This problem illustrates why classical geneticists in the days before DNA analysis usually needed to work with traits showing complete penetrance. Consider sweet peas, where aabb genotypic class produces purple flowers and all other genotypic classes have white flowers. a) If the parental generation is AA bb x aa BB, what phenotypic ratio do you expect in the F2 generation assuming complete penetrance? (answer in first box) b) Suppose that only 75% of aabb individuals have purple flowers (i.e. penetrance of this trait is 75%). What phenotypic ratio do you now expect among the F2 plants? c) What other phenomena (other than incomplete penetrance) could explain the phenotypic ratio that you answered in (b)?

This problem illustrates why classical geneticists in the days before DNA analysis usually needed to work with traits showing complete penetrance. Consider sweet peas, where aabb genotypic class produces purple flowers and all other genotypic classes have white flowers. a) If the parental generation is AA bb x aa BB, what phenotypic ratio do you expect in the F2 generation assuming complete penetrance? (answer in first box) b) Suppose that only 75% of aabb individuals have purple flowers (i.e. penetrance of this trait is 75%). What phenotypic ratio do you now expect among the F2 plants? c) What other phenomena (other than incomplete penetrance) could explain the phenotypic ratio that you answered in (b)?

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Description: How do you solve this phenotypic ratio question? This problem illustrates why classical geneticists in the days before DNA analysisusually needed to work with traits showing complete penetrance. Consider sweetpeas, where aabb genotypic class produces

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter5: The Inheritance Of Complex Traits

Section: Chapter Questions

Problem 5QP: As it turned out, one of the tallest Potsdam Guards had an unquenchable attraction to short women....

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