In a heterozygous genotype, both alleles are expressed equally to produce an intermediate phenotype

• A. Incomplete dominance
• B. Codominance
• C. Polygenic inheritance
• D. Complete dominance

Answer: (A)

When neither allele completely dominates, the heterozygous genotype can produce a blend of traits, giving an intermediate phenotype. This is called incomplete dominance. In this pattern, each allele contributes to the phenotype, so the heterozygote sits midway between the two homozygous forms—for example, red and white alleles producing pink flowers.

If both alleles were fully expressed in the heterozygote, you’d have codominance, where the traits appear together rather than as a blend (like both red and white kept distinct). Polygenic inheritance involves many genes adding up to influence a trait, not just a single gene with two alleles. Complete dominance would mean the heterozygote looks like the dominant homozygote, with no intermediate form.