Sickle cell-anaemia disorder arises due to

Which is correct for inheritance of autosome linked recessive gene?

Phenylketonuria is a genetic disorder due to a defect in metabolism of the following.

If a boy's father has haemophilia and his mother has one gene for haemophilia; what is the chance that the boy will inherit the disease

A normal woman, whose father was colour-blind is married to a normal man. The sons would be