Question

a plant that has round and yellow seeds (rryy) is crossed with a plant that has round and yellow seeds (rryy). what is the ratio of the offspring that will have round and yellow seeds?
key: r = round
r = wrinkled
y = yellow
y = green

○ 1:16
○ 3:16
○ 8:16
○ 9:16

Explanation:

Step1: Analyze Rr cross

For the R (round) and r (wrinkled) alleles: Cross Rr × Rr. The Punnett square gives genotypes RR, Rr, Rr, rr. Phenotypically, round (RR, Rr, Rr) : wrinkled (rr) = 3:1. So probability of round (R_) is $\frac{3}{4}$.

Step2: Analyze Yy cross

For Y (yellow) and y (green) alleles: Cross Yy × Yy. Punnett square gives YY, Yy, Yy, yy. Phenotypically, yellow (YY, Yy, Yy) : green (yy) = 3:1. Probability of yellow (Y_) is $\frac{3}{4}$.

Step3: Combine probabilities

To get round and yellow (R_ Y_), multiply the probabilities: $\frac{3}{4} \times \frac{3}{4} = \frac{9}{16}$. So the ratio is 9:16.

Answer:

9:16