Genes R and Y follow independent assortment. If RRYY produce round yellow seeds and rryy produce wrinkled green seeds, what will be the phenotypic ratio of the F2 generation?
Answer: (A) Phenotypic ratio - 9 : 3 : 3 : 1. Answer: (A) Phenotypic ratio - 9 : 3 : 3 : 1 Solution: Genes R and Y assort independently, so crossing RRYY (round, yellow) with rryy (wrinkled, green) gives an F1 RrYy that on self-pollination produces an F2 with four phenotypic classes.
- A.Phenotypic ratio - 9 : 3 : 3 : 1✓
- B.Phenotypic ratio - 9 : 7
- C.Phenotypic ratio - 1 : 2 : 1
- D.Phenotypic ratio - 3 : 1
Correct Answer
(A) Phenotypic ratio - 9 : 3 : 3 : 1
Solution & Explanation
Answer: (A) Phenotypic ratio - 9 : 3 : 3 : 1 Solution: Genes R and Y assort independently, so crossing RRYY (round, yellow) with rryy (wrinkled, green) gives an F1 RrYy that on self-pollination produces an F2 with four phenotypic classes. The classic dihybrid F2 phenotypic ratio is 9 round-yellow : 3 round-green : 3 wrinkled-yellow : 1 wrinkled-green, i.e., 9:3:3:1. NCERT Reference: NCERT Class XII, Ch 4, p.64, lines 4-12: "appeared in the ratio 9:3:3:1" ... "(3 Round : 1 Wrinkled) (3 Yellow : 1 Green) = 9 Round, Yellow : 3 Wrinkled, Yellow: 3 Round, Green : 1 Wrinkled, Green"