Question

Difficulty: MediumIncomplete Dominance, Codominance, and Multiple Alleles

Match each non-Mendelian genetic concept on the left with its correct phenotypic expression pattern or population characteristic on the right.

  • Incomplete DominanceHeterozygous individuals express an intermediate phenotype distinct from both homozygous parental phenotypes.
  • CodominanceHeterozygous individuals simultaneously express both parental alleles fully and distinctly without blending.
  • Multiple AllelesMore than two alternative gene forms exist for a single gene locus across individuals in a population.

Answer

Incomplete Dominance matches with the statement describing an intermediate phenotype distinct from both parents; Codominance matches with the statement describing simultaneous and full expression of both parental alleles without blending; Multiple Alleles matches with the statement describing more than two alternative gene forms existing at a single locus within a population.
Incomplete dominance produces a blended intermediate phenotype in heterozygotes. Codominance leads to the simultaneous, distinct expression of both alleles without blending. Multiple alleles refer to the existence of more than two gene variants at a given locus within a population.

Step-by-Step Solution

1
Analyze Incomplete Dominance
In incomplete dominance, the heterozygous phenotype is a blend or quantitative intermediate between the two homozygous traits.
Neither allele completely masks the expression of the other, resulting in a distinct third phenotype.
2
Analyze Codominance
In codominance, both alleles are fully expressed alongside each other without producing an intermediate blend.
Both gene products are fully functional and observable simultaneously in the heterozygote.
3
Analyze Multiple Alleles
Multiple alleles describe genetic systems where three or more alleles exist at the same locus across a population.
While an individual carries at most two alleles, population gene pools can contain several alternative allele variants (e.g., IAI^A, IBI^B, and ii in ABO blood grouping).

Key Concept

Non-Mendelian Inheritance Modes
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