Both husband and wife have normal vision though their fathers were colourblind and mothers did not have any gene for colour blindness. The probability of their daughter becoming colourblind is
$50\, \%$
$75\, \%$
$25 \,\%$
None of these
Which one of the following symbols represents mating between relatives in human pedigree analysis?
Gene for colourblindness is located on
If a father and son are both defective in red-green colour vision, is it likely that the son inherited the trait from his father ? Comment.
A haemophilic woman marries a normal man, then
A person may have one gene for normal haemoglobin and one gene for sickle cell haemoglobin. This heterozygous condition is called