Question

The phenotypic ratio obtained in the ${\text{F}}_2$ generation for a dihybrid cross between round yellow seeds and green wrinkled seeds is:

• A. 9:3:3:3
• B. 9:3:3:1
• C. 9:5:3:1
• D. 9:3:4:3

Answer 1

The correct option is B 9:3:3:1

$\bullet$ In Mendel's dihybrid cross, the parents were - pea plants with yellow coloured round seeds (RRYY) and green coloured wrinkled seeds (rryy).
Hence, the ${\text{F}}_1$ progeny obtained had round and yellow seeds (RrYy).

$\bullet$ Selfing of the ${\text{F}}_1$ plants gave ${\text{F}}_2$ progenies exhibiting 4 different phenotypes: Round yellow (9), wrinkled yellow (3), round green (3), and wrinkled green seeded plants (1). Hence, the phenotypic ratio is 9:3:3:1.