When pure-breeding red four o'clock flowers (Mirabilis jalapa) are crossed with pure-breeding white flowers, all F1 offspring bear pink flowers. What genetic phenomenon does this illustrate?
Answer and explanation
Correct answer: A. incomplete dominance
- Step 1: Incomplete dominance occurs when neither allele is completely dominant over the other. Step 2. The heterozygous genotype (CR CW) expresses an intermediate phenotype (pink) between homozygous red (CR CR) and homozygous white (CW CW). Answer: incomplete dominance (blending of phenotypic expression). Why not the others: Complete dominance would produce only red flowers; epistasis involves interaction between different genes; polygenic traits involve multiple gene loci.
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