A heterozygous yellow round seeded pea plant (YyRr) is test crossed with a green wrinkled seeded plant (yyrr). What phenotypic ratio is expected in the progeny?

A dihybrid test cross with a fully heterozygous parent yields gametes YR, Yr, yR and yr in equal frequency. Each combines with the yr gamete from the recessive parent, producing four phenotypes in a 1:1:1:1 ratio.