In pedigree analysis,the symbol given for sex unspecified is

Marriages between close relatives and cousins are not advisable because

Which statement is correct regarding the inheritance of an autosome-linked recessive gene?

An albino father's daughter marries an albino man. What will be the ratio of their offspring?

Select the correct options for the given statements:
Statements:
$X$: Formation of Haemoglobin is controlled by two closely linked genes $HBA1$ and $HBA2$ on chromosome $16$ of each parent.
$Y$: $\beta$-Thalassemia is controlled by a single gene $HBB$ on chromosome $21$ of each parent.

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