Question

The recombinant phenotypic and genotypic ratio in F₂ obtained from parental cross having genotypes TTRR x ttrr will be

• A.

  Phenotypic ratio	Genotypic ratio
  9:3:3:1	1:2:2:4:1:2:1:2:1

• B.

  Phenotypic ratio	Genotypic ratio
  3:1	1:2:1

• C.

  Phenotypic ratio	Genotypic ratio
  3:3	1:2:3

• D.

  Phenotypic ratio	Genotypic ratio
  3:3	1:2:1:2

Answer 1

Answer: (D)

9:3:3:1 is the phenotypic ratio obtained in a dihybrid cross. Among these offsprings, 6 show recombinant phenotype in the ratio of 3:3. 9 and 1 represent the parental phenotype. The genotypic ratio for dihybrid cross will be:
TTRR:TtRR:TTRr:TtRr:TTrr:Ttrr:ttRR:ttRr:ttrr :: 1:2:2:4:1:2:1:2:1