Which genes are active in the first. Types of gene interactions

The main forms of interaction of non-alelic genes are complementarity, epistasis, and polymeria. They mainly modify the classical splitting formula for the phenotype, established by G. Mendel for dihybrid crossing (9: 3: 3: 1).

Complementarity(Latin complementum - additions). Complementary, or complementary, are called non-allelic genes, which alone do not show their action, but, when present in the genotype at the same time, predetermine the development of a new trait. In sweet pea, the color of flowers is due to two dominant non-allelic genes, of which one gene (A) provides the synthesis of a colorless substrate, the other (B) - synthesis of a pigment. Therefore, when crossing plants with white flowers (AAbb x aaBB), all plants in the first generation F1 (AaBb) have colored flowers, and in the second generation F2 splitting occurs according to the phenotype in a ratio of 9: 7, where 9/16 plants have colored flowers and 7 / 16 - unpainted.

In humans, normal hearing is due to the complementary interaction of two dominant non-allelic genes D and E, of which one determines the development of the curl, the other the auditory nerve. People with genotypes D – E– have normal hearing, those with genotypes D – ee and ddЕ– are deaf. In a marriage where the parents are deaf (DDee ´ ddEE), all children will have normal hearing (DdEe).

Epistasis - interaction of non-allelic genes, in which one gene suppresses the action of another, non-allelic, gene. The first gene is called epistatic, or suppressor (inhibitor), the other, non-allelic, gene is called hypostatic. If the epistatic gene is dominant, epistasis is called dominant (A> B). Conversely, if the epistatic gene is recessive, the epistasis is recessive (aa> B or aa> cc). The interaction of genes in epistasis is the opposite of complementarity.

An example of dominant epistasis... In chickens, the dominant allele C of one gene determines the development of feather coloration, but the dominant allele I of the other gene is its suppressor. Therefore, chickens with genotype I – C– are white, and chickens with genotypes IICC and IICc are stained. In the crossing of white chickens (ІІСС x іісс), the hybrids of the first generation F1 will turn out to be white, but when crossing F1 with each other in the second generation F2, splitting will take place according to the phenotype in a ratio of 13: 3. Of the 16 individuals, 3 will be stained (ііСС and ііСс), since they lack a dominant suppressor gene and have a dominant gene for coloration. The other 13 will be white.

An example of recessive epistasis there may be a Bombay phenomenon - an extraordinary inheritance of blood groups of the ABO system, first identified in an Indian family. In a family where the father had a blood group I (O), and have a ІІІ (B), a girl with a group I (O) was born, she married a man with a blood group II (A) and they had two girls: one of the blood group IV (AB), the other with I (O). The birth of a girl with IV (AB) blood group in a family where the father had II (A), and the mother - I (O) was extraordinary. Geneticists explained this phenomenon as follows: a girl with group IV (AB) inherited the IA allele from her father, and the IB allele from her mother, but the mother did not phenotypically manifest the IB allele, since her genotype contained a rare recessive epistatic gene s in a homozygous state, which provoked the phenotypic manifestation of the IB allele.

Hypostasis- interaction of non-alelic genes, in which the dominant gene of one allelic pair is suppressed by an epistatic gene from another allelic pair. If gene A suppresses gene B (A> B), then in relation to gene B, the interaction of non-allelic genes is called hypostasis, and in relation to gene A - epistasis.

Polymerism- interaction of non-allelic genes, in which one and the same trait is controlled by several dominant non-allelic genes, which act on this trait unambiguously, equally, enhancing its manifestation. Such unambiguous genes are called polymeric (multiple, polygenes) and are denoted by one letter Latin alphabet but with different numeric indexes. For example, dominant polymeric genes - A1, A2, A3, etc., recessive - a1, a2, a3, etc. Accordingly, the genotypes are designated - A1A1A2A2A3A3, a1a1a2a2a3a3. Traits that are controlled by polygenes are called polygenic, and the inheritance of these traits is polygenic, in contrast to monogenic, where a trait is controlled by one gene. The phenomenon of polymerization was first described in 1908 by the Swedish geneticist G. Nilsson-Ehle when studying the inheritance of the color of wheat grain.

Polymerism is cumulative and non-cumulative.. With cumulative polymerization, each gene individually has a weak effect (weak dose), but the number of doses of all genes in the final result is summed up, so that the degree of expression of the trait depends on the number of dominant alleles. The type of polymerization in humans is inherited by height, body weight, skin color, mental abilities, and blood pressure. Thus, human skin pigmentation is determined by 4-6 pairs of polymer genes. In the genotype of the indigenous inhabitants of Africa, there are predominantly dominant alleles (P1P1P2P2P3P3P4P4), in representatives of the Caucasoid race - recessive (p1p1p2p2p3p3p4p4). From the marriage of a black and white woman, children are born with an intermediate skin color - mulattos (P1p1P2p2P3p3P4p4). If the spouses are mulattos, then the possible birth of children with skin pigmentation from the lightest to the darkest possible.

In typical cases, quantitative traits are inherited polygenically. Nevertheless, in nature there are examples of polygenic inheritance of qualitative traits, when final result does not depend on the number of dominant alleles in the genotype - the trait either manifests itself or does not manifest itself (noncumulative polymerization).

Pleiotropy- the ability of one gene to control several traits (multiple gene action). So, Marfan's syndrome in typical cases is characterized by a triad of signs: subluxation of the lens of the eye, heart defects, lengthening of the bones of the fingers and toes (arachnodactyly - spider fingers). This complex of traits is controlled by a single autosomal dominant gene, which causes abnormalities in the development of connective tissue.

3 hours (180 minutes) are allotted for the performance of the certification work in biology. The work consists of 3 parts, including 34 tasks.

Part 1 includes 24 tasks (A1 – A24). Each task is given 4 answer options, one of which is correct.

Part 2 contains 6 tasks (B1 – B6): 2 - with the choice of three correct answers out of six, 2 - for compliance, 2 - for establishing the sequence of biological processes, phenomena, objects.

Part 3 contains 4 tasks with a free answer (C1 – C4).

Complete tasks in the order in which they are given. If a task is troubling you, skip it. Return to the missed assignments if you have time.

For completing tasks of various complexity, from one to three points are given. The points received by you for completed tasks are summed up. Try to complete as many tasks as possible and score the most points.

We wish you success!

Part 1 (A)

A1. What science uses the twin research method?

2) genetics

3) selection

4) taxonomy

A2. Indicate the formulation of one of the provisions of the cell theory.

1) plant cells differ from animal cells by the presence of chloroplasts

2) a cell is a unit of structure, vital activity and development of organisms

3) prokaryotic cells do not have a formed nucleus

2) infusoria slipper

4) freshwater hydra

A5. Which genes are active in the first hybrid generation?

1) allelic

2) dominant

3) recessive

4) linked

A6. Mushroom in lichen

1) creates organic substances from inorganic

2) absorbs water and mineral salts

3) breaks down organic matter to mineral

4) communicates the lichen with the environment

A7. What is the complication of ferns compared to mosses?

1) in the process of photosynthesis, they form organic substances from inorganic

2) do not need water during fertilization

3) belong to higher spore plants

4) have roots and well-developed conductive tissues

A8. The body of protection in crayfish is:

2) abdominal legs

4) long antennae

A9. The secondary cavity has:

1) all chordates

2) only skullless

3) only cranial

4) chordates with less intensive metabolism

A10. Why is it important for a person to keep kidneys healthy?

1) undigested food is removed through them

2) through them liquid metabolic products are removed

3) digestive enzymes are formed in them

4) they regulate the content of hormones in the blood

A11. Why should food contain vitamins?

1) they are part of enzymes

2) they are part of hormones

4) they are keepers hereditary information

A12. A person in a state of intoxication poorly coordinates his actions, since his activity is disturbed

1) the autonomic nervous system

2) cerebellum

3) spinal cord

4) medulla oblongata

A13. Why is it dangerous to pet stray dogs?

1) you can catch baby pinworms

2) you can get infected with echinococcus

3) you can get infected with liver flukes

4) the Finns bovine tapeworm can enter the body

A14. That is structural unit kind?

2) colony

4) population

A15. What is the role of hereditary variability in evolution manifested?

1) in increasing the viability of the population

2) in increasing the genetic diversity of individuals in the population and increasing the efficiency of selection

3) in reducing the genetic diversity of individuals in the population and increasing the efficiency of selection

4) in an increase in the heterogeneity of individuals in the population and a decrease in the efficiency of selection

A16. What are the consequences of the action of motive selection?

1) preservation of old species

2) maintaining the reaction rate

3) the emergence of new species

4) elimination of individuals with new mutations

A17. What is the name of the factor that significantly deviates from the optimal value for the type?

1) abiotic

2) biotic

3) anthropogenic

4) limiting

A18. Why is the agroecosystem not characterized by a balanced cycle of substances?

1) it includes a small variety of species

2) it is characterized by a wide variety of species

3) it has long power chains

4) the abundance of a small number of species in it is high

A19. What process contributes to the repeated use of the same plants by plants chemical elements absorbed from the soil?

1) root pressure

2) photosynthesis

3) self-regulation

4) circulation of substances

A20. Energy exchange cannot go without plastic, since plastic exchange supplies energy

1) energy-rich ATP molecules

2) enzymes to speed up reactions

3) oxygen for cleavage reactions

4) inorganic salts and acid

A21. The opening of the centers of diversity and origin of cultivated plants served as the basis for the creation

1) Main Botanical Garden

3) breeding stations

4) Institute of Genetics

A22. To the highest nervous activity include:

1) mental, speech activity and memory

2) a group of orienting reflexes

3) instincts

4) reflexes that provide organic needs

A23. The material for evolutionary processes is:

1) genetic diversity of the population

3) acquired characteristics

4) useless or harmful signs

A24. The main role in the transformation of the biosphere is played by

1) living organisms

2) chemical processes

3) physical processes

4) mechanical phenomena

Part 2 (B)

IN 1. For prokaryotic organisms, in contrast to prenuclear life forms, the following signs are characteristic:

1) circular DNA is concentrated in the central part of the cell, not separated by the nuclear envelope from the rest of the cell;

3) chromosomes, mitochondria and plastids are absent;

4) cells are not characterized by mitosis;

5) have a very limited number of enzymes, use the host's metabolism;

AT 2. Charles Darwin's evolutionary ideas were manifested in the following views:

1) each species is capable of unlimited reproduction;

2) the driving forces of evolution are innate abilities for self-improvement and appropriate response to environmental conditions;

3) the "ladder of beings" is a reflection of the process of development from lower to higher forms;

4) those organisms that are better adapted to environmental conditions survive in the struggle for existence;

5) the limited life resources impede the realization of the potential for the reproduction of organisms;

6) the unit of evolution is a separate organism.

AT 3. Establish a correspondence between the characteristics of vitamins and hormones.

AT 4. Establish a correspondence between the trait of animals and the class for which this trait is characteristic:

AT 5. Establish the sequence of events that occur during mitotic cell division:

A) chromosomes concentrate at the poles of the cell and despiralize

B) chromosomes become denser, shortened

C) division of centromeres of all chromosomes occurs

D) a shell of the nuclei of daughter cells is formed around the chromosomes

D) chromosomes line up in the equatorial plane

AT 6. Establish a sequence of processes causing ecosystem changes.

A) settlement of the territory with mosses and bushy lichens

B) the appearance of shrubs and semi-shrubs

C) the formation of a herbal community

D) the appearance of scale lichens on rocks

E) the formation of a forest community

Part 3 (C)

C1. Why is it necessary to find out the number of small pond snails living in the rivers adjacent to them before grazing livestock on flooded meadows?

C2. What is the role of bacteria in nature? Give at least 4 values.

C3. What factors prevent the intensive growth of the number of organisms on the planet?

C4. The disease of hemophilia in dogs (as in humans) is caused by the linkage of the gene for blood clotting to the X chromosome (Xh). When crossing a short-legged female with normal blood and a male with long legs and normal blood clotting (long-legged is a recessive autosomal sign), one of the puppies turned out to be hemophilic with long legs. Make a scheme for solving the problem. Determine the genotypes of parents and offspring with normal blood clotting and short legs, gender and genotype of a hemophilic puppy with long legs.

Job No.	Answer	Job No.	Answer

Job No.	Answer

Job No.

Job No.

Job No.	Answer

Job No.	Answer


Response elements: 1) the small pond snail is the intermediate host of the hepatic fluke; 2) when its abundance is high, during the flooding of rivers, fluke cysts appear on the meadow plants, which will lead to infection of livestock.

The answer includes 1 of the above answer elements OR the answer includes 2 of the above elements, but contains non-gross biological errors
Wrong answer
Maximum score

(other formulations are allowed that do not distort its meaning)
Response elements: 1) bacteria - destroyers of organic substances, form humus, mineralize organic substances and complete the circulation of substances in nature; 2) bacteria are involved in the formation of minerals: oil, coal, peat, natural gas, sulfur, phosphorus; 3) bacteria-chemosynthetics and photosynthetics are involved in the formation organic matter; The answer includes 4-5 of the above elements, does not contain biological errors
The answer includes 3 of the above elements and does not contain biological errors, OR the answer includes 4-5 of the above elements, but contains non-gross biological errors
The answer includes at least 2 of the above elements and does not contain biological errors, OR the answer includes 3 of the above elements, but contains non-gross biological errors
Wrong answer
Maximum score

(other formulations are allowed that do not distort its meaning)
Response elements: 1) limited food resources; 2) limited habitat; 3) the influence of unfavorable factors (climatic, anthropogenic, biotic, etc.)
The answer includes all of the above elements, does not contain biological errors


Wrong answer
Maximum score

(other formulations are allowed that do not distort its meaning)
Response elements: 1) genotypes of parents: ♂ aaXHY (gametes aXH, aY); ♀ AaXHXh (gametes: AXH, aXH, AXh, aXh); 2) genotypes of puppies with normal blood clotting and short legs: AaXHXH, AaXHXh, AaXHY; 3) genotype of a hemophilic puppy with long legs: aaXhY (male). Other genetic symbols are allowed.
The answer includes all of the above elements, does not contain biological errors
The answer includes 2 of the above elements and does not contain biological errors, OR the answer includes 3 of the above elements, but contains non-gross biological errors
The answer includes 1 of the above elements and does not contain biological errors, OR the answer includes 2 of the above elements, but contains non-gross biological errors
Wrong answer
Maximum score

What do they mean when they talk about dominant and recessive inheritance?

Let's return to the fact that genes in the body are represented in pairs (alleles), and the manifestation of an external sign or disease determined by a particular gene depends on the combination of a pair of gene alleles obtained from the father and mother.

When both alleles in a pair are exactly the same (for example, OO, AA), then such a genotype and its owner are called homozygous, and when these alleles are different (say, AO) - heterozygous. It is known that if the homozygous OO and AA genotypes predetermine the first and second blood groups, respectively, then the owners of the heterozygous AO genotype will also have the second blood group. This means that in such a combination the effect of gene A is manifested and the effect of gene O is not manifested, that is, gene A dominates, and gene O is recessive in relation to it (the word "recessive" means disappearing). Thus, dominant genes manifest their action in both homozygous and heterozygous states, and recessive genes can manifest themselves only in a homozygous state and do not give external manifestations in heterozygous people.

Every science creates its own terminology and its own specific vocabulary, which is sometimes difficult to understand for the uninitiated. There is a semi-joke story about a serious physicist who independently and with great enthusiasm began to study genetics from the most serious sources. As a result, he memorized as a magic spell one mind-blowing phrase, which he liked to shock his acquaintances with: "The genotype manifests itself in the phenotype when the recessive allele is in a homozygous state."

The meaning of this tricky rule is that it is not always possible to determine the genotype of their owner by external signs. If we can say for certain about any person with the first blood group that he has a homozygous OO genotype, then such a definite conclusion cannot be drawn about people with the second blood group, since they can be either homozygous AA or heterozygous AO. In order to determine the genotype for the second blood group, additional information is needed about the relatives: father and mother, brothers and sisters, children, but not always, and they help to come to an unambiguous conclusion.

If we move from blood groups to problems of inheritance of diseases that are more important for future parents, then the principle of dominance and recessiveness is crucial for the nature of the family manifestation of the disease. Depending on whether the pathological gene is dominant or recessive in relation to its normal variant, it manifests itself in families in completely different ways. Therefore, there are dominant and recessive diseases.

What diseases are passed from generation to generation?

The dominant type of inheritance is outwardly the simplest and most obvious precisely because it is the dominant diseases that are transmitted from parents to children in several subsequent generations. Theoretically, dominant diseases can manifest themselves in heterozygous and homozygous (with respect to the pathological gene) people, but in life, as a rule, patients are still heterozygous. There are more of them, and most of these diseases usually occur in only one of the spouses. And this, in turn, contributes to the inheritance of a pathological gene also in a heterozygous state.

So, if a sick parent has one altered and one normal allele, then in families where one of the parents is sick, the altered gene (hence the disease itself) will be transmitted only in 50% of cases of childbirth, that is, half of them will be sick, and half are healthy. Sick children can also pass on a dominant disease to half of their offspring in the next generation, which creates a continuous chain of inheritance. Healthy children of sick parents who have not inherited the pathological gene cannot be a source of transmission of the disease to subsequent generations, and therefore, all their direct descendants will be healthy.

Men and women are equally susceptible to these diseases and also transmit them equally to their sons and daughters. More than 1000 diseases are now known to be inherited in a dominant manner. These include some forms of dwarfism, glaucoma - the main cause of blindness, familial hypercholesterolemia ( high level cholesterol in the blood, leading to cardiovascular disease), and many others.

Why do healthy parents have sick children?

Most of the traits and diseases inherited in a recessive manner also appear with the same frequency in men and women, but this is where the similarity with dominant inheritance ends. In the overwhelming majority of cases, in patients with recessive diseases, both parents are healthy, but they are heterozygous carriers of the same pathological gene. Inheritance (recessive) occurs when a child receives this altered gene from both parents. So the pathological gene passes from a heterozygous state to a homozygous one, which contributes to the manifestation of the disease as such.

In marriages of two heterozygous parents, each of whom transmits a normal gene to half of their children and an altered gene to half of their children, the proportion of offspring who will receive a "double dose" of the altered gene will be only a quarter, or 25%. Another 25% of children, on the contrary, will be homozygous for the normal gene obtained simultaneously from the father and mother, that is, they will be healthy. In the remaining 50% of cases, a normal gene will be inherited from one of the parents, and a pathological gene from the other, while the children will be healthy, since recessive signs do not appear in the heterozygous state.

Thus, with recessive inheritance, the proportion of healthy children is 75% (or 3/4), and the ratio of healthy and sick offspring is 3: 1 (the classic Mendelian ratio for recessive traits).

If patients survive to childbearing age and are able to leave offspring (which is observed much less often in recessive diseases than in dominant diseases), then they will necessarily pass on the pathological gene to their children, but this is still not enough for the child to inherit the disease itself. Because since it comes about fairly rare diseases, the chances that the second parent will also be the carrier of this particular gene are extremely low. Indeed, the children of patients are almost always healthy, although they are necessarily heterozygous carriers of the disease gene.

Therefore, another difference between recessive diseases and dominant diseases is that they usually manifest themselves in only one generation in siblings. In total, more than 800 recessively inherited diseases are known. Among them, such as the inability to assimilate milk sugar and other metabolic disorders, some forms of severe mental retardation, blood diseases.

If, with recessive inheritance, one fourth of the children are born sick, and three quarters of the children are healthy, then why were three sick children born in the same family and not a single healthy one?

This question reflects one of the common misconceptions of people unfamiliar with the probabilistic nature of the manifestation of genetic patterns. All numerical ratios, discovered by Mendel on plant hybrids and completely fair for hereditary human diseases, characterize the average ratios for all such cases in general. In specific families, where the number of children is limited, there may be deviations from the average ratio in any direction.

Since the transfer of one of the two genes from parents to children is random, that is, to a certain extent, similar to a lottery, the genotype of each subsequent child in no way depends on the genotype of the previous one, and each time the lottery is held according to the same rules. Recall that when a coin is tossed, heads and tails are thrown equally often, but not strictly alternately. Therefore, the principle "probability has no memory" fully applies to the manifestations of hereditary diseases in families.

This means that the birth of one or more sick children does not guarantee a certain married couple of compulsory compensation in the future. Based on the probabilistic nature of the laws of inheritance genetic diseases, for each subsequent child, the risk of being born ill is strictly constant, as is the probability of being born healthy (provided that the type of inheritance of a particular disease and the genotypes of the parents are firmly established).

Why are consanguineous marriages dangerous and harmful?

Marriages between close relatives have long been considered undesirable and in many countries are prohibited by law and social customs. This is known, but even between father and daughter or sibling and sibling, incestuous relationships are much more common than commonly believed. Marriages between uncle and niece, cousins or second cousins are quite frequent, although they are subject to social and religious restrictions in Europe, North America and other regions with Christian traditions, and in many traditionally Muslim Asian populations, they are generally preferred. In our country, these traditions still make themselves felt in the republics Central Asia and Azerbaijan.

What is the genetic danger of such marriages? If we remember that recessive diseases are manifested in families where both parents are carriers of the same harmful gene, this danger becomes clearer. The fact is that most of the known recessive diseases are quite rare, and an accidental coincidence in the carriage of the same genetic defect in both spouses is also a rare event. But if relatives marry, then the likelihood of such a coincidence increases dramatically.

The explanation is quite simple. After all, blood relatives are relatives who have at least one, more often two, and sometimes more common ancestors. For example, a cousin and a sister have the same grandparents. And it was already mentioned above that each person is a carrier of at least one or two harmful recessive genes. Therefore, the pathological gene that the grandfather or grandmother had could well be passed on to both of their grandchildren, who, therefore, in this case, will be carriers of the same harmful gene obtained from a common source.

Therefore, children from such married couples are much more likely to have various recessive diseases, and pregnancies often end in spontaneous abortions and stillbirths than in unrelated marriages. On the other hand, in burdened families, a clear relationship was noted between the frequency of recessive diseases and consanguineous marriages: the less common the disease, the more often the parents of sick children turn out to be blood relatives. And one more dependence: the closer the degree of relationship between spouses, the higher the risk of genetic complications for their offspring.

Why does hemophilia (like color blindness) only affect men?

The peculiar nature of the inheritance of these diseases was noticed by people in ancient times. For example, the Talmud contains information about the danger of circumcision in those boys whose mothers had fathers or brothers with increased bleeding. In the language of modern genetics, if the transmission of a disease depends on sex, this type of inheritance is called sex-linked, or even more strictly, X-linked inheritance.

IN this case we are talking about a special kind of manifestation of recessive genes that are located on one of the sex chromosomes, namely the X chromosome. Women normally have two X chromosomes, while men have one X chromosome and one Y chromosome. Therefore, in women, all genes of the X chromosome are paired, as in all other chromosomes, and in men, unpaired, since the Y chromosome has no genes in common with the X chromosome.

Recessive harmful genes located on the X chromosome in women in a heterozygous state, naturally, do not manifest their pathological effect. In men, the effect of these genes can be manifested, although the pathological genes do not go into a homozygous state as in ordinary recessive inheritance, but are in a "single" dose (the so-called half genotype). These harmful genes manifest themselves because there are no normal genes corresponding to them in the Y chromosome, which would prevent the development of the disease.

The vast majority of X-linked diseases occur when the mother is a heterozygous carrier of an altered gene on one of the X chromosomes. At the same time, the mother does not have any manifestations of the disease, but each child can receive from her either a "sick" or "healthy" gene. It is known that either the X chromosome or the Y chromosome is inherited from the father, the girl will be born with the combination XX, and the boy with the combination XV. If a girl receives a "sick" gene from her mother, she will also become a carrier of the disease, since the second, a "healthy" gene received from her father, will not allow the disease to manifest itself. But if the "sick" gene gets to the future son, he will get sick.

The general criteria for the inheritance of sex-linked diseases are as follows:

transmission of the disease from fathers to sons is never observed, since the son never inherits the X chromosome from the father;
all daughters of a sick man must receive an altered gene and are carriers;
healthy men never transmit the disease to their offspring of either sex;
half of the sons of women who are carriers of the disease will be sick, and half will be healthy;
half of the daughters of women who are carriers of the disease will also be carriers.

It is known that there are no rules without exceptions. Although X-linked diseases are called sex-linked diseases, in principle, the appearance of sick women is possible. After all, theoretically, one can draw an analogy with simple recessive inheritance and come to the conclusion that women homozygous for the mutant gene will be sick in the same way as men, with a halved genotype. However, in practice, this is extremely rare. Therefore, the last criterion for X-linked inheritance is as follows: sick homozygous women with X-linked inheritance are an exception that is observed only when a sick man marries a carrier of the same disease.

In general, in rare diseases, such marriages almost never occur, but their likelihood, again, is higher with the consanguinity of the husband and wife. We have seen a real confirmation of this in studies carried out in one Azerbaijani village, where many patients with hemophilia have been identified for several generations. Most of them, of course, were men, but there were also three obviously sick women. They were all daughters of sick fathers who were married to their maternal relatives.

What is vertical, horizontal and knight move inheritance?

At graphic image pedigrees (genealogical trees) of families with diseases different types inheritance, you can notice the characteristic features.

So, in the case of typical dominant inheritance, it is possible to trace the direct transmission of the disease from parents to children over several generations. This nature of family accumulation is commonly called vertical inheritance.

In the case of a typical recessive inheritance that does not depend on gender, the disease is most often traced only in one generation - in siblings. This is horizontal inheritance.

Finally, the most intricate pattern is found in X-linked pedigrees. In a straight downward (in generations) line, sick men and their healthy daughters, granddaughters, who, however, are carriers of a pathological gene and, as a result, have sick sons, can alternate.

In other words, in a straight downward line between two sick men, there must necessarily be one or more intermediate generations of healthy women. However, some of these healthy carriers in intermediate generations have sick brothers (relatives, cousins) belonging to the lateral descending branches family tree... That is why if sick men of different generations are linked in a pedigree, then inheritance by the "move of a chess knight" is obtained.

Test on the topic "Genetics"

A1. In fruit fly Drosophila in somatic cells contains 8 chromosomes, and in the germ cells -

1) 12 2) 10 3) 8 4) 4+

A2. Paired genes of homologous chromosomes are called

1) allelic + 2) linked

3) recessive 4) dominant

A3. What law will manifest itself in the inheritance of traits when crossing organisms with genotypes: Aa x Aa?

1) uniformity 2) splitting +

3) linked inheritance 4) independent inheritance

A4. What is the ratio of traits by phenotype observed in the offspring during the analyzing crossing, if the genotype of one of the parents is AaBb (traits are inherited independently of each other)?

1) 1:1 2) 3:1 3) 1:2:1 4) 1:1:1:1 +

A5. What are the names of individuals that form one variety of gametes and do not give splitting traits in the offspring?

1) mutant 2) heterotic

3) heterozygous 4) homozygous +

A6. How are the genotypes of individuals designated during dihybrid crossing?

1) BbBb × AaAa 2) AaBb × AaBb +

3) AaAA × BbBb 4) AAaa × BBbb

A7. All leaves of the same plant have the same genotype, but may differ in

1) the number of chromosomes 2) phenotype +

3) gene pool 4) genetic code

A8. With dihybrid crossing and independent inheritance of traits in parents with genotypes AABb and aabb, a splitting is observed in the offspring in the ratio

1) 9:3:3:1 2) 1:1:1:1 3) 3:1 4) 1:1 +

A9. The method of studying human heredity, which is based on the study of the number of chromosomes, the features of their structure, is called 1) genealogical 2) twin 3) hybridological 4) cytogenetic +

A10. How many gamete species are formed in diheterozygous pea plants during dihybrid crossing (genes do not form a linkage group)? 1) one 2) two 3) three 4) four

A11. When two guinea pigs with black wool were crossed (dominant trait), offspring were obtained, among which individuals with white wool accounted for 25%. What are the genotypes of the parents? 1) AA x aa; 2) Aa x AA; 3) Aa x Aa; + 4) AA x AA.

A12. The number of linkage groups of genes in organisms depends on the number

1) pairs of homologous chromosomes + 2) allelic genes

3) dominant genes 4) DNA molecules in the cell nucleus

A13. Pure plant line is offspring

1) heterotic forms 2) one self-pollinating individual +

3) intervarietal hybrid 3) two heterozygous individuals

A14. In dogs, black coat (A) dominates over brown (a), and short-legged (B) over normal leg length (b). Select the genotype of a black short-legged dog, heterozygous only for the length of the legs.

1) ААBb + 2) Аabb 3) AaBb 4) AABB

A15. Chromatids are

1) two subunits of the dividing cell chromosome +

2) sections of the chromosome in a non-dividing cell

3) circular DNA molecules

4) two chains of one DNA molecule

A16. In breeding for obtaining new polyploid plant varieties

1) breed individuals of two pure lines

2) interbreed parents with their offspring

3) multiply the set of chromosomes +

4) increase the number of homozygous individuals

A17. What percentage of pink flowered night beauty plants can be expected from red and white flowered crosses (incomplete dominance)?

1) 25% 2) 50% + 3) 75% 4) 100%

A18. The set of chromosomes in human somatic cells is

1) 48 2) 46+ 3) 44 4) 23

A19. What method was used to study human chromosomal disease - Down syndrome?

1) genealogical 2) twin

3) cytogenetic + 4) biochemical

A20. Albinism is defined by a recessive autosomal gene, and hemophilia is defined by a recessive sex-linked gene. Indicate the genotype of the albino woman, hemophiliac.

1) AaX H Y or AAX H Y 2) AaX H NS H or AA X H NS H

3) aaX h Y 4) aaX h X h +

A21. Which genes are active in the first hybrid generation?

1) allelic 2) dominant + 3) recessive 4) linked

A22. When crossing dominant and recessive individuals, the first hybrid
generation is uniform. How can this be explained?

1) all individuals have the same genotype +

2) all individuals have the same phenotype

3) all individuals are similar to one of the parents

4) all individuals live in the same conditions

A23. When tomatoes were crossed with red and yellow fruits, offspring were obtained, in which half of the fruits were red and half were yellow. What are the genotypes of the parents?

1) AA x aa 2) Aa x AA 3) AA x AA 4) Aa x aa +

A24. What is the name of the method, the essence of which is the crossing of parental forms that differ in a number of characteristics, the analysis of their manifestation in a number of generations?

1) hybridological + 2) cytogenetic

3) twin 4) biochemical

A25. From hybrids of the first generation in the second generation, 1/4 of individuals with recessive traits are born, which indicates the manifestation of the law

1) linked inheritance 2) splitting +

3) independent inheritance 4) intermediate inheritance

A26. What is the function of the chromosome in the cell?

1) photosynthesis 2) protein biosynthesis

3) phagocytosis 4) carrier of hereditary information +

A27. What method is used to identify the influence of genotype and environment on child development?

1) genealogical 2) twin +

3) cytogenetic 4) hybridological

A28. The birth from hybrids of the first generation in the second generation of half of the offspring with an intermediate trait indicates the manifestation

1) linked inheritance 2) independent inheritance

3) gender-related inheritance 4) incomplete dominance +

A29. The reason for the splitting of individuals with dominant traits in F 2, obtained from hybrids of the first generation, is their

1) hereditary heterogeneity + 2) a wide reaction rate

3) narrow reaction rate 4) genetic uniformity

A30.The essence of the hybridological method is

1) crossing organisms and analyzing offspring +

2) determining the genotype of the parents

3) researching the family tree

4) receiving modifications.

A31. Scheme AABB x aabb illustrates crossbreeding

1) monohybrid 2) polyhybrid

3) analyzing dihybrid + 4) analyzing monohybrid

A32. An organism whose genotype contains different alleles of the same gene is called

1) recessive 2) dominant

3) heterozygous + 4) homozygous

A33. How did G. Mendel call the signs that are not manifested in the first generation hybrids?

1) heterozygous 2) homozygous

3) recessive + 4) dominant

A34. The set of genes that the body receives from its parents is called

gene pool 2) heredity 3) phenotype 4) genotype +

A35. In a cell, a pair of allelic genes is located on the chromosomes

1) non-homologous 2) paternal 3) maternal 4) homologous +

A36. Indicate the genotype of a person, if by phenotype he is fair-haired and blue-eyed (recessive traits).

1) AABB 2) AaBb 3) aabb + 4) Aabb

A37. Hybrid individuals are heterogeneous by their genetic nature and form gametes of different varieties, therefore they are called

heterozygous + 2) homozygous 3) recessive 4) dominant

A38. Individuals that form one variety of gametes and do not give splitting of characters in the offspring,

mutant 2) heterotic 3) heterozygous 4) homozygous +

A39. The child, like his parents, has 46 chromosomes, of which

44 paternal and 2 maternal

45 maternal and one paternal Y chromosome

23 maternal and 23 paternal +

44 maternal and 2 paternal

A40. A girl develops from an egg if chromosomes are found in the zygote during fertilization

1) 44 autosomes + XY 2) 23 autosomes + X

3) 44 autosomes + XX + 4) 23 autosomes + Y

A41.New combinations of parental genes in the zygote cause

cytoplasmic inheritance

somatic mutations

combinative variability +

DNA nucleotide abnormalities

A42. What gametes are formed in an individual with the Aabb genotype?
1) Ab, bb 2) Ab, ab + 3) Aa, AA 4) Aa, bb

A43. The presence in a gamete of one gene from each pair of alleles is a cytological basis

chromosome theory heredity

linked inheritance law

independent inheritance law

gamete purity hypothesis

A44. How are the genotypes of individuals designated during dihybrid crossing?

1) Bbb x AaAa 2) AaAA x Bbb

3) AaBb x AaBb + 4) Aaaa x Bbb

A45. As a result of what process is the genotype of the offspring formed?

ontogenesis 2) ovogenesis

3) spermatogenesis 4) fertilization +

A46. Determine the genotype of an individual of a yellow curly pumpkin, if during its self-pollination in F1, the splitting of traits by phenotype corresponded to 9: 3: 3: 1

1) AABB 2) AaBB 3) AaBb + 4) AABB

A47. In self-pollination of a heterozygous tall pea plant (high stem -A), the proportion of dwarf forms is

1) 25% + 2)50%3)75% 4) 0%

A48. What phenotype can be expected in the offspring of two white-coated guinea pigs (recessive trait)?

100% white +

25% white and 75% black

50% white and 50% black

75% white and 25% black

A49. What part of individuals with a recessive trait will appear in the first generation when two parents heterozygous for this trait are crossed?

1)75%2)50%3)25% +4)0%

A50. Determine the genotypes of parents with brown eyes, if their offspring have three brown-eyed and one blue-eyed child (A - brown eyes dominate over blue).

1) aa x AA 2) AA x Aa 3) AA x AA 4) Aa x Aa +

A51. If, with monohybrid crossing in the second generation of hybrids, a splitting according to the phenotype 1: 2: 1 is observed, then this is a consequence

incomplete dominance + 2) complete dominance

3) gene interactions 4) linked inheritance

A52. Continuity in the structure and life of organisms in a number of generations is ensured

variability 2) fitness 3) self-regulation 4) heredity +

A53. The gene for color blindness is recessive, sex-linked. Indicate the genotype of a man with normal color vision.

l) X d X d 2) X D X d 3) X d Y 4) X D Y +

A54. When crossing a black rabbit (Aa) with a black rabbit (Aa) in generation F 1, rabbits will be obtained

100% black 2) 75% black, 25% white +

3) 50% black, 50% white 4) 25% black, 75% white

A55. Determine the genotype of the parent pea plants, if 50% of plants with yellow seeds and 50% with green seeds were formed during their crossing (recessive trait)

1) AAhaa 2) Aa x Aa 3) AAxAa 4) Aa x aa +

A56. What is the probability of birth of tall children in heterozygous parents with short stature (short stature dominates over high stature)?

1) 0% 2) 25% + 3) 50% 4) 75%

A57. If the ratio of genotypes and phenotypes as a result of monohybrid crossing is 1: 2: 1, then the original parental individuals

homozygous. 3) dihomozygous 2) heterozygous + 4) diheterozygous

A58. When crossing homozygous tomato plants with red (A) round (B) fruits and plants with yellow (a) pear-shaped (b) fruits in F 2, phenotype splitting occurs in the ratio (genes for color and shape of fruits are located in different pairs of chromosomes)

1) 1: 1 2)3: 1 3) 1: 2: 1 4) 9: 3: 3: 1 +

A59. When drosophila flies with long and short wings were crossed, an equal number of long-winged and short-winged offspring was obtained (long wings B dominate over short ones b). What are the genotypes of the parents?

l) bb x Bb + 2) BBxbb 3) BbxBb 4) BBxBB

A60. When crossing homozygous pea plants with yellow round seeds and green wrinkled seeds (A - yellow, B - round) in F 2, the ratio of individuals with different phenotypes, equal to 9: 3: 3: 1, indicates the manifestation of the law

dominance 2) linked inheritance

3) splitting + 4) intermediate inheritance

A61. When drosophila flies are crossed with a gray body and normal wings with a dark body and rudimentary wings, the law of linked inheritance appears, since the genes are located in

different chromosomes and linked 2) one chromosome and linked +

3) one chromosome and not linked 4) different chromosomes and not linked

A62. When crossing heterozygous pea plants with yellow smooth seeds with green (a) wrinkled (b) seeds, the number of phenotypes in the offspring will be equal to

1) one 2) two 3) three 4) four +

A63. When heterozygous tomato plants with red and round fruits are crossed with individuals recessive in both traits (red A and round B are dominant characters), offspring with genotypes AaBb, aaBb, Aabb, aabb will appear in the ratio

1)3:12)9:3:3:13)1:1:1:1 + 4)1:2:1

A64. Human eye color is determined by an autosomal gene, and color blindness is determined by a recessive sex-linked gene. Determine the genotype of a brown-eyed woman with normal color vision, father
which is color blind (brown-eyed dominates over blue-eyed).

1) AAX B X B 2) AaX b X b 3) AaX B X b + 4) aaX B X b

A65. What percentage of individuals of the roan suit can be obtained when crossing red (BB) and white (bb) cattle with incomplete dominance?

1) 25%2) 50% + 3) 75%4) 100%

A66. As a result of crossing the plants of the night beauty with white and red flowers, they got offspring with pink flowers, since it is observed

multiple action of genes 2) intermediate inheritance +

3) the phenomenon of complete domination 4) linked inheritance of traits

A67. If the genes responsible for the development of several traits are located on the same chromosome, then the law manifests itself

splitting 2) linked inheritance +

3) incomplete dominance 4) independent inheritance

A68. When rabbits were crossed with shaggy and smooth hair, all rabbits in the offspring had shaggy hair. What pattern of inheritance manifested itself in this case?

independent distribution of features 2) incomplete dominance

3) uniformity of the first generation + 4) splitting of signs

A69. With dihybrid crossing and independent inheritance of traits in parents with genotypes AABb and aabb, a splitting is observed in the offspring in the ratio

1) 9:3:3:12) 1:1:1:13) 3:14) 1:1 +

A70. Determine the ratio of phenotypes in hybrids of the first generation when crossing two heterozygous plants of garden strawberries (Aa-pink fruit color, intermediate inheritance)

100% pink fruits

50% pink: 50% red

25% red: 25% pink: 50% white

25%) red: 50% pink: 25% white +

A71. Hemophilia in children is more often manifested from marriage -

unrelated 2) closely related +

3) people of different nationalities 4) people of different races

A72. A woman with light (a) straight (b) hair married a man with dark curly hair (incomplete dominance). Determine the genotype of a man if their child has blonde and wavy hair.

1) AaBb 2) aaBb 3) AABB 4) AaBB +

A73. Albinism is determined by a recessive autosomal gene, and hemophilia is determined by a recessive sex-linked gene, indicate the genotype of an albino woman, hemophilic.

1) AaX N U or AAXH N U 2) AaH N X N or AAX N X N

3) aaH h Y 4) aaX h X h +

A74. How many gamete types are formed in a heterozygous bull with a black coat (black dominates over red)?

1) one 2) two + 3) three 4) four

C1. How are heterozygotes different from homozygotes?

They form different gametes carrying different genes of a given pair.

C2. In humans, the gene for brown eyes (A) dominates over blue eyes, and the gene for color blindness is recessive (color blindness - d) and linked to the X chromosome. A brown-eyed woman with normal vision, whose father had blue eyes and suffered from color blindness, marries a blue-eyed man with normal vision. Make a scheme for solving the problem. Determine the genotypes of the parents and possible offspring, the likelihood of birth in this family of color-blind children with brown eyes and their gender.

C3. By crossing a tomato with a purple stem (A) and red fruits (B) and a tomato with a green stem and red fruits, 722 plants with a purple stem and red fruits and 231 plants with a purple stem and yellow fruits were obtained. Make a scheme for solving the problem. Determine the genotypes of the parents, offspring in the first generation and the ratio of genotypes and phenotypes in the offspring.

GAU DPO (PC) S "Bryansk regional center assessing the quality of education "

Demo version of the test in 2011-2012 academic year proposed to establish the correspondence of the qualification level (first and highest)

Biology

Bryansk

Work instructions

3 hours (180 minutes) are allotted for the performance of the certification work in biology. The work consists of 3 parts, including 34 tasks.

Part 1 includes 24 tasks (A1-A24). Each task is given 4 answer options, one of which is correct.

Part 2 contains 6 tasks (B1-B6): 2 - with the choice of three correct answers out of six, 2 - for compliance, 2 - for establishing the sequence of biological processes, phenomena, objects.

Part 3 contains 4 tasks with a free answer (C1-C4).

Complete tasks in the order in which they are given. If a task is troubling you, skip it. Return to the missed assignments if you have time.

We wish you success!

Part 1 (A)

A1. What science uses the twin research method?

1) cytology

2) genetics

3) selection

4) taxonomy

A2. Indicate the formulation of one of the provisions of the cell theory.

1) plant cells differ from animal cells by the presence of chloroplasts

2) a cell is a unit of structure, vital activity and development of organisms

3) prokaryotic cells do not have a formed nucleus

4) viruses do not have a cellular structure

A3. Which virus disrupts the human immune system?

1) poliomyelitis

A4. Define an organism in which cell differentiation occurs in the process of ontogenesis?

1) common amoeba

2) infusoria slipper

3) multicellular alga

4) freshwater hydra

A5. Which genes are active in the first hybrid generation?

1) allelic

2) dominant

3) recessive

4) linked

A6. Mushroom in lichen

1) creates organic substances from inorganic

2) absorbs water and mineral salts

3) breaks down organic matter to mineral

4) communicates the lichen with the environment

A7. What is the complication of ferns compared to mosses?

1) in the process of photosynthesis, they form organic substances from inorganic

2) do not need water during fertilization

3) belong to higher spore plants

4) have roots and well-developed conductive tissues

A8. The body of protection in crayfish is:

2) abdominal legs

4) long antennae

A9. The secondary cavity has:

1) all chordates

2) only skullless

3) only cranial

4) chordates with less intensive metabolism

A10. Why is it important for a person to keep kidneys healthy?

1) undigested food is removed through them

2) through them liquid metabolic products are removed

3) digestive enzymes are formed in them

4) they regulate the content of hormones in the blood

A11. Why should food contain vitamins?

1) they are part of enzymes

2) they are part of hormones

4) they are custodians of hereditary information

A12. A person in a state of intoxication poorly coordinates his actions, since his activity is disturbed

1) the autonomic nervous system

2) cerebellum

3) spinal cord

4) medulla oblongata

A13. Why is it dangerous to pet stray dogs?

1) you can catch baby pinworms

2) you can get infected with echinococcus

3) you can get infected with liver flukes

4) the Finns bovine tapeworm can enter the body

A14. What is the structural unit of a species?

2) colony

4) population

A15. What is the role of hereditary variability in evolution manifested?

1) in increasing the viability of the population

2) in increasing the genetic diversity of individuals in the population and increasing the efficiency of selection

3) in reducing the genetic diversity of individuals in the population and increasing the efficiency of selection

4) in an increase in the heterogeneity of individuals in the population and a decrease in the efficiency of selection

A16. What are the consequences of the action of motive selection?

1) preservation of old species

2) maintaining the reaction rate

3) the emergence of new species

4) elimination of individuals with new mutations

A17. What is the name of the factor that significantly deviates from the optimal value for the type?

1) abiotic

2) biotic

3) anthropogenic

4) limiting

A18. Why is the agroecosystem not characterized by a balanced cycle of substances?

1) it includes a small variety of species

2) it is characterized by a wide variety of species

3) it has long power chains

4) the abundance of a small number of species in it is high

A19. What process contributes to the repeated use by plants of the same chemical elements absorbed from the soil?

1) root pressure

2) photosynthesis

3) self-regulation

4) circulation of substances

A20. Energy exchange cannot proceed without plastic, since plastic exchange supplies energy

1) energy-rich ATP molecules

2) enzymes to speed up reactions

3) oxygen for cleavage reactions

4) inorganic salts and acids

A21. The discovery of N.I. Vavilov centers of diversity and origin of cultivated plants served as the basis for the creation

1) Main Botanical Garden

2) collections of seeds of plant species and varieties

3) breeding stations

4) Institute of Genetics

A22. Higher nervous activity includes:

1) thinking, speech activity and memory

2) a group of orienting reflexes

3) instincts

4) reflexes that provide organic needs

A23. The material for evolutionary processes is:

1) genetic diversity of the population

3) acquired characteristics

4) useless or harmful signs

A24. The main role in the transformation of the biosphere is played by

1) living organisms

2) chemical processes

3) physical processes

4) mechanical phenomena

Part 2 (B)

IN 1. For prokaryotic organisms, in contrast to prenuclear life forms, the following signs are characteristic:

1) circular DNA is concentrated in the central part of the cell, not separated by the nuclear envelope from the rest of the cell;

3) chromosomes, mitochondria and plastids are absent;

4) cells are not characterized by mitosis;

5) have a very limited number of enzymes, use the host's metabolism;

AT 2. Charles Darwin's evolutionary ideas were manifested in the following views:

1) each species is capable of unlimited reproduction;

2) the driving forces of evolution are innate abilities for self-improvement and appropriate response to environmental conditions;

3) the "ladder of beings" is a reflection of the process of development from lower to higher forms;

4) those organisms that are better adapted to environmental conditions survive in the struggle for existence;

5) the limited life resources impede the realization of the potential for the reproduction of organisms;

6) the unit of evolution is a separate organism.

AT 3. Establish a correspondence between the characteristics of vitamins and hormones.

AT 6. Establish a sequence of processes causing ecosystem changes.

A) settlement of the territory with mosses and bushy lichens

B) the appearance of shrubs and semi-shrubs

C) the formation of a herbal community

D) the appearance of scale lichens on rocks

E) the formation of a forest community

Part 3 (C)

C1. Why is it necessary to find out the number of small pond snails living in the rivers adjacent to them before grazing livestock on flooded meadows?

C2. What is the role of bacteria in nature? Give at least 4 values.

C3. What factors prevent the intensive growth of the number of organisms on the planet?

C4. The disease of hemophilia in dogs (as in humans) is caused by the linkage of the gene for blood clotting to the X chromosome (X h). When crossing a short-legged female with normal blood and a male with long legs and normal blood clotting (long-legged is a recessive autosomal sign), one of the puppies turned out to be hemophilic with long legs. Make a scheme for solving the problem. Determine the genotypes of parents and offspring with normal blood clotting and short legs, gender and genotype of a hemophilic puppy with long legs.

Job No.	Answer	Job No.	Answer

Job No.	Answer

Job No.

Job No.

Job No.	Answer

Job No.	Answer


Response elements: 1) bacteria - destroyers of organic substances, form humus, mineralize organic substances and complete the circulation of substances in nature; 2) bacteria are involved in the formation of minerals: oil, coal, peat, natural gas, sulfur, phosphorus; 3) bacteria-chemosynthetics and photosynthetics are involved in the formation of organic matter; 4) nitrogen-fixing bacteria improve nitrogen nutrition of plants; The answer includes 4-5 of the above elements, does not contain biological errors
The answer includes 3 of the above elements and does not contain biological errors, OR the answer includes 4-5 of the above elements, but contains non-gross biological errors
The answer includes at least 2 of the above elements and does not contain biological errors, OR the answer includes 3 of the above elements, but contains non-gross biological errors
Wrong answer
Maximum score

(other formulations are allowed that do not distort its meaning)
Response elements: 1) limited food resources; 2) limited habitat; 3) the influence of unfavorable factors (climatic, anthropogenic, biotic, etc.)



Wrong answer
Maximum score

(other formulations are allowed that do not distort its meaning)
Response elements: 1) genotypes of parents: ♂ aaX H Y (gametes aX H, aY); ♀ AaX H X h (gametes: AX H, aX H, AX h, aX h); 2) genotypes of puppies with normal blood clotting, having short legs: AaX H X H, AaX H X h, AaX H Y; 3) the genotype of a hemophilic puppy with long legs: aaX h Y (male). Other genetic symbols are allowed.
The answer includes all of the above elements, does not contain biological errors
The answer includes 2 of the above elements and does not contain biological errors, OR the answer includes 3 of the above elements, but contains non-gross biological errors
The answer includes 1 of the above elements and does not contain biological errors, OR the answer includes 2 of the above elements, but contains non-gross biological errors
Wrong answer
Maximum score