Self Assessment Question # 4 for Lesson 11

by Dr Jamie Love © 2002 - 2010
Genetics Course

While conducting a survey of a large, extended family, a doctor observed 8 of the men and boys are colorblind and an equal number (8) men and boys are NOT colorblind. In this same family, he finds that only two of the women and girls are colorblind while the remaining 14 women and girls are not colorblind.

It seems the males are more likely to be colorblind. Is there a link between the sex of the person and whether she/he is colorblind?

We will use the chi-square, in the next question, to find out. But first, tell me the expected numbers of normal and colorblind males and females if there is no link between sex and colorblindness. That is, how many of each of these four groups should you expect if there is no link between sex and colorblindness? Answer that question by completing this table. Hint : ask yourself, "How many people in this population are colorblind and how would I distribute that number equally between the two sexes?".

Phenotypes Expected Normal males Colorblind males Normal females Colorblind females Total 32

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