Chapter 4, Problem 30P

Dr. Ara B. Dopsis and Dr. C. Ellie Gans are performing genetic crosses on daisy plants. They self-fertilize a blue- flowered daisy and grow $\text{100}$ progeny plants that consist of 55 blue-flowered plants, $\text{22}$ purple-flowered plants, and $\text{23}$ white-flowered plants. Dr. Dopsis believes this is the result of segregation of two alleles at one locus and that the progeny ratio is $\text{1:2:1}$. Dr. Gans thinks the progeny phenotypes are the result of two epistatic genes and that the ratio is $\text{9:3:4}\text{.}$ The two scientists ask you to resolve their conflict by performing chi-square analysis on the data for both proposed genetic mechanisms. For each proposed mechanism, fill in the values requested on the form the researchers have provided for your analysis.

a. Use the form below to calculate chi square for the $\text{1:2:1}$ hypothesis of Dr. Sophila.

b. Use the form below to calculate chi square for the $\text{9:3:4}\text{.}$ hypothesis of Dr. Gans.

c. What is your conclusion regarding these two genetic hypotheses?

d. Using any of the $\text{100}$ progeny plants, propose a cross that will verify the conclusion you proposed in part (c). Plants may be self-fertilized, or one plant can be crossed to another. What result will be consistent with the $\text{1:2:1}$ hypothesis? What result will be consistent with the $\text{9:3:4}\text{.}$ hypothesis?