Question

in pea plants, round pods (r) are dominant to wrinkled pods (r) and yellow pods (y) are dominant to green pods (y). the punnett square below shows the possible gene combinations for a dihybrid cross between two parent plants that are heterozygous (rryy).

punnett square for a dihybrid cross

in each space below, enter the probability of producing the phenotype listed.

round and yellow offspring: \boxed{}/16
round and green offspring: \boxed{}/16
wrinkled and yellow offspring: \boxed{}/16
wrinkled and green offspring: \boxed{}/16

Explanation:

Step1: Count the number of each phenotype

• Round and yellow: Count all the genotypes that have at least one \(R\) (for round, since \(R\) is dominant over \(r\)) and at least one \(Y\) (for yellow, since \(Y\) is dominant over \(y\)).
• \(RRYY\): 4 times
• \(RRYy\): 4 times
• \(RrYY\): 2 times
• \(RrYy\): 2 times
• Total: \(4 + 4+2 + 2=8\)
• Round and green: Count all the genotypes that have at least one \(R\) and \(yy\).
• \(RRyy\): 0 times
• \(Rryy\): 2 times
• Total: \(2\)
• Wrinkled and yellow: Count all the genotypes that have \(rr\) and at least one \(Y\).
• \(rrYY\): 1 time
• \(rrYy\): 3 times
• Total: \(4\)
• Wrinkled and green: Count all the genotypes that have \(rr\) and \(yy\).
• \(rryy\): 2 times
• Total: \(2\)

Step2: Calculate the probability

Since there are 16 total squares in the Punnett square (total number of possible offspring combinations).

• Round and yellow: \(\frac{8}{16}\)
• Round and green: \(\frac{2}{16}\)
• Wrinkled and yellow: \(\frac{4}{16}\)
• Wrinkled and green: \(\frac{2}{16}\)

Answer:

Round and yellow offspring: \(\frac{8}{16}\)
Round and green offspring: \(\frac{2}{16}\)
Wrinkled and yellow offspring: \(\frac{4}{16}\)
Wrinkled and green offspring: \(\frac{2}{16}\)