In a dihybrid cross between two heterozygous pea plants for seed shape (Rr) and seed colour (Yy), both parents having genotype RrYy, calculate the probability that a seed from the F1 generation is round and yellow, and the probability that it is round and green.

Step-by-step solution

1. Step 1: Treat the two traits as independently assorting loci.
2. Step 2: For seed shape, probability of round (R allele) = 3/4 (RR + Rr).
3. Step 3: For seed colour, probability of yellow (Y allele) = 3/4 (YY + Yy).
4. Step 4: Multiply independent probabilities for round‑yellow: $(3/4)\times (3/4)=9/16$ (≈ 0.5625).
5. Step 5: For round‑green, use round probability (3/4) and green probability (1/4) from Yy + yy: $(3/4)\times (1/4)=3/16$ (≈ 0.1875).
6. Step 6: Thus the seed is round and yellow with probability 9/16 and round and green with probability 3/16.

Concept tested: Independent assortment of two loci

Published 1 October 2026 · How this solution was prepared and checked