An autosome is:

$A$ family has five daughters and is expecting a sixth child. What is the probability of it being a boy?

$A$ medical technician, while observing a human blood smear under the microscope, notes the presence of a Barr body close to the nuclear membrane in the $WBC$. This indicates that the person under investigation is:

$A$: $XO$ type sex determination is found in a large number of insects.
$R$: Some of the sperms bear the $X$-chromosome,whereas some do not.

What determines the sex of the embryo?

The male human is represented by which sex chromosomes?