Differentiate between incomplete dominance and codominance with an example for each.

Differentiate between incomplete dominance and codominance with an example for each.

• A. Incomplete dominance: heterozygote shows intermediate phenotype; Codominance: both alleles are expressed
• B. Incomplete dominance: both alleles expressed; Codominance: heterozygote shows intermediate phenotype
• C. Incomplete dominance: recessive allele is masked in heterozygotes
• D. Codominance: both alleles expressed, but dominant allele masks the other

Answer: (A)

How alleles are expressed in heterozygotes distinguishes incomplete dominance from codominance. In incomplete dominance, the heterozygote shows an intermediate phenotype between the two homozygotes. A classic example is snapdragon flowers: red is produced by one allele, white by the other, and the heterozygote yields pink flowers, a blend of the two parental colors. In codominance, however, both alleles are expressed fully and distinctly in the heterozygote, so you see both traits at once. A well-known example is the AB blood type, where red blood cells carry both A and B antigens on their surface, displaying both traits rather than a blend.

How alleles are expressed in heterozygotes distinguishes incomplete dominance from codominance. In incomplete dominance, the heterozygote shows an intermediate phenotype between the two homozygotes. A classic example is snapdragon flowers: red is produced by one allele, white by the other, and the heterozygote yields pink flowers, a blend of the two parental colors. In codominance, however, both alleles are expressed fully and distinctly in the heterozygote, so you see both traits at once. A well-known example is the AB blood type, where red blood cells carry both A and B antigens on their surface, displaying both traits rather than a blend.