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PCAT Biological Processes – Inheritance Pattern in Flowers

Crossing red with white flowers can result in an intermediate phenotype of pink flowers. This pattern of inheritance is most consistent with:

A. incomplete dominance.
B. codominance.
C. expressivity.
D. epigenetics.

Click or Explanation

A is correct. Incomplete dominance is a form of inheritance in which neither allele is completely expressed over the other. This results in an intermediate phenotype for heterozygotes. Choice B, codominance, refers to a pattern in which both alleles are fully expressed (for example, the A and B alleles in the ABO blood typing system). Expressivity (Choice C) refers to the degree to which a given phenotype is expressed, and epigenetics (Choice D) refers to modifications to gene expression.

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