What is the cause of haemophilia
Chromosomal aberration
Somatic mutation
$X$-linked mutation
All the above
In pedigree analysis, the square, blackened and horizontal lines represents
Given below is a highly simplified representation of the human sex chromosomes from a karyotype.
The genes $a$ and $b$ could be of
The most striking example of point mutation is found in a disease called
Mr. Stevan is suffering from haemophilia and cystic fibrosis. His father is hetrozygous for cystic fibrosis. The probability of Stevan's sperm having recessive $X-$linked as well as autosomal allele is
Given below is a pedigree chart showing the inheritance of a certain sex- linked trait in humans.
The trait traced in the above pedigree chart is