Biologists wish to mate pairs of fruit flies having genetic makeup RrCc, indicating that each has one dominant gene (R) and one recessive gene (r) for eye color, along with one dominant (C) and one recessive (c) gene for wing type. Each offspring will receive one gene for each of the two traits from each parent. The following Punnett square shows the possible combinations of genes received by the offspring:

Any offspring receiving an R gene will have red eyes, and any offspring receiving a C gene will have straight wings. So based on this Punnett square, the biologists predict a ratio of 9 red-eyed, straight-winged (x):3 red-eyed, curly-winged (y):3 white-eyed, straight-winged (z):1 white-eyed, curly-winged (w) offspring. To test their hypothesis about the distribution of offspring, the biologists mate a random sample of pairs of fruit flies. Of 200 offspring, 99 had red eyes and straight wings, 42 had red eyes and curly wings, 49 had white eyes and straight wings, and 10 had white eyes and curly wings. Do these data differ significantly from what the biologists have predicted? Carry out a test at the A  0.01 significance level

Short Answer

Expert verified

Yes, these results are dramatically different from what the biologist projected.

Step by step solution

01

Given Information

Given in the question that the possible combinations of genes received by the offspring:

02

Calculate the expected frequencies

The following are the estimated frequencies for the four genetic fruit flies, based on the information provided:

This is the weighted average of the four genetic fruits:9:3:3:1

The following are the predicted frequencies for red-eyes with straight wings.

=916×200=112.50

Then, for the red eyed curly winged and white eyed straight winged, compute the predicted frequencies:

=316×200=37.50

Calculate the white eyed curly winged's predicted frequency:

=116×200=12.50

As a result, here is how the contingency table will look:

ObservedExpectedRed eyed straight winged99112.5Red eyed curly winged4237.5White eyed straight winged4937.5White eyed curly winged1012.5

03

Check the condition 

Now, consider the following conditions:

Random circumstance: It is satisfied since the genetic fruits flies data was chosen at random. It is satisfied because the total offspring are given to be 200, which is a large sample and greater than ten.

Individual kids inherit their qualities independently from one another, satisfying the independent condition. As a result, all of the requirements are met.

Assume the following hypothesis:

H0: The data are same

H1: The data are different

Now compute the chi square as follows:

χ2=(99-112.5)2112.5+(42-37.5)237.5+(49-37.5)237.5+(10-12.5)212.5=6.187

Now, check the degree of freedom:

df=Numberofcategories-1=4-1=3

Therefore, the pvalue will be:

p=0.0129

We shall reject the null hypothesis if the P-value will be less than the significance level.

As a result, we have

P>0.01Not RejectH0

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