What type of dominance occurs when the phenotype of heterozygous individuals is intermediate between those of the homozygotes?

What type of dominance occurs when the phenotype of heterozygous individuals is intermediate between those of the homozygotes?

• A. Codominance
• B. Incomplete Dominance
• C. Polygenic Inheritance
• D. Sex-Linked Traits

Answer: (B)

Incomplete dominance occurs when the phenotype of heterozygous individuals is intermediate between those of the homozygotes. In this genetic scenario, neither allele is completely dominant over the other, leading to a blending of traits in the phenotype. A classic example of incomplete dominance can be seen in the flower color of snapdragons, where a cross between red (homozygous) and white (homozygous) flowers results in offspring with pink flowers (heterozygous), illustrating the intermediate phenotype. In contrast, codominance involves both alleles being fully expressed in the phenotype of heterozygotes, resulting in traits that are both present rather than an intermediate form. Polygenic inheritance refers to traits that are influenced by multiple genes, leading to a continuous range of phenotypes rather than discrete categories. Sex-linked traits are associated with genes located on sex chromosomes, displaying patterns of inheritance that are dependent on the sex of the individual. These distinctions clarify why the second option aligns with the definition provided in the question.

Incomplete dominance occurs when the phenotype of heterozygous individuals is intermediate between those of the homozygotes. In this genetic scenario, neither allele is completely dominant over the other, leading to a blending of traits in the phenotype. A classic example of incomplete dominance can be seen in the flower color of snapdragons, where a cross between red (homozygous) and white (homozygous) flowers results in offspring with pink flowers (heterozygous), illustrating the intermediate phenotype.

In contrast, codominance involves both alleles being fully expressed in the phenotype of heterozygotes, resulting in traits that are both present rather than an intermediate form. Polygenic inheritance refers to traits that are influenced by multiple genes, leading to a continuous range of phenotypes rather than discrete categories. Sex-linked traits are associated with genes located on sex chromosomes, displaying patterns of inheritance that are dependent on the sex of the individual. These distinctions clarify why the second option aligns with the definition provided in the question.