Question

The phenotypic ratio obtained by crossing Mendel’s $F_1$ dihybrid with the recessive parent is

• A. 9:3:3:1
• B. 3:1
• C. 1:1:1:1
• D. 9:7

Answer 1

The correct option is C

1:1:1:1

The genotype of $F_1$ dihybrid is YyRr and it produces 4 types of gametes, YR, Yr, yR, yr. The recessive parent produces only one type of gamete (yr). Thus the progeny exhibit 4 different genotypes and phenotypes in equal proportions, making it a ratio of 1:1:1:1, YyRr, Yyrr, yyRr, yyrr respectively.