In pea plants, round seeds (R) are dominant to wrinkled seeds (r) and yellow seeds (Y) are dominant to green seeds (y). Two plants heterozygous for both genes (RrYy) are crossed and produce 320 seeds. How many seeds are expected to be round and green?
Answer and explanation
Correct answer: A.
- Step 1: A dihybrid cross of RrYy x RrYy gives the ratio 9 round yellow : 3 round green : 3 wrinkled yellow : 1 wrinkled green. Step 2. Round green seeds are of the total: . **Answer: . Why not the others:** is the that are round and yellow, is the that are wrinkled and green, and is the quarter of all seeds that are green, whether round or wrinkled.
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