Question

In a complimentary gene interaction calculate the number of phenotype and genotype produced in a cross $AaBb\times aaBB$

• A. 1 phenotype, 2 genotypes
• B. 2 phenotypes, 4 genotypes
• C. 4 phenotypes, 4 genotypes
• D. 2 phenotypes, 2 genotypes

Answer 1

Answer: (B)

2 phenotypes, 4 genotypes

In complementary gene interaction, when both dominant alleles are present together, they produce a new phenotype. In this type, aaBB, aaBb, Aabb and aabb genotypes produce similar type of phenotype. The genotype AaBB, AABB, AaBb and AABb produce one type of phenotype. Hence, when a cross is made between AaBb and aaBB, the gametes produced will be AB, ab, Ab and aB x aB. In this the offsprings will have genotype, AaBB, aaBb, AaBb and aaBB and 2 types of phenotypes will be observed.

Thus, the correct answer is '2 phenotypes, 4 genotypes.'