Which of the following best describes incomplete dominance?

• A. One allele completely masks the effect of the other allele in a heterozygote.
• B. Both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits distinctly.
• C. A heterozygote displays a phenotype that is intermediate between the two homozygotes.
• D. The phenotype of the heterozygote is identical to that of one of the homozygotes.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of incomplete dominance. Incomplete dominance occurs when neither allele in a heterozygote completely masks the effect of the other. Instead, the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes.
2. Step 2: Compare incomplete dominance with other inheritance patterns. For example, in complete dominance, one allele completely masks the effect of the other, resulting in the phenotype of the dominant allele being expressed. In codominance, both alleles are fully expressed, and the phenotype shows both traits distinctly.
3. Step 3: Analyze the options provided in the problem. The first option describes complete dominance, where one allele masks the other. The second option describes codominance, where both alleles are fully expressed. The third option aligns with incomplete dominance, where the heterozygote displays an intermediate phenotype. The fourth option describes a scenario where the heterozygote's phenotype matches one of the homozygotes, which is not incomplete dominance.
4. Step 4: Focus on the correct description of incomplete dominance. The key characteristic is the intermediate phenotype in heterozygotes, which is a blend of the two homozygous phenotypes.
5. Step 5: Conclude that the correct answer is: 'A heterozygote displays a phenotype that is intermediate between the two homozygotes,' as this best describes incomplete dominance.