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प्रश्न
How many pairs of chromosomes are present in human beings? Out of these how many are sex chromosomes?
उत्तर
- Human beings have 46 chromosomes (23 pairs) in each cell.
- Out of these, two (one pair) are sex chromosomes (XX in females, XY in males).
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संबंधित प्रश्न
What is the name of the process in which thickened uterus lining alongwith blood vessels is removed from the body of a human female through vaginal bleeding?
For how much time does menstruation last in human females (or women)?
Where does fertilisation take place in human females?
What joins embryo to placenta in mother's body?
The normal body cell of an organism contains 28 pairs of chromosomes. The number of chromosomes present in its germ cell will be
(a) 28
(b) 14
(c) 56
(d) 42
When a fertilised egg E formed in the oviduct of a human female divides repeatedly to form an embryo, the embryo gets implanted in the thick and soft lining of the uterus. After this a disc-like special tissue T develops between the uterus wall and embryo through which all the requirements of the developing embryo (and foetus) are met from the mother's body, The embryo is connected to the tissue T through a string like structure S.
(a) What is the other name of fertilised egg cell E?
(b) What is the name of tissue T?
(c) Name the string-like structure S.
(d) Name two substances which pass from mother's blood to embryo through tissue T and, one type of substance which passes from embryo to mother's blood.
(e) What happens to S when the baby is born? Why?
Give the functions of the following:
Vagina
Define the following:
Asexual reproduction
______ is a lytic enzyme released by the sperm.
