Chapter 2

The genetic sciences

1. Who is known as the father of genetic science?

Gregor Johann Mendel  is known as the father of genetic science  . 

2. What is heredity?

Answer: Heredity is the passing on of genetic traits from parents to children. 

or

        Heredity is the process by which hereditary traits are passed on from one generation to the next.

3. From when did Mendel conduct his genetic research?

Mendel  conducted his genetic research from 1857 to 4. The Where did Mendel express his knowledge of research?

 Mendel published his research in the journal of the Natural History Society of Bonne  

5. Who rediscovered Mendel's formulas of heredity?

Mendel's formulas of heredity were rediscovered  by  Hugo da Vies of the Netherlands, von Cermak of Austria and Karl Korens of Germany  .

6. What is Mendel’s monohybrid ratio?

For the first experiment, Mendel crossed trees with two opposite traits of a type of character to determine the ratio in which the two opposite traits were obtained . This is called Mendel's hybrid ratio.

or

        Mendel first determined the ratio of two opposite traits by crossing two trees of the same character. This is the ratio of Mendel's hybrid.  

7. What is a gene?

Answer: Genes are tiny substances on chromosomes that control heredity. Genes are the carriers of heredity. 


8. What is Mendel’s dihybrid ratio?

Answer: Mendel's dihybrid ratio is 9 : 3 : 3

9. What is good reproductive science?

Answer: Good reproductive science is the science by which the welfare of mankind can be achieved by controlling and correcting the hereditary traits of future descendants of mankind through genetic decisions under the applied science of genetics. 


10. Who pioneered the science of good reproduction?

Answer:  The science of good reproduction was started in 1883 by Francis Galton. 11. 11. What are the other types of good reproductive science?

Answer:  There are two types of good reproduction science. They are 一 negative and positive. 

12. What is another name for Downs Syndrome?

Answer:  Another name for Downs syndrome is  Mongolian dementia.

13. Turners Syndrome What is the number of chromosomes in a woman?

Answer:  Turners syndrome The number of chromosomes in a woman's body is

14. What causes Klinefelter syndrome?

Klinefelter syndrome is caused by a disorder of the human sex chromosomes . 

15. Who first invented Klinefelter syndrome?

Answer:  Klinefelter syndrome   was first coined by Harry FitzKlinefelter .

16. Write a note about Downs syndrome?

Down's syndrome is caused by a triplet of chromosome This disease can affect both men and women. Patients with this disease have no fertility and the growth or development of the body is hampered everywhere. The palm and fingertip lines are not normal. The eyes are also different in size, meaning that the petals hang over the eyes. They are mentally disabled. Such people are more likely to develop leukemia. Such individuals are shorter in height and may have similar facial features. This trimerization is usually caused by non-disjunction events during cell division.


17. Write briefly:

(a) Tanner's syndrome

Answer:  Tanner's syndrome is more common in women. There is a missing X chromosome in the chromosome. It is of the XO type. Women with this disease are thin in appearance. They are usually sterile. It is a disorder caused by a sex chromosome abnormality. Such women look like men. Such women do not develop breasts. The shoulders are broad like men and the hips are stubby. They have a lot of hair on their bodies.


(b) Klinefelter syndrome

Klinefelter syndrome is caused   by a disorder of the sex chromosomes in humans. This disease is more common in men. Men with the disease have some female symptoms and men with the disease are infertile. The number of chromosomes is XXY or XXXY. Such a person does not have sperm. The bones are thin. Less facial and body hair. 

(c) Good reproductive science

Answer: Good reproduction science is a branch of applied genetic science in which the welfare of mankind can be achieved by controlling and correcting the hereditary traits of future descendants of human beings through genetic decisions. The science of good breeding was started in 1883 by Francis Galton.  It failed as a science in the 1930s and 1940s when 'Nazis' were killed in Germany as "socially inferior" and eugenics was misused. During World War I, many scientists  and politicians supported this well-breeding science.

            The real purpose of good breeding science is to change the genetic traits of an individual human being and to eliminate the good genetic traits by inheriting them and the bad traits by inheriting them.

            There are two types of concepts of good reproductive science 一 negative and positive. The main objective of positive breeding science is to continue breeding with good traits and the main objective of negative breeding science is to breed well by eliminating the symptoms of physical and mental disorders. Sterilization and isolation are also used. 

18. Describe Mendel’s monohybrid ratio with diagrams.

Answer:- 

19. Describe Mendel’s dihybrid ratio.

Answer:  In the one-hybrid experiment, Mendel based on only one symptom. Later, he took two or more types of symptoms together and found that there were different groups for different symptoms. Each group moves independently from one man to the next. He thereby reached another conclusion called the independent diversification formula. This formula is also known as the bi-hybrid ratio.

            Mendel chose pure tall trees with pure round seeds and pure arch trees with pure short seeds for his experiments. Four signs of two types of character were found. This gave the ratio of dihybrids.

            When fertilization was allowed between the two trees, the first generation trees were obtained in the ratio of 9 : 3 : 3 : 1 : ie 9 round tall : 3 short tall : 3 round arch : 1 round arch. Mendel's test of the double-hybrid ratio can be explained as follows. He named the effective rotation R and the ineffective shotora r, the effective tall T and vice versa the ineffective flat t. The pure round seed tree is RRTT and the pure shotra seed pressure tree is rrtt. The first type of RT and the second type of rt will produce gametes. So the trees of the first generation will be Rt Tr. Four types of reproductive cells are obtained from this hybrid plant. These four types of gametes are— RT, Rt, rT, rt.


Trees numbered 1, 2, 3, 4, 5, 7, 9, 10, 13 are round tall = 9

Trees number 11, 12, 15 are shorter height =

Trees 6, 8, 14 are round arc =

Tree number 16 is of short pressure = 

That is, the Mendel's dihybrid ratio is = 9 : 3 : 3 :

20. Write briefly:

(a) Genes and alleles

Answer:  Genes are tiny substances on chromosomes that control heredity. It is the carrier of heredity. Genes in an organism are paired. Genes at the same location are called alleles or alleomorphs. Pure tall trees found in Mendel's experiments have two TT genes. One of these TT genes is called an allele of the other. Similarly, one of the tt genes is an allele of the other. There are 46 chromosomes in the human body.

(b) genotype and phenotype

Answer:  A genotype is the set of all the genes of an organism. TT, tt and tt genotypes. Genotype is the type of division based on the presence of a gene. The 1:2:1 ratio of Mendel's hybrid test is based on genotype.

        A phenotype is the set of characters expressed in an organism. A phenotype is the appearance of an organism. The 3:1 ratio resulting from Mendel's monohybrid test is based on phenotype. Here the outward appearance of TT and Tt trees is tall and tt is arched. 

(c) Homozygotes and heterozygotes

Answer:  If both the genes of a pair of alleles are the same, it is called a homozygote. And if the two genes are different, it is called a heterozygote. For example, both TT and tt are homozygous. Both TT genes are tall and both tt genes are for stress syndrome Tt Both of these genes are heterozygous or heterozygous. This is because  it has a gene T for tall symptoms and the gene for pressure symptoms. so  it is heterozygous.

Additional FAQ:


1. Who is the inventor of heredity?

Answer: Gregor Johann Mendel.

2. What are hereditary traits transmitted through?

Answer: Through genes.

3. How many pairs of chromosomes are there in the human body?

Answer: 23 pairs.

4. The Where did Mendel publish his discoveries?

Answer: In the journal of the Natural History Society of Bonn.

5. What is Mendel’s monohybrid ratio?

Answer: 2:1 or 3:

6. What is Mendel’s dihybrid ratio?

Answer: 9:3:3:

7.How many types of cells are there in the human body?

Answer: There are two types.

8. Who is the father of good breeding science?

Answer: Sir Francis Galton.

 9. What is the number of sex chromosomes in a person with Clinfelter syndrome?

Answer: XXY or XXXY

10. What is the number of sex chromosomes in a person with Turner syndrome?

Answer: XO