The Bases of Human Behaviour — Psychology STD 11 Humanities — Question
CBSE BoardEnglish MediumSTD 11 HumanitiesPsychologyThe Bases of Human Behaviour3 Marks
Question
Write a short note on chromosomes.
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Answer
Most of the cells in our body contain $23$ pairs of chromosomes:
Chromosomes are the hereditary elements of the body.
The genetic cells (sperm and ovum) have $23$ chromosomes but not in pairs.
A new generation results from the fusion of a sperm cell and an egg cell.
At the time of conception the organism inherits $46$ chromosomes from parents, $23$ from the mother and $23$ from the father.
The $23^{rd}$ chromosomes of the sperm cell can be either the X or Y type. If the X type sperm fertlise the egg cell, the fertilized egg will have an XX $23^{rd}$ chromosomes pair, and the child will be a female. And, if a Y type sperm fertilises the egg, the $23^{rd}$ chromosome pair will be XY, and the child will be a male. So, it is the sperm that decides whether the offspring will be a male or a female.
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