Gene for colourblindness is located on
Homologous part of $X$-chromosome
Non-homologous part of $X$-chromosome
Homologous part of $Y$-chromosome
Non-homologous part of $Y$-chromosome
A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. Thus boy
Colour blindness results from
Which one of the following symbols and its representation, used in human pedigree analysis is correct ?
Colour blindness is found more in males than in females because
Haemophilia is more commonly seen in human males than in human females because