Brown eye color dominates the blue and is determined by an autosomal gene. Polydactyly is determined by a dominant autosomal gene. From the marriage of brown-eyed parents with polydactyly was born a child with blue eyes and a normal hand. What offspring can you expect from this marriage? What is the probability of birth of brown-eyed children with a normal hand?

Answer:

According to the third law of Mendel, in dihybrid crosses the inheritance of both characters is carried out independently of each other, and in the offspring of digeterozygotes phenotypic splitting is observed in the proportion of 9: 3: 3: 1 (9 A * B *, 3 aaB *, 3 A * bb, 1 aabb, where * in this case means that the gene can be either in a dominant or in a recessive state).

Answer on the first and second question:

9 (Brown eyes, polydactyly) : 3 (Brown eyes, normal hand) : 3 (Blue eyes, polydactyly) : 1 (Blue eyes, normal hand)