In humans,color blindness is caused by:

Assertion $(A) :$ Phenylketonuria is an inborn error of metabolism and inherited as the autosomal dominant trait.
Reason $(R) :$ The disease is caused by mutation in the gene that codes for the enzyme phenylalanine hydroxylase.

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 (in $\%$)?

Which of the following is a Mendelian disorder?

Both husband and wife have normal vision,though their fathers were colour blind and their mothers did not have any gene for colour blindness. The probability of their daughters becoming colour blind is (in $\%$)

Sir Archibald Garrod is associated with which of the following fields?