If a colourblind man marries a woman who is homozygous for normal colour vision, the probability of their son being colourblind is
$0$
$0.5$
$0.75$
$1$
A person may have one gene for normal haemoglobin and one gene for sickle cell haemoglobin. This heterozygous condition is called
Most studies on human genetics have been made through
If a normal women marries a colourblind man
Carrier of genes of colour blindness are present in