Question

Question 55 The next three questions go together. A population of wookiees is polymorphic for fur color, which is controlled by two loci. 168 have black hair, 80 have brown hair, and 88 have yellow hair. You suspect that epistatic interactions between the two loci are responsible for this ratio and wish to test that hypothesis using a x2 test. What is the most likely mode of epistasis? [Select] : brown What are the expected ratios of black [Select] [Select) :yellow Select) furred wookiees?

Answer 1

The type of epistasis that is being followed in this cross is the recessive epistasis as two of the phenotypes are almost equal and hence the ratio will be 9:3:4. The expected ratios of black is 9, brown is 3 and yellow is 4 for the furred wookies.

The chi square for this phenotypes observed is calculated in the following table:

Fur	Observed value	expected	o-e	(o-e)2	(o-e)2/e
Black	168	189	-21	441	2.33
Brown	80	63	17	289	4.59
Yellow	88	84	4	16	0.19
Total	336	336			Chi square= 7.11

Hence the chi square value from this data is 7.11.

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