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प्रश्न
Write a short note on sex determination in man.
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उत्तर
The difference between two individuals of the same species with respect to heredity is known as sex. So, an individual can either be a male or female in normal circumstances. Scientists have discovered that sex is transmitted by definite sex determination, also called heterosomes. The human body cells have two sex- chromosomes. A woman has two X- chromosomes while a man has one X- chromosome and one Y-chromosome.
Therefore, an egg cell has one X- chromosome and a sperm cell have either an X- or a Y-chromosome. This means that the sex of a baby is determined by the type of sperm cell fertilizing the egg. If an egg, fused with a sperm having Y-chromosome, then the male zygote will develop and when fused with a sperm having an X-chromosome then a female zygote will develop.
APPEARS IN
संबंधित प्रश्न
There are ................ pairs of chromosomes in the human being.
Which of the two, sperm or ovum, decides the sex of the child?
A zygote which has inherited an X chromosome from the father will develop into :
(a) baby boy
(b) baby girl
(c) adult
(d) either boy or girl
A family consists of two parents and their five children and the pedigree chart below shows the inheritance of the trait colour blindness in them.
Who is colour blind in the parents – the Father or the Mother?
________ shows haplo-diploid type of sex-determination.
Match the items of Column I with Column II:
| Column I | Column II | ||
| i. | XX-XO method of Sex Determination | a. | Turner syndrome |
| ii. | XX-XY method of Sex Determination | b. | Female heterog ametic |
| iii. | karyotype-45 | c. | Grasshopper |
| iv. | ZW-ZZ method of Sex Determination | d. | Female homogametic |
The maleness of a child is determined by
Which of the following statements is not true with respect to variation?
Sex of an individual is determined by different factors in various species. Some animals rely entirely on the environmental ones, while in some other animals the individuals can change their sex during their life time indicating that sex of some species is not genetically determined. However in human beings, the sex of an individual is largely determined genetically.
- In what way are the sex chromosomes 'X' and 'Y' different in size? Name the mismatched pair of sex chromosome in humans.
- Write the number of pair/pairs of sex chromosomes present in human beings. In which one of the parent (male/female) perfect pair/pairs of sex chromosome are present?
- Citing two examples, justify the statement "Sex of an individual is not always determined genetically".
OR
Draw a flow chart to show that sex is determined genetically in human beings.
What is sex determination? Explain the mechanism of sex determination in the case of birds.
