Question

You are studying two genes in corn that you believe may be linked: seed shape and and kernel color. You cross two true-breeding corn plants (one with red kernels and round seeds to one with yellow kernels and wrinkled seeds) and receive all red- kerneled, round seed offspring. You then perform a test-cross using the F1 offspring and a yellow-kerneled, round seed corn and receive the following result: 610 red kernels, round seeds 90 yellow kernels, round seeds 100 red kernels, wrinkled seeds 200 yellow kernels, wrinkled seeds Total: 1000 F2 kernels You hypothesize that these two corn kernel genes follow simple Mendelian genetics and assort independently. Perform a chi square analysis to test this hypothesis. To receive full points, please state: The O and E values for each phenotypic category examined Degrees of freedom The calculated chi square value Whether or not your null hypothesis is rejected or accepted based on your calculated chi square value. Note that the chi square table has been included below.

Answer 1

Answer:

According to Mendel experiments, dihybrid testcross ratio is 1:1:1:1. It means that each expected progeny is 1000/4=250.

Phenotype	Observed (O)	Expected (E)	(O-E)2	(O-E)2/E
Red, round	610	250	129600	518.4
Yellow, round	90	250	25600	102.4
Red, wrinkled	100	250	22500	90
Yellow, wrinkled	200	250	250	0

Total of (o-e)2 = chi-square value= 710.8

Degrees of freedom = number of Genotypes -1

Df = 4-1=3

Critical value = 7.815

The chi-square value of 710.8 is greater than the critical value of 7.815. hence, the hypothesis is rejected and data is not fit into Hardy-weinberg equilibrium.