Final answer:
The offspring of red and white snapdragons being pink represents incomplete dominance, a form of genetic inheritance where the heterozygote's phenotype is an intermediate of its parents. Genotypic and phenotypic ratios from a self-cross of heterozygotes follow a 1:2:1 pattern, contrasting with codominance, where both alleles are fully expressed in the phenotype.
Step-by-step explanation:
The cross between a red and a white snapdragon that results in a pink offspring is an example of incomplete dominance. Incomplete dominance is a pattern of inheritance where the phenotype of the heterozygote (CRCW) is intermediate between the two homozygote parents (CRCR for red and CWCW for white). The heterozygote snapdragon displays pink flowers because the red allele is not completely dominant over the white allele, resulting in a mixture of the two colors. The genotypic ratio from a heterozygote self-cross would be 1:2:1 (CR CR: CRCW: CW CW), and the corresponding phenotypic ratio would be red:pink:white.
Sickle cell anemia is another example of incomplete dominance where the blood protein hemoglobin is produced incorrectly, causing red blood cells to have a sickle shape. Moreover, codominance differs from incomplete dominance in that both alleles are fully expressed in the phenotype, as demonstrated in the MN and ABO blood groups of humans. In codominance, a heterozygote expresses both alleles equally, such as the LMLN genotype expressing both M and N antigens on red blood cells.