A dominant trait,Huntington disease,causes severe neural/brain damage at approximately age 40.The gene that causes this disease is not located on the sex chromosomes.A female whose mother has Huntington disease marries a male whose parents are normal.It is not known if the female has the disease.Assuming the female's mother was a heterozygote,and her father was normal,what is the probability that their firstborn will inherit the gene that causes Huntington disease?
Assume that in guinea pigs,dark brown fur (B)is dominant to black fur (b).If you mate a black guinea pig with a homozygous brown guinea pig,what proportion of the progeny will be homozygous?