home Botany The leading role in evolution is played by the following. View, its criteria

The leading role in evolution is played by the following. View, its criteria

Biology test OPTION - 1. 1. The main merit of Charles Darwin is: A) formulating biogenetic law; C) theory development natural selection; B) creation of the first evolutionary theory; D) creation of the law of natural series. 2. Most...

Biology test OPTION - 1. 1. The main merit of Charles Darwin is: A) the formulation of the biogenetic law; C) development of the theory of natural selection; B) creation of the first evolutionary theory; D) creation of the law of natural series. 2. Ch. Darwin considered the most intense form of the struggle for existence: A) the struggle with adverse conditions; B) interspecific; B) intraspecific; D) all of the listed forms equally. 3. Natural selection operates at the level of: A) an individual organism; B) type; B) populations; D) biocenosis. 4. Homologous organs are: A) a cat's paw and a fly's leg; C) reptile scales and bird feathers; B) human eye and spider eye; D) butterfly wing and bird wing. 5. Ape people include: A) Cro-Magnon; B) pithecanthropus; B) Australopithecus; D) Neanderthal. 6. An environmental factor that goes beyond endurance is called: A) stimulating; B) abiotic; B) limiting; D) anthropogenic 7. Eukaryotes: A) capable of chemosynthesis; C) do not have many organelles; B) have circular DNA; D) have a nucleus with its own shell. eight. common feature plant and animal cells is: A) heterotrophy; C) the presence of chloroplasts; B) the presence of mitochondria; D) the presence of a rigid cell wall. 9. Biopolymers are: A) proteins; B) nucleic acids; B) polysaccharides; D) all of the above. 10. Uracil forms a complementary bond with: A) adenine C) cytosine B) thymine D) guanine. 11. Glycolysis is called: A) the totality of all processes of energy metabolism in the cell; B) oxygen-free breakdown of glucose; C) complete breakdown of glucose; D) polymerization of glucose with the formation of glycogen. 12. The order of the stage of mitosis is as follows: A) metaphase, telophase, prophase, anaphase; C) prophase, metaphase, telophase, anaphase; B) prophase, metaphase, anaphase, telophase; D) telophase, prophase, metaphase, anaphase; 13. Chromosome doubling occurs in: A) interphase C) metaphase B) prophase D) telophase 14. In the anaphase of mitosis, a divergence occurs: A) daughter chromosomes C) non-homologous chromosomes B) homologous chromosomes D) cell organelles. 15. Of the listed animals, the largest egg is in: A) sturgeon C) lizard B) frog D) chicken. 16. From the ectoderm are formed: A) muscles C) skeleton B) lungs D) sense organs. 17. With Mendeleev monohybrid crossing, the proportion of individuals with at least one recessive gene in the second generation will be: A) 25% B) 50% C) 75% D) 100%

18. Linked genes are genes located in: A) one chromosome C) sex chromosomes B) homologous chromosomes D) autosomes. 19. Mutations manifest themselves phenotypically: A) always C) only in the homozygous state B) only in the heterozygous state D) never. 20. Polyploidy consists in: A) a change in the number of individual chromosomes; B) a change in the structure of chromosomes; B) a multiple change in the haploid number of chromosomes; D) changes in the structure of individual genes. ANSWER: 1 - C, 2 - B, 3 - B, 4 - C, 5 - C, 6 - B, 7 - D, 8 - B, 9 - D, 10 - A, 11 - B, 12 - B, 13 - A, 14 - A, 15 - D, 16 - D, 17 - C, 18 - A, 19 - C, 20 - B. OPTION - 2 1. According to Ch. Darwin, the driving forces of evolution are: A) struggle for existence; B) natural selection; B) hereditary variability; D) all of the above. 2. The following type of variability plays a leading role in evolution: A) certain; B) group; B) modification; D) mutational. 3. The driving form of selection usually leads to: A) the destruction of individuals with deviations; B) the expansion of the previous reaction rate; from the previous rate of reaction; B) narrowing of the previous norm of reaction; D) shift of the previous rate of reaction. 4. Similar organs are: A) crayfish gills and fish gills; C) birch leaves and cactus needles; B) a dog's paw and a bird's wing; D) all of the listed pairs. 5. In the era of glaciation lived: A) Cro-Magnons; B) synanthropes; B) Neanderthals; D) all of the above. 6. The productivity of an ecosystem is: A) its total biomass; C) total biomass of producers; B) the growth of this biomass per unit of time; D) total biomass of consumers. 7. In prokaryotic cells there are: A) nuclei; B) mitochondria; B) ribosomes; D) all of the listed organelles. 8. Leukoplasts are cell organelles in which: A) protein synthesis is carried out; C) there are pigments of red and yellow color; B) the process of photosynthesis is carried out; D) starch builds up. 9. Nucleotides in the strands of the DNA molecule are connected by the following bond: A) covalent; B) peptide; B) hydrogen; D) disulfide bridges. 10. Transcription is: A) the synthesis of an i-RNA molecule; B) the delivery of amino acids to ribosomes along the template of one of the DNA chains; during protein synthesis; B) transfer of information from i-RNA to protein D) the process of assembling a protein molecule. during its synthesis; 11. Synthesis of ATP in the cell occurs in the process of: A) glycolysis; B) cellular respiration; B) photosynthesis; D) all of the above. 12. The longest phase of mitosis is:

A) prophase; B) anaphase; B) metaphase; D) telophase. 13. Reduction of the number of chromosomes occurs during: A) anaphase of mitosis; C) II division of meiosis; B) I division of meiosis; D) in all of the above cases. fourteen. biological significance meiosis is to ensure: A) genetic stability; C) genetic variability; B) tissue regeneration and increase D) asexual reproduction. the number of cells in the body; 15. The nervous system is formed from: A) ectoderm; B) mesoderm; B) endoderm; D) there is no correct answer. 16. From the mesoderm are formed: A) lungs; B) circulatory system B) nervous system; D) sense organs. 17. How many types of gametes form diheterozygous individuals: A) one; At four; B) two; D) there is no correct answer. 18. Mutational variability includes: A) changes in chromosomes; C) changes that are inherited; B) changes in genes; D) all of the above. 19. The main source of combinative variability is: A) chromosome crossing B) independent chromatid segregation In prophase I of meiotic division; in anaphase II of meiotic division; B) independent discrepancy D) all of the above processes equally. homologous chromosomes in anaphase I of meiotic division; 20. Interline hybridization of cultivated plants leads to: A) maintaining the same productivity; B) increase productivity; B) cleavage of new features; D) fixing signs. ANSWER: 1 - D, 2 - D, 3 - D, 4 - A, 5 - B, 6 - B, 7 - B, 8 - D, 9 - A, 10 - A, 11 - D, 12 - A, 13 - B, 14 - C, 15 - A, 16 - C, 17 - C, 18 - D, 19 - D, 20 - C.

21.01.2017 2059 179 Salykova Mira Markenovna

OPTION - 2
1. According to Ch. Darwin, the driving forces of evolution are:
A) the struggle for existence; B) natural selection;
B) hereditary variability; D) all of the above.
2. The following type of variability plays a leading role in evolution:
A) certain B) group;
B) modification; D) mutational.
3. The driving form of selection usually leads to:
A) the destruction of individuals with deviations; B) the expansion of the previous norm of reaction;
from the previous rate of reaction;
B) narrowing of the previous norm of reaction; D) shift of the previous rate of reaction.
4. Similar bodies are:
A) crayfish gills and fish gills; C) birch leaves and cactus needles;
B) a dog's paw and a bird's wing; D) all of the listed pairs.
5. In the era of glaciation lived:
A) Cro-Magnons B) synanthropes;
B) Neanderthals; D) all of the above.
6. The productivity of an ecosystem is called:
A) its total biomass; C) total biomass of producers;
B) the growth of this biomass per unit of time; D) total biomass of consumers.
7. In prokaryotic cells there are:
A) nuclei B) mitochondria;
B) ribosomes; D) all of the listed organelles.
8. According to the views of A.I. Oparin, the main sources of energy for abiogenic synthesis organic matter from inorganic to ancient earth were:
a) electric projectiles; b) ultraviolet radiation;

9. Life on Earth arose:
a) originally on sushi; b) initially in the ocean;
10. The panstermia hypothesis suggests
a) life is brought to our planet from outside;
b) life arose repeatedly from non-living matter;
c) the gradual emergence of life on Earth from inorganic substances
by long-term abiogenic molecular evolution;
d) life has always existed.
11. The gene refers to the structural and functional unit of the level of organization of life
A) organismic B) molecular-genetic C) organoid-cellular D) population-species
12. A population is a collection of individuals of a particular species occupying a certain territory and

13 The main reason for the biological regression of many species at present is:
A) climate change B) human economic activity
C) change in relief D) increase in the number of predators.
14. The science of cytology studies:

15. A reservoir inhabited by various species of plants and animals is:
16. The theory of abiogenesis was supported by:
a) Aristotle b) F. Redi; c) L. Pasteur; d) K. Linney
17. Changes that are not inherited and arise as adaptations to the external environment are called:
A) indefinite B) individual C) mutational
D) modification
18. Deoxyribonucleic acid is the level of organization of wildlife:
19. The ancient people include:

20. Fitness in the process of evolution arises as a result of:

OPTION - 3
1. Deoxyribonucleic acid is the level of organization of wildlife:
A) cellular; B) molecular;
B) organismic; D) population
2. The science of cytology studies:
A) the structure of cells of unicellular and multicellular organisms;
B) the structure of organs and organ systems of multicellular organisms;
C) the phenotype of organisms from different kingdoms;
D) plant morphology and features of their development.
3. The ancient people include:
A) Neanderthal B) Pithecanthropus
C) Sinanthropus D) Cro-Magnon.
4. There is competition between elk and bison, as they:
A) eat the same food B) have approximately the same body parameters
C) have few offspring D) belong to the class of mammals.
5. Fitness in the process of evolution arises as a result of:
A) geographical isolation B) interaction of the driving forces of evolution
C) mutational variability D) artificial selection.
6. A reservoir inhabited by various species of plants and animals is:
A) biogeocenosis B) noosphere C) biosphere D) agroecosystem.
7. Life on Earth arose:
a) originally on sushi; b) initially in the ocean;
c) on the border of land and ocean; d) simultaneously on land and ocean.
8. Deoxyribonucleic acid is the level of organization of wildlife:
A) cellular; B) molecular; B) organismic; D) population
9. A population is a collection of individuals of a particular species occupying a certain territory and
A) have a common gene pool
B) similar to each other in all respects of the external structure
C) having various obstacles for free crossing
D) do not compete with each other for food and other favorable conditions environment
10. According to the views of A.I. Oparin, the main sources of energy for the abiogenic synthesis of organic substances from inorganic substances on the ancient Earth were:
a) electric projectiles;
b) ultraviolet radiation;
c) thermal radiation from volcanic eruptions;
d) energy chemical reactions
11. New species in nature arise as a result of interaction:
BUT) hereditary variability, struggle for existence, natural selection
B) non-hereditary changes and seasonal changes in nature
C) adaptability of organisms and artificial selection
D) abiotic environmental factors
12. . Ch. Darwin considered the most intense form of struggle for existence:
A) the fight against adverse conditions; B) interspecific;
B) intraspecific; D) all of the listed forms equally.

Option 1
ANSWER: 1 - C, 2 - B, 3 - B, 4 - C, 5 - C, 6 - B, 7 - D, 8 - B, 9 - D, 10 - B,
11 - C, 12 - C, 13 - B, 14 - C, 15 - A, 16 - A, 17 - B, 18 - A, 19 - A,
20 - G.

Option 2
ANSWER: 1 - D, 2 - D, 3 - D, 4 - A, 5 - B, 6 - B, 7 - B, 8 - D, 9 - A, 10 - A,
11 - B, 12-A, 13-B, 14-A, 15-A, 16-A, 17-G, 18-B, 19-A, 20-B

Option 3
Answers: 1 - B, 2 - A, 3 - a, 4 - C, 5 - B, 6 - A, 7 - B, 8 - B, 9 - A
10 - D, 11 - A, 12 - B, 13 - C, 14 - A, 15 - B, 16 - D, 17 - A, 18 - A,
19 - B, 20 - B.

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Test on the topic "The doctrine of evolution organic world»
1 OPTION

TASK #1

LEVEL "A" . When completing tasks of this level, choose one correct answer from the four proposed.

1. What species criterion does the following description correspond to: the great tit lives in the crowns of trees, feeds on large insects and their larvae?

A) geographic

B) environmental

B) morphological

D) genetic

2. Ch. Darwin considered the most intense form of struggle for existence:

A) dealing with adverse conditions

B) intraspecific

B) interspecies

D) all of the listed forms equally

3. Natural selection operates at the level of:

A) individual organism

B) populations

B) kind

D) biocenosis

4. What aromorphoses allowed reptiles to fully master the ground-air environment

A) cornea developed lungs

B) five-fingered limb, live birth

C) protective coloration, the ability to regenerate

D) four-chambered heart, warm-bloodedness

5. The leading role in evolution is played by the following type of variability:

A) certain

B) modification

B) group

D) mutational

6. The main factor that unites individuals of the same species into a separate population:

A) free crossing of individuals with each other

B) the similarity of the external and internal structure individuals with each other

C) the same chromosome set of individuals: the shape and number of chromosomes

D) the total territory (range) occupied by individuals in nature

7. Large systematic groups in the process of evolution arise, as a rule, by:

A) aromorphosis

B) idioadaptation

B) general degeneration

D) directed evolution

8. An example of the action of a stabilizing form of natural selection:

A) the existence of a relict cross-finned coelacanth fish

B) the appearance of a dark-colored form in the population of the birch moth butterfly

C) the appearance of early-flowering and late-flowering races of a large rattle in mowed meadows

D) the appearance of long-winged and wingless insects on oceanic islands blown by the winds

9. The driving form of selection usually results in:

A) to the destruction of individuals with deviations from the previous norm of reaction

B) narrowing the former form of the reaction

C) expansion of the previous rate of reaction

D) a shift in the previous rate of reaction

10. Microevolution leads to the formation of new:

A) family groups

B) subspecies and species

B) giving birth

D) orders and families

11. An increase in the number of a species in nature indicates its

A) biological progress

B) development along the path of degeneration

B) biological regression

D) development along the path of aromorphosis

12. The fight against adverse environmental conditions as a result of evolution:

A) reduces the resistance of organisms

B) leads to the survival of the most viable individuals

B) leads to the extinction of the species

D) contributes to the improvement of the properties of the species

13. Hereditary variability in the process of evolution:

A) create new species

B) populations

B) kind

D) biocenosis

14. Isolation is an evolutionary factor that:

A) does not affect the rate of speciation

B) slows down the process of fitness formation

C) does not prevent the mixing of the population within the species

D) accelerates the evolutionary process

15. The result of natural selection is not:

A) adaptability of organisms to the environment

B) the diversity of the organic world

B) struggle for existence

D) improvement of the organization of living beings

TASK #2

LEVEL "B". Select multiple answers from the six. Write the selected letters in alphabetical order.

B 1. Adaptations to life in the water, formed in the process of evolution in whales:

A) the transformation of the forelimbs into flippers

B) breathing oxygen dissolved in water

B) breathing oxygen in the air

D) streamlined body shape

D) developed thick subcutaneous fat layer

E) constant body temperature

IN 2. Establish a correspondence between the directions of evolution of systematic groups and the features characterizing them:

CHARACTERISTICS: DIRECTIONS OF EVOLUTION:

1) variety of species A) biological progress

2) restricted area B) biological regression

3) a small number of species

4) wide ecological adaptations

5) wide range

6) decrease in the number of populations

2 OPTION

TASK #1

LEVEL "A". When completing tasks of this level, choose one correct answer out of four

1. Give an example of idioadaptations:

A) the emergence of a seed in gymnosperms

B) the appearance of the fetus in flowering

C) occurrence in flowering nectaries that attract insects

D) the appearance of photosynthesis in plants

2. Homologous organs in different organisms were formed as a result of

A) convergence

B) idioadaptation

B) divergence

D) aromorphosis

3. In geographic speciation, the formation of a new species occurs as a result of:

A) disintegration or expansion of the original range

B) artificial selection

C) isolation of populations within the old range

D) genetic drift

4. What are the consequences of motive selection?

A) preservation of old species

B) maintaining the reaction rate

C) the emergence of new species

D) elimination of individuals with new mutations

5. The formation of new species in nature occurs as a result of:

A) methodical selection

B) artificial selection

B) human activities

D) interactions of the driving forces of evolution

6. Point out the incorrect statement: “In the process of evolution, the struggle with adverse conditions leads. . ."

A) increase the resistance of organisms

B) species extinction

B) the survival of the most viable individuals

D) improving the look

7. The factor of evolution, the basis of which is the emergence of barriers to the free crossing of individuals, is called:

A) modification

B) natural selection

B) insulation

G) population waves

8. What are the consequences of stabilizing selection?

A) preservation of old species

B) maintaining the reaction rate

C) the emergence of new species

D) preservation of individuals with unchanged characteristics

9. Among the driving forces of evolution leading to the emergence of adaptations in individuals to the environment, the guiding character has:

A) natural selection

B) artificial selection

B) isolation

D) struggle for existence

10. An example of aromorphosis is:

A) flattening of the body in bottom fish

B) protective coloration

D) the occurrence of the sexual process

11. Idio adaptations include:

A) multicellularity

B) four-chambered heart of mammals

B) needle-like leaves of desert plants

D) all of the above evolutionary changes

12. As a result of the interaction of the driving forces of evolution, the following occurs:

A) reproduction of organisms

B) the formation of new species in nature

B) mutation process

D) isolation of populations

13. Natural selection is considered the guiding factor of evolution, since individuals are preserved as a result of it:

A) with neutral changes

B) various changes

B) minor hereditary changes

D) changes corresponding to the habitat

14. The ability of living beings to produce a large number of descendants and limited habitats and life resources are the immediate causes of:

A) hereditary variation

B) struggle for existence

B) extinction

D) speciation

15. The struggle for existence plays a big role in evolution:

A) preserves individuals predominantly with useful traits

B) preserves individuals with any hereditary changes

B) supplies material for selection

D) aggravates the relationship between individuals

TASK #2

LEVEL "B"

B 1. Select several answers from the six and write them down in alphabetical order.

The result of evolution is:

A) the emergence of new species in changing environmental conditions

B) the emergence of new drought-resistant plant varieties

C) breeding of highly productive breeds of cattle

D) the formation of new adaptations to life in changed conditions

E) preservation of old species in stable habitat conditions

E) obtaining highly productive broiler chickens

B 2. Establish a correspondence between the characteristics of the selection and its type:

CHARACTERISTICS TYPE OF SELECTION

1) acts constantly in nature A) natural

2) preserves individuals with signs, B) artificial

of interest to a person

3) preserves individuals with traits that are useful to them

4) provides the formation of fitness

5) leads to the emergence of new species

6) contributes to the creation of new breeds of animals

KEY TO COMPLETING TASKS ON THE TOPIC

"FOUNDATIONS OF THE DOCTRINE OF EVOLUTION"

1 OPTION

TASK № 1.

LEVEL "A" ANSWER: 1B, 2B, 3B, 4A, 5D, 6D, 7A, 8A, 9D, 10B, 11A, 12D, 13B, 14D, 15B

TASK № 2.

LEVEL "B".

B1 - A, D, D

B2 - 1A, 2B, 3B, 4A, 5A, 6B

TASK № 3.

LEVEL "C".

C 1. Answer elements:

1) made it possible to use different feeds for food;

2) contributed to the weakening of competition;

3) in connection with the divergence of characters and the isolation of populations, the formation of new species occurred.

OPTION #2

TASK №1.

LEVEL "A" ANSWER: 1C, 2B, 3A, 4C, 5D, 6C, 7C, 8A, 9A, 10D, 11C, 12B, 13D, 14B, 15D

TASK № 2.

LEVEL "B"

B 1 - A. G, D

B 2 - A1, B2, C1, G1, D1, E1

TASK #3

LEVEL "C"

C 1. Answer elements:

1) type of coloring - patronizing - merging with the background sea day;

2) the ability to change the color of the upper side of the body makes the fish invisible against the background of the ground, allowing you to hide from enemies and possible prey;

3) fitness is broken when the fish moves, it becomes available to enemies. This is the relative nature of adaptation.

CRITERIA FOR EVALUATION

For each correctly completed level "A" task, one point is given. Maximum amount points that can be obtained - fifteen.

For a correctly completed task B1, you can get three points, i.e. one point for each answer. For completing task B2, you can also get a maximum of three points, i.e. for six answers 0.5 points each. In total, the correct performance of the tasks of part "B" gives six points.

For completing task No. 3 (level "C"), you can get three points if the answer is correct and complete, includes all elements of the answer, does not contain biological errors.

"5" - 24 - 21 points

"4" - 20 - 16 points

"3" - 15 - 10 points

"2" - 9 points or less

Textbook for grades 10-11

Chapter XI. Mechanisms of the evolutionary process

Charles Darwin in his classic work "The Origin of Species" solved the problem of the main driving forces (factors) of the evolutionary process. He singled out the following factors: heredity, variability, the struggle for existence and natural selection. In addition, Darwin pointed out the important role of limiting the free interbreeding of individuals due to their isolation from each other, which arose in the process of evolutionary divergence of species.

Modern knowledge about evolution and its factors has developed into the so-called synthetic theory of evolution, which is the result of the development of Darwinism, genetics, ecology and other biological sciences.

The evolutionary theory proceeds from the fact that the elementary evolutionary unit, that is, the minimum cell that is capable of historical change (evolve), is the population.

§ 45. The role of variability in the evolutionary process

All individuals of the same species of animals and plants are more or less different from each other. The variability of organisms is an important factor in the course of the evolutionary process.

mutational variability. Mutational variability plays the role of the main supplier of hereditary changes. It is she who is the primary material of all evolutionary transformations. One of the common types of genomic mutations is polyploidy, which is important in plant evolution. Polyploid plant species often occupy arctic and alpine zones. It is believed that this is due to their increased resistance to adverse environmental factors.

Chromosomal mutations also play an important evolutionary role. First of all, it is necessary to point out the duplication of genes in one chromosome. It is thanks to the doubling of genes that genetic material accumulates in the process of evolution. The increasing complexity of the organization of living things in the course of historical development largely relied on an increase in the amount of genetic material. Suffice it to say that the amount of DNA in a cell in higher vertebrates is about 1000 times greater than in bacteria. Another type of chromosomal mutation, which is quite often found in animals and plants, is the displacement of a chromosome segment.

Individuals heterozygous for such mutations often have reduced fertility, while homozygotes reproduce normally. Some scientists believe that the appearance of such mutations can break the genetic unity of the species and lead to isolation within its reproductively isolated populations.

SERGEI SERGEEVICH CHETVERIKOV (1882-1959) - Russian scientist, evolutionist and geneticist. His work gave rise to the modern synthesis of genetics and classical Darwinism.

The most common type of mutations are genes. They play a very important role in the evolutionary process. Mutations of individual genes are rare. A gene mutation occurs on average in one in 100,000 gametes. But since the number of genes in an organism (for example, mammals) is about 40,000, almost every individual carries a newly emerged mutation. Most mutations are recessive, dominant mutations occur much less frequently. Dominant and recessive mutations behave differently in populations. Dominant mutations, even if they are in a heterozygous state, appear in the phenotypes of individuals already in the first generation and are subject to natural selection. Recessive mutations appear in the phenotype only in the homozygous state.

A recessive mutation, before it manifests itself in the phenotype of homozygotes, must accumulate in significant numbers in the population. This idea was first expressed by the domestic geneticist S. S. Chetverikov. He was the first scientist to take a major step towards the unification of genetics with evolutionary theory. In 1926, Chetverikov published the famous work "On Some Moments of the Evolutionary Process from the Point of View of Modern Genetics", which began a new stage in the development of evolutionary theory.

S. S. Chetverikov made an important conclusion about the saturation of natural populations large quantity recessive mutations. He wrote that a population, like a sponge, absorbs recessive mutations while remaining phenotypically homogeneous. The existence of such a hidden reserve of hereditary variability creates the possibility for evolutionary transformations of populations under the influence of natural selection. As I. I. Shmalgauzen showed, the very ability of populations to accumulate genetic variability is the result of natural selection.

Recently, thanks to the advances in molecular genetics and developmental genetics, it has become increasingly clear what a huge role is played in evolution by mutations that occur not in the structural (protein-coding) genes themselves, but in the regulatory regions of these genes. They can modify the level of transcription of structural genes, the time and place of their switching on and off, creating a huge variety of forms and functions of organisms. Significant morphological differences between classes of vertebrates depend on the accumulation small mutations in regulatory elements.

Let's consider a simple example. The size and position of the chest in chicken, mouse, and boa constrictor are controlled by the same structural gene. The nucleotide sequence in this gene is the same in all three species (as in all other vertebrates). However, the changes that have occurred in its regulatory elements lead to the fact that in the boa constrictor this gene works in almost all cells of the notochord of the embryo, in the mouse - in the anterior part, and in the chicken - in the back of the notochord. As a result rib cage the boa constrictor is formed from the head almost to the tip of the tail, in the mouse it is closer to the head, and in the chicken it is closer to the tail.

In natural populations, a huge number of mutations in the regulatory elements of various structural genes has been accumulated.

Combination variability. As you already know, combinative variability is a consequence of the crossing of homologous chromosomes, their random divergence in meiosis and the random combination of gametes during fertilization. Combinative variability leads to the appearance of an infinitely large variety of genotypes and phenotypes. It serves as an inexhaustible source of hereditary diversity of species and the basis for natural selection. Assuming that each pair of homologous chromosomes has only one pair allelic genes, then for a person whose haploid set of chromosomes is 23, the number of possible gametes will be 2 23, and the number of possible genotypes - 3 23. Such a huge number of genotypes is 20 times greater than the number of all people on Earth. However, in reality, homologous chromosomes differ in several genes, and the phenomenon of crossover is not taken into account in the calculation. Therefore, the number of possible genotypes is expressed by an astronomical number, and it can be safely stated that the appearance of two identical people is almost unbelievable. Identical twins are an exception.

The enormous genotypic and, consequently, phenotypic diversity in natural populations is the initial evolutionary material with which natural selection operates.

What kind of variability, in your opinion, plays a leading role in evolution? Justify the answer.
Describe the role of variability in the evolutionary process.
How can one explain the phenotypic homogeneity of populations of one species? Can it be argued that the gene pools of populations of the same species are the same?
What biological processes occurring in the body underlie combinative variability?

The theory of evolution by Ch. Darwin and A. Wallace.

Basic provisions:

1. All kinds of living organisms arose naturally.

2. Organisms slowly and gradually transformed and improved.

3. The basis for the transformation of species is variability, heredity and natural selection. Selection is carried out through the interactions of organisms with each other and environmental factors. These interactions are called the struggle for existence.

4. Individuals that are most adapted to changing environmental conditions survive and give full-fledged offspring.

Synthetic theory of evolution - this is a rethinking of a number of provisions of Darwinism from the standpoint of genetics (S. Chetverikov, J. Haldane, N. Timofeev-Resovsky, R. Fisher). It is characterized as a theory of evolution occurring through natural selection of traits determined genetically.

Basic provisions:

1. The elementary unit of evolution is the population.

2. The material for evolution is mutational and combinational variability.

3. Natural selection is considered as the main reason for the development of adaptations, speciation and the origin of supraspecific taxa.

4. A species is a group of populations reproductively isolated from populations of other species.

5. Speciation consists in the emergence of genetic isolating mechanisms and is carried out in conditions of geographic isolation.

The process of formation of new genera from species, from genera to families, from families to orders, etc. called macroevolution. Unlike microevolution occurring within a population, macroevolution is supraspecific and very long-term evolution.

The proof of evolutionary processes are paleontological, morphological, embryological and biochemical data.

There are three main directions of evolution.

Aromorphosis – evolutionary changes leading to a qualitatively new level of organization (multicellularity, central nervous system, photosynthesis). Thanks to aromorphosis, new large taxonomic units arise: types (departments), classes.

Idioadaptation - small evolutionary changes, expressed in adaptation to the environment. There is no increase in the level of organization. Thanks to idioadaptation, small taxonomic groups are formed: species, genera, families.

Mutations constantly arise in populations under the influence of factors and cause changes in its gene pool. population waves- this is a phenomenon of fluctuations in the number of populations, which are associated with periodic changes in the intensity of environmental factors (change of seasons, precipitation, temperature fluctuations).

Insulation contributes to the prevention of interbreeding between individuals of different parts of the population and leads to a divergence of characters within the same species.

Geographic isolation leads to a rupture of a single range of a species into separate parts and prevents crossing. The reasons for its appearance are the emergence of mountains, new rivers, straits, etc.

Environmental isolation based on differences in dispersal or breeding times. For example, some species of salmon spawn in a year, and in the same rivers one population of fish spawns in one year, and another in another.

biological isolation associated with differences in the structure of the genital organs, in marriage songs, courtship rituals, emitted odors, etc.

The greatest importance in the evolutionary process is natural selection. It plays a creative role in nature, distinguishing from undirected hereditary changes only those that lead to the formation of new groups of individuals that will be more adapted to new environmental conditions.

Soviet biologist I.I. Schmalhausen developed (1946) the concept of group selection - the survival of populations, species, genera, families, orders, etc. But since group selection occurs on the basis of the experience of the organisms that make up these groups, the leading role in evolution is also played by individual natural selection - the selection of the most adapted individuals.