If the number of chromosomes in most body cells of a mammal is $40$, the cells in the seminiferous tubule will have
$40$ chromosomes
$20$ chromosomes
$10$ chromosomes
While some other will have $20$
Loss of a $X$ chromosome in a particular cell during its development, results into
Mating among close relations is referred
Change of male and female parents during crosses is known as
Assertion : Phenylketonuria is a recessive hereditary disease caused by body’s failure to oxidize an amino acid phenylalanine to tyrosine, because of a defective enzyme.
Reason : It results in the presence of phenylalanine acid in urine.
When an albino female plant of maizeis crossed with normal green male plant, all plants in the progeny are albino because