In carnations, the alleles for flower color exhibit incomplete dominance. Red flowers have the RR genotype. Pink flowers have the RW genotype. White flowers have the WW genotype.

If two pink flowers are crossed, what is the expected genotypic ratio of their offspring?

A. 0 RR : 4 RW : 0 WW
B. 1 RR : 2 RW : 1 WW
C. 2 RR : 0 RW : 2 WW
D. 3 RR : 0 RW : 1 WW

The expected genotypic ratio for the offspring of two pink carnations (RW crossed with RW) exhibiting incomplete dominance in flower color is 1 RR : 2 RW : 1 WW.

Explanation:

When two pink carnations with the genotype RW are crossed, we can predict the expected genotypic ratio of their offspring by using a Punnett square. In incomplete dominance, the heterozygote (RW) exhibits a blending of the two parental phenotypes, therefore red and white alleles produce a pink phenotype.

Crossing two RW heterozygotes, the genotypes of the offspring can be given by the following Punnett square:

R W
R RR RW
W RW WW

This results in one red flower (RR), two pink flowers (RW), and one white flower (WW). The expected genotypic ratio of their offspring is thus 1 RR : 2 RW : 1 WW.