. It is a matter of chance whether a couple will give birth to a male child or a


It is a matter of chance whether a couple will give birth to a male child or a female child." Justify this statement with the help of a flow chart showing the fusion of sex chromosomes

Best Answer

(i) A male has one X-chromosome and one Y-chromosome. Thus half the male gametes have X-chromosomes and the other half have Y-chromosomes. 

 

(ii) A female   has   two   X-chromosomes.  Thus   all   female   gametes have   only   X­ chromosomes.

 

(iii) If a sperm carrying Y-chromosome fertilises an ovum carrying X-chromosome, then the child born will be a boy. 

 

(iv) If a sperm carrying X-chromosome fertilises an ovum carrying X-chromosome, then the child born will  be a girl.

 

If a sperm carrying X-chromosome fertilises an ovum carrying

 

Therefore it is the sperm from the father which  determines the sex of the child

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