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NEETZoologyPrinciples of Inheritance and Variation

A plant heterozygous for two independently assorting genes is self-pollinated. The resulting F₂ generation displays exactly 9 distinct phenotypic categories. Which of the following best describes the inheritance pattern of these two genes?

Options

  1. ABoth genes exhibit incomplete dominance or co-dominance.
  2. BBoth genes exhibit complete dominance over their respective recessive alleles.
  3. COne gene exhibits complete dominance while the other exhibits incomplete dominance.
  4. DBoth genes are polygenes contributing cumulatively to a single quantitative trait.

Correct answer

A. Both genes exhibit incomplete dominance or co-dominance.

Step-by-step solution

The number of phenotypic categories in a dihybrid cross is the product of the number of phenotypic categories produced by each individual gene. When a gene in a heterozygous condition exhibits complete dominance, it produces 2 phenotypes in the F₂ generation (dominant and recessive). When a gene exhibits incomplete dominance or co-dominance, it produces 3 phenotypes in the F₂ generation. Since the total number of phenotypic categories is 9 , and the genes assort independently, this must be the product of 3 3 . Ther

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