Question

In a dihybrid cross between RRYY and rryy, the number of RrYy $F_2$ genotypes will be

• A. 4
• B. 3
• C. 2
• D. 9

Answer 1

Answer: (A)

4

In a dihybrid cross, a plant with yellow colour round seeds(YYRR) is crossed to green colour wrinkled(yyrr) seeds. In the F1 generation, plant with yellow colour wrinkled seeds(YyRr) are formed. When F1 plant is subjected to self pollination, in the F₂ generation 1YYRR, 2 YYRr, 2YyRR, 4YyRr, 1YYrr, 2Yyrr, 1yyRR, 2yyRr, 1yyrr are formed genotypically and 9 plants are Yellow round, 3 plants are yellow wrinkled, 3 plants are green round and 1 plant is green wrinkled are formed phenotypically.

So, the correct option is ‘4’.