Category: Biology Second Paper

A normal male (XY) married to another color blind (XcXc) female produces a color blind son (XcY) and a color blind carrier daughter (XcX) in the F1 lineage. Intermarriage between the F1 progeny results in F2 progeny with 1 normal son, 1 normal daughter, 1 color blind son and 1 color blind daughter.

here,

A normal male has a genotype of XY

Genotype XcXc of a color blind woman

The first progeny is F1 and the second progeny is F2

Parents :           ♂     ×             ♀

Phenotype: Normal       color blindness

Genotype :       XY             XcXc

Gamit :        (X) (Y)         (Xc) (Xc)

F1 Generation : XcX XcY

 

Self fertilization : F1×F1

Parents :              ♂         ×     ♀

Phenotype:  color blind      carrier

Genotype :         XcY         XcX

Gamit :          (Xc) (Y)    (Xc) (X)

F2 Generatin (checker board)

Comment: From the checker board, out of 4 children, 1 normal son, 1 normal daughter, 1 color blind son and 1 color blind daughter. Color blindness requires one Xc gene in males and two Xc genes in females.

Phenotypic Ratio : Normal Son : Normal Daughter : Color Blind Son : Color Blind Daughter = 1:1:1:1

A colorblind male (XcY) married to a normal (XX) female produces an F1 offspring with a normal son (XY) and a colorblind carrier daughter (XcX). Intermarriage between the F1 offspring results in 1 normal son, 2 normal daughters and 1 color-blind son in the F2 progeny.
here,
Genotype XcY of a color blind male
A normal female has a genotype of XX
The first progeny is F1 and the second progeny is F2

Parents : ♂ × ♀
Phenotype: Normal color blindness
Genotype : XcY XX
Gamit : (Xc) (Y) (X) (X)
F1 progeny : XcX XY
(carrier daughter) (natural son)
Svanishek : F1×F1
Parents : ♂ × ♀
Phenotype: Normal carrier
Genotype : XY XcX
Gamit : (X) (Y) (Xc) (X) )
F2 progeny (checker board)
Comment: From the checker board, out of 4 children, 1 normal son, 2 normal daughters and 1 color blind son. Color blindness requires one Xc gene in males and two Xc genes in females.
Phenotypic ratio : Normal son : Normal daughter : Color blind son = 1 : 2 : 1

The mutation stops the development of the color-sensitive cells in the human retina, and people with the latent gene cannot distinguish particular colors. It is called color blindness. John Dalton described human color blindness. It is called Daltonism. 95% of color blind people are red-green color blind. There is no cure for color blindness or people who are color blind are never cured. The best test for color blindness is the Ishihara color test.

1. Color blindness: Can’t tell the difference between different colors.
2. Haemophilia: Delayed blood clotting at the wound site.
3. Dysplasia: Absence of sweat glands and teeth.
4. Spastic paraplegia: partial paralysis of muscles and irregular stiffness.
5. Ratkana : Sees something unclear at night.
6. Optic Atrophy: The optic nerve starts to deteriorate.
7. Juvenile glaucoma: Hardness of the eyeball
8. White Forelock: A bunch of white hair is seen at the front of the head.
9. Myopia: weak vision.
10. Muscular dystrophy: Muscular complications, the child’s mobility disappears at the age of 10 years.

1. Sex-linked traits are carried by the X chromosome, sometimes by the Y chromosome.
2. This gene is latent in most cases.
3. Sex-linked traits are more pronounced in males.
4. All sons of wives with the sex-linked trait will express the trait, but daughters will be carriers.
5. A father’s sex-linked traits are transmitted to daughters. This is called criss-cross inheritance.

Genes located on sex chromosomes are called sex genes. Traits controlled by sex chromosomes are called sex-linked traits. Intergenerational transmission of sex-linked traits through sex chromosomes is called sex-linked inheritance. Hereditary diseases transmitted from generation to generation through sex chromosomes are called sex-linked disorders or sex-linked abnormalities.

According to this system female is homogametic or XX and male has X chromosome and not Y. Females produce the same type of egg (X) and males produce two types of sperm (X and A). When a woman’s egg X meets a man’s sperm X, a female child (XX) will be produced. Again, the union of the woman’s egg X with the man’s sperm A will produce a son (XA). This method determines the sex of animals like grasshoppers, beetles, Orthoptera, Heteroptera, Dioscorea (plants).

According to this system female is homogametic or XX and male is heterogametic or XY. Females produce one type of egg (X) and males produce two types of sperm (X and Y). When a woman’s egg X meets a man’s sperm X, a female child (XX) will be produced. Again, the union of the woman’s egg X with the man’s sperm Y will produce a son (XY). This method determines the sex of animals such as humans, Drosophila, various insects, cannabis, cockroaches, Elodea etc.

The genetic process in which the sex of an organism is determined is called sex determination. Miss N. M. Stevell and Wilson proposed the theory of sex determination in insects after extensive research. According to this doctrine, the method of gender determination is sterile.

1. XX-XY System: According to this system female is homogametic or XX and male is heterogametic or XY. Females produce one type of egg (X) and males produce two types of sperm (X and Y). When a woman’s egg X meets a man’s sperm X, a female child (XX) will be produced. Again, the union of the woman’s egg X with the man’s sperm Y will produce a son (XY). This method determines the sex of animals such as humans, Drosophila, various insects, cannabis, cockroaches, Elodea etc.
2. XX-X0 System: According to this system female is homogametic or XX and male has X chromosome and not Y. Females produce the same type of egg (X) and males produce two types of sperm (X and A). When a woman’s egg X meets a man’s sperm X, a female child (XX) will be produced. Again, the union of the woman’s egg X with the man’s sperm A will produce a son (XA). This method determines the sex of animals like grasshoppers, beetles, Orthoptera, Heteroptera, Dioscorea (plants).

Animals that produce different types of gametes are called heterogametic sex. Male members are the heterogametic sex. Their gametes are called heterogametes.