Epistasis: Definition & Examples


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question 1 of 3

You perform a dihybrid cross with two mice that are heterozygous for two genes and notice that the offspring are three different colors. The F1 generation mice were pure-breeding brown and black, but the F2 offspring are black, brown, and white. How can this result be explained?

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1. Epistasis is when two or more genes contribute to a phenotype. However, this does not include when the products of two genes contribute _____.

2. Which of the following phenotypic ratios does NOT indicate epistasis in a dihybrid cross?

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About This Quiz & Worksheet

Sometimes multiple genes contribute to a phenotype and this quiz/worksheet combo will help you test your understanding of this concept, called epistasis. Some things you'll be assessed on include the phenotypic ratios and consequences of epistasis.

Quiz & Worksheet Goals

In these assessments you'll be tested on:

  • How epistasis can affect coat color in mice
  • The ways epistatic genes can contribute to phenotypes
  • Phenotypic ratios indicative of epistasis
  • How to determine if epistasis has occurred

Skills Practiced

This quiz/worksheet allows students to test the following skills:

  • Reading comprehension - ensure that you draw the most important information from the related lesson on epistasis
  • Making connections - use understanding of phenotypic ratios and epistatic contribution to predict phenotypic outcomes
  • Problem solving - use acquired knowledge to solve genetic problems
  • Defining key concepts - ensure that you can accurately define epistasis and its related vocabulary

Additional Learning

To learn more about this topic, review the accompanying lesson called Epistasis: Definition & Examples. This lesson covers the following objectives:

  • Define epistasis
  • Use Punnett squares and phenotypic ratios to solve genetic problems involving epistasis
  • Recognize the different epistatic ways that genes can contribute to the same phenotype
  • Differentiate between epistatic and additive contributions to phenotypes