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प्रश्न
During reproduction, the chromosome number (2n) reduces to half (n) in the gametes and again the original number (2n) is restored in the offspring. What are the processes through which these events take place?
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उत्तर
During gametogenesis, the chromosomal number is reduced by half and then regained through fertilisation.
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संबंधित प्रश्न
Women are often blamed for producing female children. Consequently, they are ill-treated and ostracized. How will you address this issue scientifically if you were to conduct an awareness programme to highlight the values involved?
Draw a labelled diagram of sperm.
In case of sexual reproduction, newborn show similarities about characters. Explain this statement with suitable examples.
Give scientific reason.
There is a menopause when women are 45-50 years old.
If one pollen grain produces two male gametes, how many pollen grains are needed to fertilize 10 ovules?
The male sex hormone testosterone is secreted from ____________.
Mammalian egg is ____________.
The Androgen Binding Protein (ABP) is produced by ____________.
Answer the following type of question Assertion (A) and Reason (R).
(A) - In human males, testes are extra-abdominal and lie in scrotal sacs.
(R) - Scrotum acts as a thermoregulator and keeps the temperature lower by 2°C for normal sperm production.
Expand the acronym.
LH
The immature male germ cells differentiates into ______ at the end of meiosis I.
Which of the following is diploid?
Extrusion of second polar body from egg nucleus occurs ______.
Which of the following stage of oogenesis forms a membrane called zona pellucida surrounding it?
Identify the wrong statement from the following.
Spermiation is the process of the release of sperm from ______.
Cells of corona radiata remain grouped together by ______.
At the time of organogenesis, genes regulate the process at different levels and at different time due to ______.
Preparation of sperm before penetration of ovum is ______.
The process of release of spermatozoa from Sertoli cells into cavity of the seminiferous tubules is called ______.
Sperms can be stored for several years in liquid nitrogen with a temperature of ______.
In spermatogenesis, at the end of the first meiotic division ______ are formed.
Given below are two statements.
- Statement I: The spermatids are non-motile and non-functional which get transformed into functional spermatozoa by the process of spermiogenesis.
- Statement II: During the process of this change, the spermatids remain held to each other and to Leydig's cells by cytoplasmic bridges.
In light of the above statements, select the correct answer from the option given below.
Answer the following:
How many primary spermatocytes and oocytes are required for the formation of 100 spermatozoa and ova?
Explain Oogenesis with diagram.
Draw a labelled diagram of a section through the ovary.
Select a correct pair of cells with identical set of chromosomes.
