High School Biology : Inheritance Patterns

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Codominance And Incomplete Dominance

A sugar flower has white petals, and is homozygous for this trait. Another sugar flower is homozygous for red petals. The white and red sugar flowers are crossed, and produce offspring with pink petals. Which of the following terms describes this type of inheritance?

Possible Answers:

Epistasis

Polygenic inheritance

Incomplete dominance

Codominance

Complete dominance

Correct answer:

Incomplete dominance

Explanation:

Incomplete dominance is described by a phenotype that is not completely dominant over another. Therefore, it will be a "blending" of colors in the case of this question, therefore the petals are pink. Codominance is when both dominant traits are expressed, therefore if white was considered dominant and red was also a dominant trait, the petals would have spots of white and red, with no pink. Polygenic inheritance is described by one characteristic influenced by multiple genes, which is not the case in this problem. Finally, epistasis involves the suppression of genes, however in this problem color is not suppressed.

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