Down's syndrome is caused by an extra copy of | vedclass

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(D) Down's syndrome is a chromosomal disorder caused by trisomy of chromosome $21$. An affected mother has $47$ chromosomes (including an extra $21$st

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$50$

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(D) Down's syndrome is a chromosomal disorder caused by trisomy of chromosome $21$. An affected mother has $47$ chromosomes (including an extra $21$st chromosome),while a normal father has $46$ chromosomes. During meiosis in the mother,the gametes produced will have either $23$ or $24$ chromosomes. Specifically,$50\%$ of the eggs will carry the extra $21$st chromosome. When these eggs are fertilized by normal sperm ($23$ chromosomes) from the father,$50\%$ of the resulting zygotes will have $47$ chromosomes (trisomy $21$),leading to Down's syndrome. Therefore,$50\%$ of the offspring are expected to be affected.

Column-$I$ (Disorder)	Column-$II$ (Ploidy)
$P$. Down's syndrome	$I$. Sex chromosomal trisomy
$Q$. Klinefelter's syndrome	$II$. Sex chromosomal monosomy
$R$. Turner's syndrome	$III$. Autosomal trisomy

Down's syndrome is caused by an extra copy of chromosome number $21$. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder (in $\%$)?

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Match the following columns:

Column-$I$ (Disorder) Column-$II$ (Ploidy)

$P$. Down's syndrome $I$. Sex chromosomal trisomy

$Q$. Klinefelter's syndrome $II$. Sex chromosomal monosomy

$R$. Turner's syndrome $III$. Autosomal trisomy

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