Question

the dominant allele for yellow seed color is y, and the recessive allele for green color is y. the dominant allele for round seeds is r, and the recessive allele for wrinkled shape is r. if two plants crossed had a rryy genotype, what ratios of traits would be observed in the offspring? a 9 green, round seeds; 3 green, wrinkled seeds; 3 yellow, round seeds; 1 yellow, wrinkled seed b 9 yellow, wrinkled seeds; 3 yellow, round seeds; 3 green, wrinkled seeds; 1 green, round seed c 4 yellow, round seeds; 4 yellow, wrinkled seeds; 4 green, round seeds; 4 green, wrinkled seeds d 9 yellow, round seeds; 3 yellow, wrinkled seeds; 3 green, round seeds; 1 green, wrinkled seed

Explanation:

Step1: Determine gametes

The genotype of the cross is Rryy. The possible gametes are Ry and ry. When self - crossed, we use a Punnett - square analysis. But we can also use the product rule of probability for independent events. For seed color, the cross is Yy×Yy and for seed shape is Rr×rr (since one parent is Rryy). For the Yy×Yy cross, the ratio of yellow (Y -) to green (yy) is 3:1. For the Rr×rr cross, the ratio of round (Rr) to wrinkled (rr) is 1:1.

Step2: Calculate the combined ratio

Using the product rule, for the two - trait cross, the ratio of yellow round : yellow wrinkled : green round : green wrinkled is (3 yellow : 1 green)×(1 round : 1 wrinkled). So we have (3×1) yellow round : (3×1) yellow wrinkled : (1×1) green round : (1×1) green wrinkled, which gives a ratio of 3 yellow, round seeds : 3 yellow, wrinkled seeds : 1 green, round seed : 1 green, wrinkled seed.

Answer:

d