of the 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 a lifetime (salmon fish, river eel, mayflies, and in plants - many types of bamboo, umbrella and agave). However, there are many species in which adult organisms repeatedly produce offspring over a number of years.
At the stage of aging, various changes in the body are observed, leading to a decrease in its adaptive capabilities, to an increase in the likelihood of death.
15. Describe the main types of nutrition of organisms.
There are two types of nutrition in living organisms: autotrophic and heterotrophic.
Autotrophs (autotrophic organisms) - organisms that use carbon dioxide as a source of carbon (plants and some bacteria). In other words, these are organisms capable of creating organic substances from inorganic - carbon dioxide, water, mineral salts.
Heterotrophs (heterotrophic organisms) - organisms that use organic compounds (animals, fungi and most bacteria) as a carbon source. In other words, these are organisms that are not able to create organic substances from inorganic ones, but need ready-made organic matter Oh. According to the state of the food source, heterotrophs are divided into biotrophs and saprotrophs.
Some living beings, depending on the habitat 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 ability of his body to withstand environmental influences and maintain a relative constancy of homeostasis. Violation of homeostasis for various reasons causes disease, health problems. However, the type of homeostasis itself, the mechanisms of its maintenance at all stages of ontogeny under certain conditions, are determined by genes, 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, it is sometimes difficult to determine what this or that sign depends more on. For example, such a trait as height is inherited with the help of many genes (polygenic), i.e., achieving normal growth characteristic of parents depends on a number of genes that control the level of hormone exposure, calcium metabolism, the usefulness of the intake 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. In contrast to plants and animals, a special area of ontogenesis in humans is the formation of his intellect, moral character, and personality. Here, along with biological and non-biological factors common to all living things, there is a new powerful factor of the environment - social. If the former basically determine the potential range of the reaction norm, then the social environment, upbringing and lifestyle determine the specific embodiment of hereditary inclinations in a given individual. The social environment acts as a kind of mechanism for transferring the historical experience of mankind, its cultural, scientific and technical achievements.
17. Explain what is the role of unicellular organisms in nature.
In unicellular metabolic processes proceed relatively quickly, therefore they make a great contribution to the cycle of substances in the biogeocenosis, especially to the carbon cycle. In addition, unicellular animals (protozoa) by swallowing and digesting bacteria (i.e., primary decomposers) accelerate the process of renewal of 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 poisonous substances (for example, colchicine), X-ray, radioactive, carcinogenic and other adverse environmental effects. Under the influence of mutagens, mutations occur. Mutagens cause disruption of the normal processes of replication, recombination or divergence of genetic information carriers.
During the interaction of ionizing radiation (electromagnetic X-rays and gamma rays, as well as elementary particles (alpha, beta, neutrons, etc.) 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, i.e., 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.
In contact with 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 development of the embryo in the mother's uterus.
19. Describe the importance of modern achievements in genetics for human health.
It is thanks to genetics that such methods of therapy are now being developed, thanks to which it is possible to treat diseases that were previously incurable. Thanks to modern advances in genetics, there are now DNA and RNA tests, thanks to which it is possible to detect cancer at an early stage. They also learned how to get enzymes, antibiotics, hormones, amino acids. For example, for those who suffer from diabetes, insulin has been genetically obtained.
On the one hand, modern achievements in genetics provide new opportunities for diagnosing and treating a person. On the other hand, the achievements of genetics have a negative impact on human health through food consumption, expressed in the widespread distribution of genetically modified foods. When eating such products, immunity can be weakened, the general condition worsens, resistance to antibiotics, oncological diseases may appear, primarily the gastrointestinal tract (GIT) suffers.
20. Explain whether it is possible to call a virus an organism, an individual.
When a virus in a host cell reproduces its own kind, it is an organism, and very active. 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, a 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 disputes on this topic have 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 certainty of the structure (core and protein shell - capsid), its maintenance of its structure, allow us to consider the virus as a special living system - a biosystem of the organismal level, although very primitive.
21. Choose the correct answer from those offered (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 features proceeds independently of other pairs of features," - 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 the conditions of tropical regions of the Earth, cabbages do not form heads. What form of variability is manifested in this case?
a) mutational; b) combinative; c) modification (correct); d) ontogenetic.
4. An accidental appearance of a lamb with shortened legs (a deformity beneficial to a person - it does not jump over a fence) gave rise to the breed of Onkon sheep. What type of change 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. And what is the role of organisms in the microevolutionary process?
At the organismic level, for the first time, the process of fertilization and individual development of an individual appears as a process of implementing hereditary information contained in chromosomes and their genes, as well as assessing the viability of this individual by natural selection.
Organisms are expressions 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. Organisms accumulate new properties of the species. Selection exerts its effect on organisms, leaving the fittest and discarding others.
At the organismic level, the bidirectionality of the life of each organism is manifested. On the one hand, this is the possibility of an organism (individual) oriented towards survival and reproduction. On the other hand, this is to ensure the longest possible existence of its population and species, sometimes to the detriment of the life of the organism itself. This shows the important, evolutionary significance of the organismic level in nature.
Symbiotic ways of feeding organisms arose in the course of their evolution. And how do newborn individuals master this method?
They don't 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 necessary individual or substrate. For example, special receptors for the perception of another symbiotic individual or morphological structures that facilitate the very process of nutrition. Moreover, most symbiotic individuals are born near the parent organism and immediately fall into favorable conditions for development.
Symbiotic behavior is passed down from parents. For example, in birds or in mammals in relation to bacteria.
Why is it believed that a person's lifestyle is an indicator of his culture?
From how a person takes care of 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 \u200b\u200band the culture itself, behavior, lifestyle in general.
At the beginning of the XX century. became famous aphorism, which the writer Maxim Gorky in the play "At the Bottom" put into the mouth of his hero Satin: "Man - it sounds proud!" Can you currently support or refute this claim?
At present, this is a philosophical question ... Science has created a huge number of complex technical means, trying to penetrate into space and the cell, to learn the secrets of the living world, the causes of diseases, the possibility of extending the life of a person. At the same time, "perfect" means of destroying all life on Earth were developed. Is this the pride of mankind?
For a person, there are a lot of common names that reflect his inner essence: slave, fool, robber, cattle, dog, beast; at the same time: genius, creator, creator, reasonable, clever! So what is the difference between a genius and a fool? By what qualities, by what criteria should they be evaluated and compared?
Every person has a purpose on earth. Whether he understands it depends on his well-being, faith in himself, pride in himself.
Man, as a biological being, is definitely the pride of the Earth. We can think, express our emotions, speak.
But if a person understands inside 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 really pride !!!
Issue for discussion
In 1992, at the UN Conference on the Environment in Rio de Janeiro, at the level of the leaders of 179 states, including Russia, the most important documents were adopted to prevent the degradation of the biosphere. One of the programs of action of mankind in the XXI century. - "Conservation of biological diversity" has a motto: "Biological resources feed and clothe us, provide housing, medicine and spiritual food."
Express your attitude to this motto. Can you clarify it, expand it? Why is biological diversity the main 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 to our great regret, in our society, it is the relationship between these concepts that has been destroyed. Parents teach their children decency, kindness, love for the world around them, spirituality and care, but we don’t really give them this. We have lost and squandered wealth, stored and accumulated for centuries. They overthrew, consigned to oblivion the covenants, traditions, experience of past generations in relation to the surrounding world. They practically destroyed it with their own hands, their soullessness, thoughtlessness, their mismanagement.
Radiation and acid rain, crops covered with pesticides, shallow rivers, silty lakes and ponds turned into swamps, cut down forests, destroyed animals, modified organisms and products - this is our modern heritage. And now, all of a sudden, the whole world realizes that we are on the verge of death, and everyone, exactly everyone, in their place, must bit by bit, persistently and conscientiously restore, heal, grow good. Without biodiversity, WE ARE NOTHING. Biodiversity is the main 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 property 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 carry 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, which contains information about the primary structure of a single protein or rRNA and tRNA molecule.
Genome - a set of genes of the species, which includes an organism (individual). The genome is also called the set of genes characteristic of the haploid (1n) set of chromosomes of a given species of organisms, or the main haploid set of chromosomes. At the same time, the genome is considered both as a functional unit and as a species characteristic necessary for the normal development of organisms of a given species.
Genotype - a system of interacting genes of an organism (individual). The genotype expresses the totality of the genetic information of an individual (organism).
Reproduction is the reproduction of one's own kind. This property is characteristic only for 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 germ cells (gametes).
Ontogenesis is the individual development of an organism, including the whole complex of sequential and irreversible changes, 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 a biological one), maintained by 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 sickness or disease.
A virus is a unique precellular life form with a heterotrophic type of nutrition. A DNA or RNA molecule is replicated inside the affected cell.
Organism level organization of living matter - reflects the signs of individual individuals, their behavior. The structural and functional unit of the organismal level is the organism. At the organismic level, the following phenomena occur: reproduction, the functioning of the organism as a whole, ontogenesis, etc.
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, organism, population-species, biogeocenotic, biospheric.
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 is 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 take place: 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 in the cell have a characteristic structure and perform a specific function. The functions of individual organelles in the cell are interconnected and perform common life processes. In unicellular 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 protozoa - amoeba, infusoria, 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 set of cells and intercellular substances similar in origin, structure and functions forms a tissue. The tissue level is typical only for multicellular organisms. Also, individual tissues are not an independent integral organism (Fig. 3). For example, the bodies of animals and humans are made up of four different tissues (epithelial, connective, muscle, and nervous). Plant tissues are called: educational, integumentary, supporting, conductive and excretory. Recall 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 functions, 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, unite to form an organ system, for example, digestion, respiration, blood circulation, etc.
Rice. 5. Organism level
5. Organism level. Plants (chlamydomonas, chlorella) and animals (amoeba, infusoria, etc.), whose bodies consist of one cell, are an independent organism (Fig. 5). A separate individual of multicellular organisms is considered as a separate organism. In each individual organism, all the vital processes characteristic of all living organisms take place - 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 complete system organs specialized in performing 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 ontogeny. An organism can exist in close relationship with the environment.
Rice. 6. Population-species level
6. Population-species level. A set of individuals of one species or group that exists for a long time in a certain part of the range relatively apart from other sets 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. Set of organisms different types and varying complexity of the organization, adapted to the same conditions natural environment, is called biogeocenosis, or natural community. The composition of biogeocenosis includes numerous types of living organisms and environmental conditions. In natural biogeocenoses, energy is accumulated and transferred from one organism to another. Biogeocenosis includes inorganic, organic compounds and living organisms (Fig. 7).
Rice. eight. biospheric level
8. Biosphere level. The totality of all living organisms on our planet and their common natural habitat constitutes the biospheric level (Fig. 8). At the biospheric level, modern biology decides global problems, for example, determining the intensity of the formation of free oxygen by the Earth's vegetation cover or changes in the concentration of carbon dioxide in the atmosphere associated with human activities. The main role at the biospheric level is played by "living substances", that is, the totality of living organisms that inhabit 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 biospheric level, the circulation of substances and energy on Earth takes place with the participation of all living organisms of the biosphere.
levels of organization of life. population. Biogeocenosis. Biosphere.
- Currently, there are several levels of organization of living organisms: molecular, cellular, tissue, organ, organism, population-species, biogeocenotic and biospheric.
- At the population-species level, elementary evolutionary transformations are carried out.
- The cell is the most elementary structural and functional unit of all living organisms.
- A set of cells and intercellular substances similar in origin, structure and functions forms a tissue.
- The totality of all living organisms on the planet and their common natural habitat constitutes the biospheric level.
- List the levels of organization in order.
- What is fabric?
- What are the main parts of a cell?
- What organisms are characterized by the tissue level?
- Describe the organ level.
- What is a population?
- Describe the organism level.
- Name the features of the biogeocenotic level.
- Give examples of the interconnectedness of the levels of organization of life.
Complete the table showing the structural features of each level of the organization:
| Serial number |
Organization levels |
Peculiarities |
There are such levels of organization of living matter - levels of biological organization: molecular, cellular, tissue, organ, organism, 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, transfer 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 the living, a functional unit, a unit of development. This level is studied by cytology, cytochemistry, cytogenetics, 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, embryology study this level.
Organismal level of organization- this is the level of unicellular, colonial and multicellular organisms. The specificity of the organismic level is that at this level the decoding and implementation of genetic information takes place, the formation of features inherent in individuals of a given species. This level is studied by morphology (anatomy and embryology), physiology, genetics, paleontology.
Population-species level is the level of populations 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 are studied, types of relationships between organisms and populations in an ecosystem, population size, population dynamics, population density, ecosystem productivity, successions. This level studies ecology.
Allocate also biospheric level of organization living matter. The biosphere is a giant ecosystem that occupies part of the geographic envelope of the Earth. This is a mega ecosystem. The biosphere is cycling and chemical elements, as well as the conversion of solar energy.
2. Fundamental properties of living matter
Metabolism (metabolism)
Metabolism (metabolism) - a set of chemical transformations occurring in living systems that ensure their vital activity, growth, reproduction, development, self-preservation, constant contact with the environment, the ability to adapt to it and its changes. In the process of metabolism, splitting and synthesis of molecules that make up cells occur; formation, destruction and renewal cell structures and intercellular substance. Metabolism is based on interrelated processes of assimilation (anabolism) and dissimilation (catabolism). Assimilation - the 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 the deposition of synthesized substances in the reserve). Dissimilation - the processes of splitting (anaerobic or aerobic) of complex organic compounds, going with the release of energy necessary for the implementation of the vital activity of the organism. 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. chemical reactions, which are strictly ordered in time and space. The coordinated flow of a large number of reactions in a small volume is achieved by the ordered distribution of individual metabolic links in the cell (the principle of compartmentalization). Metabolic processes are regulated with the help of biocatalysts - special proteins-enzymes. Each enzyme has substrate specificity to catalyze the conversion of only one substrate. This specificity is based on a peculiar "recognition" of the substrate by the enzyme. Enzymatic catalysis differs from non-biological 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 in the process of participating in reactions. Another characteristic difference between enzymes and non-biological catalysts is that enzymes are able to accelerate reactions under normal conditions (atmospheric pressure, body temperature, etc.). All living organisms can be divided into two groups - autotrophs and heterotrophs, differing in sources of energy and necessary substances for their life. Autotrophs - 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 circulation of substances on Earth. Heterotrophs (all animals, fungi, most bacteria, some chlorophyll-free plants) are organisms that need ready-made organic substances for their existence, which, acting as food, serve as both a source of energy and a necessary "building material". A characteristic feature of heterotrophs is the presence of amphibolism in them, 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 their own kind, self-reproduction) refers to 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 the losses caused by the natural extinction of individuals, and thus maintains the preservation of the species in a number of generations of individuals. In the process of evolution of living organisms, the evolution of methods of reproduction took place. Therefore, in the numerous and diverse species of living organisms that currently exist, we find different forms of reproduction. Many types of organisms combine several methods of reproduction. It is necessary to distinguish two fundamentally different types of reproduction of organisms - asexual (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) of the mother organism. In all forms of asexual reproduction, the offspring have a genotype (set of genes) identical to the maternal one. Consequently, all the offspring of one maternal organism turns out to be genetically homogeneous and the daughter individuals have the same set of traits. In sexual reproduction, a new individual develops from a zygote formed by the fusion of two specialized germ cells (fertilization process) produced by two parental organisms. The nucleus in the zygote contains a hybrid set of chromosomes, which is formed as a result of the union of sets of chromosomes of fused gamete nuclei. In the nucleus of the zygote, thus, a new combination of hereditary inclinations (genes) is created, brought in equally by both parents. And the daughter organism developing from the zygote will have a new combination of features. 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 is an essential factor in evolution. This is a significant advantage of sexual reproduction over asexual reproduction. The ability of living organisms to self-reproduce is based on the unique property of nucleic acids to reproduce and the phenomenon of matrix synthesis, which underlies the formation of nucleic acid molecules and proteins. Self-reproduction at the molecular level determines both the implementation of metabolism in cells and the self-reproduction of the cells themselves. Cell division (self-reproduction of cells) 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 (for some viruses, in RNA). The genes encode information about the structure of synthesized proteins, enzymatic and structural. Genetic code - this is a system of "recording" information about the sequence of amino acids in the synthesized proteins using the sequence of nucleotides in the DNA molecule. The totality of all the genes of an organism is called the genotype, and the totality of traits is called the phenotype. The phenotype depends on both the genotype and the factors of the internal and external environment that affect the activity of genes 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. Due to heredity, traits are transmitted from generation to generation that ensure the adaptability of organisms to their environment. If during the reproduction of organisms only the continuity of existing signs and properties was 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 environmental conditions. There is variability in the diversity of organisms belonging to the same species. Variability can be realized in individual organisms in the course of their individual development or within a group of organisms in a series of generations during reproduction. There are two main forms of variability, which differ in the mechanisms of occurrence, the nature of the change 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 the phenotype. The basis of genotypic variability may be mutations (mutational variability) or new combinations of genes that arise in the process of fertilization during sexual reproduction. In the mutational form, changes are associated primarily with errors in the replication of nucleic acids. Thus, the emergence of new genes that carry new genetic information; new signs appear. And if the newly emerging signs are useful to the organism in specific conditions, then they are "caught 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 prerequisites for positive evolution are created. With non-hereditary (modification) variability, changes in the phenotype occur under the influence of environmental factors and are not associated with a change in the genotype. Modifications (changes in traits with modification variability) occur within the normal range of the reaction, which is under the control of the genotype. Modifications are not passed on to future generations. The value of modification variability lies in the fact that it ensures the adaptability of the organism to environmental factors during its life.
Individual development of organisms
All living organisms are characterized by the process of individual development - ontogenesis. Traditionally, ontogenesis 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 a zygote to the natural death of an 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 the "genetic program" (embodied in the genes of the chromosomes of the zygote) and is carried out in specific environmental conditions that significantly affect the process of implementing genetic information during the individual existence of an individual. In the early stages of individual development, intensive growth (increase in mass and size) occurs due to the reproduction of molecules, cells and other structures, and differentiation, i.e. appearance 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 organism. The study of the role of these factors in the process of individual development of animals and humans is of great practical importance, which increases with the intensification of anthropogenic impact on nature. In various fields of biology, medicine, veterinary medicine and other sciences, research is being widely carried out to study the processes of normal and pathological development of organisms, to elucidate the patterns of ontogenesis.
Irritability
An integral property of organisms and all living systems is irritability - the ability to perceive external or internal stimuli (impact) and adequately respond 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 rule generalizing 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 in 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 DNA → DNA informational transition. In nature, there are also transitions RNA → RNA and RNA → DNA (for example, in some viruses), as well as a change conformations proteins transferred from molecule to molecule.
Universal ways of transferring biological information
In living organisms, there are three types of heterogeneous, that is, consisting of different polymer monomers - DNA, RNA and protein. The transfer of information between them can be carried out 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 - occurring as an exception, in viruses and at mobile elements of the genome or under biological conditions experiment;
Unknown - not found.
DNA replication (DNA → DNA)
DNA is the main way information is transmitted between generations of living organisms, so the exact duplication (replication) of DNA is very important. Replication is carried out by a complex of proteins that unwind chromatin, then a double helix. After that, DNA polymerase and its associated proteins build an identical copy on each of the two strands.
Transcription (DNA → RNA)
Transcription is a biological process, as a result of which the information contained in a DNA segment is copied onto a synthesized molecule. messenger RNA. Transcription is carried out transcription factors and RNA polymerase. AT 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 translation process. AT prokaryotic In cells, the process of transcription and translation is not spatially separated, and these processes are conjugated. AT eukaryotic transcription site in cells cell nucleus separated from the broadcast site ( 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 in this case occurs in the “reverse” direction relative to transcription.
The idea of reverse transcription was initially very unpopular, as 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 and virulent phages are capable of transduction, the latter, however, destroy the bacterial population, so transduction with their help does not have 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:
Ability to autonomously replicate in a host cell (usually bacterial or yeast)
The presence of a selectable marker
Availability of convenient restriction sites
The most common vectors are bacterial plasmids.
The following levels of life organization are distinguished: molecular, cellular, organ-tissue (sometimes they are separated), organismic, population-species, biogeocenotic, biospheric. Live 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 overlying ones.
So complex organic molecules are part of the cells and determine their structure and vital activity. 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 biological species. The community is represented by interacting populations of different species. Community and environment form a biogeocenosis (ecosystem). The totality of ecosystems of the planet Earth forms its biosphere.
At each level, new properties of living things arise, which are absent at the underlying level, their own elementary phenomena and elementary units are distinguished. At the same time, the levels largely reflect the course of the evolutionary process.
The allocation of levels is convenient for studying life as a complex natural phenomenon.
Let's take a closer look at each level of organization of life.
Molecular level
Although molecules are made up of atoms, the difference between living matter and non-living matter begins to manifest itself only at the level of molecules. Only found in living organisms a large number of complex organic substances - biopolymers (proteins, fats, carbohydrates, nucleic acids). However molecular level The organization of living things also includes inorganic molecules that enter cells and play an important role in their life activity.
The functioning of biological molecules underlies the living system. At the molecular level of life, metabolism and energy conversion are manifested as chemical reactions, the transfer and change of hereditary information (reduplication and mutations), as well as a number of other cellular processes. Sometimes the molecular level is called the molecular genetic level.
Cellular level of life
It is the cell that is the structural and functional unit of the living. There is no life outside the cell. Even viruses can exhibit the properties of a living being only once they are in the host cell. Biopolymers fully show their reactivity when organized in 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 conjugated.
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 that have 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, a protective, basic and conductive tissue. In animals - epithelial, connective, muscular and nervous. The fabrics may include a list of subfabrics.
An organ usually consists of several tissues, united among themselves in 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.
Organismal level of organization of living
Along with the cellular at the organismal (or ontogenetic) level, separate structural units are distinguished. Tissues and organs cannot live independently, organisms and cells (if unicellular organism) can.
Multicellular organisms are made up of organ systems.
At the organismic level, such phenomena of life as reproduction, ontogeny, metabolism, irritability, neuro-humoral regulation, homeostasis are manifested. In other words, its elementary phenomena constitute regular changes in 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 share a common gene pool. Within a species, they can exchange genes, that is, they are genetically open systems.
In populations, elementary evolutionary phenomena occur, ultimately leading to speciation. Living nature can evolve only in supra-organismal levels.
At this level, the potential immortality of the living arises.
Biogeocenotic level
Biogeocenosis is an interacting set of organisms of different species with different environmental factors. Elementary phenomena are represented by matter-energy cycles, provided primarily by living organisms.
The role of the biogeocenotic level consists in the formation of stable communities of organisms of different species, adapted to living together in a certain habitat.
Biosphere
The biospheric level of life organization is a higher-order system of life on Earth. The biosphere encompasses all manifestations of life on the planet. At this level, the global circulation of substances and the flow of energy (covering all biogeocenoses) take place.