Question

The phenotypic ratio of a dihybrid cross beween two heterozygous individuals is

• A. 3:1
• B. 1:2:1
• C. 3:3:1
• D. 9:3:3:1
• E. 6:4:4:2

Answer 1

Answer: (D)

9:3:3:1

The F${}_2$ generation of a dihybrid cross, with dominance in the two traits, will result in a: Phenotypic ratio of 9:3:3:1 and the genotypic ratio of 1:2:2:1:4:1:2:2:l. This type of dihybrid cross leads to the Law of Independent Assortment, which states that "the emergence of one trait will not affect the emergence of another". The members of an allelic pair segregate independently of members of another allelic pair. All possible allelic combinations can occur in the reproductive cells. Thus, the correct answer is option D.