Which of the following crosses will yield four phenotypes in a ratio of 9:3:3:1?
A)RRYY * RRYY
B)RRYY * rryy
C)RrYy * RrYy
D)RrYy*rryy
E)rryy * rryy

Question

Quizplus · Accepted Answer

This is a classic dihybrid cross, where two traits are being analyzed. The cross in choice C is the only one that involves two heterozygous parents (RrYy x RrYy), which can produce four different phenotypic outcomes (RY, Ry, rY, and ry) in a 9:3:3:1 ratio. The other crosses either have homozygous parents (A and E) or are not true dihybrid crosses (B).

Which of the Following Crosses Will Yield Four Phenotypes in a Ratio