Question

Crossing between AABB, the probability of AaBb in F2 generation would be
A. 1/16
B. 2/16
C. 8/16
D. 4/16

Answer 1

When two pairs of genes determine the phenotype so that either of the two genes in the dominant condition is able to produce the phenotypic trait, then the phenomenon is said to be duplicate dominant interaction.

Complete answer: The shepherd's purse capsule occurs in two different shapes, i.e., triangular and top-shaped. When these two different capsules cross with each other, the F1 generation produced the F2 generation with the triangular and top-shaped capsules in the ratio (Triangular) 15:1 (Top shaped). Two independently segregating dominant genes (AandB) have been found to influence the shape of the capsule in the same way. All genotypes having dominant alleles of both or either of these genes (A and B) would produce plants with triangular-shaped capsules. Genotype ab would produce plants with top-shaped capsules. The results of this are given below.
Parents: Triangular (AABB) X Top-shaped (aabb)
Gametes: AB and ab

Gametes	AB Ab aB ab
ABAbaBab	AABBTriangular
AABbTriangular	AAbbTriangular
AaBBTriangular	AaBbTriangular
AaBbTriangular	AabbTriangular

Hence, the correct answer is option D.

Note: Duplicate genes are examples of non-allelic interaction. Non- allelic interaction is an interaction between genes located at different loci on the same chromosome or on different but non-homologous chromosomes controlling a single phenotype to produce a different expression.