Question

In: Biology

In Triskelian cats, in the Blondish Galaxy, black coat color is dominant over grey. Coat color...

In Triskelian cats, in the Blondish Galaxy, black coat color is dominant over grey. Coat color is determined by a single autosomal gene with two alleles:

B = black coat color; b = grey coat color.

The autosomal gene for eye color is hypothesized to assort independently from the gene for coat color. The two alleles are:

R = green eye color; r = blue eye color.

If a green-eyed black female cat whose mother has a grey coat and whose father has blue eyes mates with a blue-eyed grey male cat, use the Chi-Square goodness of fit test to determine whether the following counts of 1000 F1 offspring in Table 1 are consistent with the two-locus mode of inheritance, specifically independent assortment.

The threshold for a significance level of 5% for the Chi-square test with 3 degrees of freedom is 7.8150.

Table 1. Observed counts for two cat phenotypes.

Category Coat Color Eye Color Observed Count
1 Grey Green 155
2 Grey Blue 176
3 Black Green 367
4 Black Blue 302

NOTE: THIS IS A HARD QUESTION. YOU MUST DO SEVERAL CALCULATIONS.

A. REJECT, because the Chi-Square Value is 446.831.

B. REJECT, because the Chi-Square Value is 123.576.

C. REJECT, because the P-Value is 57.224.

D. ACCEPT, because the P-value is 1E-04 < 7.815.

E. REJECT, because the P-value is 1E-04 < 0.05.

Solutions

Expert Solution

Ans:

B. REJECT, because the Chi-Square Value is 123.576.

Explanation: If a green-eyed black female cat whose mother has a grey coat and whose father has blue eyes mates with a blue-eyed grey male cat, green-eyed black, green-eyed blue,blue-eyed black and blue-eyed grey offspring are produced in 1:1:1:1 ratio. The cross is given below-

The calculated chi-square value 123.576 is much higher than the table value 7.8150 at 3 DF (5% probability). The deviation between observed and expected value is not good fit. So, the assumed hypothesis 1:1:1:1 is rejected. This significant deviation is due to faliure of independent assortment.

All other options are incorrect because the calculated chi-square value is 123.576 and the assumed hypothesis is rejected.


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