In corn the recessive p allele leads to mutant purplecolored

In corn, the recessive p allele leads to mutant purple-colored seeds (while the dominant P allele produces wildtype yellow seeds). At another locus, the recessive w allele produces a wrinkled seed texture, and the dominant W allele produces smooth seeds. A cross between two Pp Ww individuals yields the following progeny counts: 79 wildtype, 29 with wrinkled seeds of normal color, 21 with smooth purple seeds, and 15 with both mutant phenotypes. Are these numbers consistent with the 9: 3:3:1 ratio that would be predicted if the traits follow Mendel\'s rules? (Use a x^2-test and show all your working. Give the -statistic, the degrees of freedom, the P-value [see slide from lecture notes, and a clear statement describing whether the data is, or is not consistent with the prediction.) x^2-statistic (2 decimal places) d.f. p-value(0.05) Consistent with predicted Mendelian ratio?

Solution

Answer:

X^2 statistics= 5.53

Degrees of freedom (df) = 4-1 = 3

p-value = 5.53

The critical value of chi-square for p=0.05 with 3 d.f. is 7.815. So the p-value (5.53) is less than 0.05 value (7.815)

the statement describing the data is consistent with the prediction

Phenotype	Observed(O)	Expected (E)	O-E	(O-E)2	(O-E)2/E
Wild type	79	81	-2	4.00	0.05
Wrinkled seeds with normal color	29	27	2	4.00	0.15
smooth purlple seeds	21	27	-6	36.00	1.33
both mutant phenotypes	15	9	6	36.00	4.00
	144	144			5.53
	Chi-square vale = 5.53