Question

in pea plants, the allele for round seeds (r) is dominant to wrinkled seeds (r), and the allele for yellow seeds (y) is dominant to green seeds (y). if two heterozygous plants (rryy × rryy) are crossed, what fraction of the offspring are expected to have round, yellow seeds? 3/16 1/16 9/16 12/16

Explanation:

Step1: Isolate seed shape trait

We focus on the R/r alleles (round/wrinkled). For a cross of Rr × Rr, the probability of round seeds (RR or Rr) is calculated as:
$P(\text{round}) = \frac{3}{4}$

Step2: Isolate seed color trait

We focus on the Y/y alleles (yellow/green). For a cross of Yy × Yy, the probability of yellow seeds (YY or Yy) is calculated as:
$P(\text{yellow}) = \frac{3}{4}$

Step3: Combine independent probabilities

Since the traits are independent, multiply the two probabilities to get the combined probability of round, yellow seeds:
$P(\text{round and yellow}) = \frac{3}{4} \times \frac{3}{4} = \frac{9}{16}$

Answer:

$\frac{9}{16}$