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प्रश्न
Mention the total number of chromosomes along with the sex chromosomes that are present in a human female and a human male. Explain how in sexually producing organisms the number of chromosomes in the progeny remains the same as that of the parents.
उत्तर
The total number of chromosomes present in both human male and female is 46. Out of these, two chromosomes are the sex chromosomes. In human males, the two sex chromosomes present are X and Y, while in human female, both sex chromosomes are X.
During sexual reproduction, the new individual is formed by the fusion of gametes from both the parents. These gametes are haploid in nature, i.e. they contain only one set of the chromosomes. They are formed by the meiosis, a type of cell division which reduces chromosome number to half. When these haploid gametes fuse during fertilisation, the two nuclei of these two gametes fuse and the chromosome number is then restored to normal. Hence, the progeny formed has the same number of chromosomes as that of the parents.
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संबंधित प्रश्न
Where in the human body does an ovum get fertilised?
When a female child is born, her ovaries already contain thousands of immature eggs (or ova) contained in immature structures A. On maturing, A bursts open and an egg shoots out of the ovary in a process called B. The process B starts in the females at puberty and occurs again and again after a time period x. Before every occurrence of process B, the inner lining of uterus becomes thick and soft with lots of blood vessels in it. When the egg cell gets fertilised by a sperm, then an event C occurs in the life of mature human female which lasts for time period y leading to the birth of baby. If, however, the egg cell released by the ovary does not get a sperm to fuse with, then the thick and soft inner lining of uterus breaks down and comes out of the female's body in an event called D. The occurrence of event D is controlled by chemical substances E.
(a) What are A?
(b) What is process B?
(c) What is the time period x?
(d) Name the event C.
(e) How much is the time period y?
(f) What is the name of process D?
(g) Name the chemical substances E.
Explain how the transmission of virus and bacteria diseases be prevented?
Describe in brief the role of ureter in human male reproductive system.
Describe the role of the following in human beings:
(i) Seminal vesicles
(ii) Prostate gland
Choose the correct answer:
When pregnancy does not occur, the life of corpus luteum is about _____________
Give the function of the following:
Uterus
Give two important unique features of the human reproductive system.
Name the Following
What does this abbreviation stand for IUD?
Which one of the following statements about human sperm is correct?
