CBSE Class 10 Science 2015 Term II Delhi Set 1

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Question : 21
Total: 36
How many pairs of chromosomes are present in human beings ? Out of these how many are sex chromosomes? How many types of sex chromosomes are found in human beings ?
"The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it." Draw a flow chart showing determination of sex of a newborn to justify this statement.
Solution:  
There are 23 pairs of chromosomes in human beings, out of these one pair of sex chromosome is there.
Female has one type of chromosome i.e., X and male has two types of chromosomes i.e., X and Y. Thus, sex of the child depends on the sex chromosomes of the father.
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