Question

What is the most likely goestypes of the F1 parents? Using a chi-square test, compare the observed numbers of progerry with those expected from the cross. What conclusions can you draw from the chi-square test. Explain biologically what the chi-square test is telling you about this cross? From the chi-squared test I conclude that these offspring ratios are not correlating to the given geno types of the F1 parents. Therefore I reject the counts of the offsprings present There could be also a huge cultier in the data.

Answer 1

a. Most likely genotypes of F1 parents : BbRr x bbrr

                                                        Offspring : BbRr : Bbrr : bbRr: bbrr (1:1:1:1)

b. Chi square test

Phenotype	Observed (O)	Expected (E)	(O-E)2/E
Black rough	24	19.5	(24-19.5)2/19.5 =1.04
Black smooth	26	19.5	=2.17
White rough	23	19.5	=0.63
White smooth	5	19.5	=10.78
Total	78	78	14.62

Degrees of freedom = 4 – 1 = 3. The chi-square value falls below 12.838 for a probability value less than .005 or 0.5 % that random chance produced the observed ratio of guinea pigs.

c. From the chi-square value, we can see that it is unlikely that random variations produced the observed ratio. Some other phenomena must be acting.