Question

Suppose that a geneticist discovers a new mutation in Drosophila melanogaster that causes the flies to shake and quiver. She calls this mutation quiver, qu, and determines that it is due to an autosomal recessive gene. She wants to determine whether the gene encoding quiver is linked to the recessive gene for vestigial wings, vg. She crosses a fly homozygous for quiver and vestigial traits with a fly homozygous for the wild-type traits, and then uses the resulting F1 females in a testcross. She obtains the flies from this testcross. Phenotype Number of flies ugt qut 230 vg qu 224 vg qu+ vg+ qu 99 97 Test the hypothesis that the genes quiver and vestigial assort independently by calculating the chi-squared, XP, for this hypothesis. Provide the Xto one decimal place. x2 = Does the X2 value support the hypothesis that the quiver and vestigial genes assort independently? Why or why not? Use the partial table of critical values for X2 calculations to test this hypothesis. No, the X2 = value indicates that the observed progeny are significantly different from what would be expected with independent assortment of the two genes. No, the X2 = value indicates that there are too many phenotypes for independent assortment. Yes, the X2 = value indicates that the genes vestigial and quiver assort independently. Yes, the X2 = value indicates that the observed and expected number of progeny are equal in number.

Answer 1

When there is found independent assortment, then the each progeny are found in 1/4 proportions of total. 1/4×(650)=162.5

Chi square table:

Phenotype	observed flies (O)	Expected flies (E)	(O-E)^2/E
vg+ qu+	230	162.5	28.03846
vg qu	224	162.5	23.2753846
vg qu+	97	162.5	26.4015385
vg+ qu	99	162.5	24.8138462
Total	650	650	102.5292

The answer upto one decimal place is 102.5

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The chi square vakue from chi square table at degree of freedom n-1=4-1=3 and at p =0.05 is 7.815

As our chi square experimental value is more tham chi square value from table.

That's why answer is:

No, the X^2 = value indicates that the observed progeny are significantly different from what would be expected with independent assortment of genes.