What would you do to determine whether a black horse is pure

What would you do to determine whether a black horse is pure bred for color? (Black is dominant; gray is recessive). Muscular dystrophy (certain types) is sex-linked. Unfortunately, most males die by age 17. Show, through Punnett squares, how females do not get this disorder. Be creative and make up a new allele that confers a heterozygote advantage. State what happens when people are homozygous in both the dominant and recessive states.

Solution

Ques-3:

Test cross is done to determine the genotype (weather homozygous or heterozygous) of the individual in question mark. If the cross between the dominant trait and recessive individual results in both dominant and recessive phenotypes (in 1:1 ratio) in the offspring, the individual in question mark is “heterozygous,” means not a pure breed. If the resulting offspring show only the dominant character, the individual in question is \"homozygous for the dominant allele\" and is a pure breed.

For example, assume that the gene coding for gray horse is G and black horse is g; G is dominant over g.

Gg* gg ----> Gg (1/2) and gg (1/2) ----> Not a pure breed

GG*gg ---> Gg (100%) ---> Pure breed