Answer to Question 1
b
Answer to Question 2
An example of an autosomal recessive trait is phenylketonuria, in which affected individuals inherit one mutated copy of the phenylalanine hydroxylase gene from each parent (homozygous). The resulting inability to convert phenylalanine to tyrosine requires lifelong phenylalanine restriction to prevent mental retardation. Familial hypercholesterolemi a is an example of an autosomal dominant disorder and characterized by absence or mutation of LDL receptors leading to severely elevated LDL-cholesterol levels and risk of early myocardial infarction and death.