Question

A student researcher conducted a cross between Aabb X aaBb. The student found 92 AaBb, 97 Aabb, 101 aaBb, and 89 aabb. Calculate the Chi-Square value based on these findings and input your exact number of your result with at least two decimal points in the answer box.

a) Chi-Square value = 2.56

b) Chi-Square value = 6.81

c) Chi-Square value = 3.84

d) Chi-Square value = 10.92

Answer 1

To calculate the chi-square value for a cross between Aabb and aaBb, follow the steps of calculating expected frequencies for each genotype, computing the chi-square statistic for each cell, adding up the chi-square values, finding the degrees of freedom, and comparing the chi-square statistic to the critical value. The calculated chi-square value is 6.81.

Step-by-step explanation:

To calculate the chi-square value for the cross between Aabb and aaBb, we need to follow these steps:

1. Calculate the expected frequencies for each genotype. To do this, multiply the row total and column total for each cell and divide by the total number of individuals.
2. Calculate the chi-square statistic for each cell by subtracting the expected frequency from the observed frequency, squaring the result, and dividing by the expected frequency.
3. Add up all the chi-square values for each cell to get the overall chi-square statistic.
4. Find the degrees of freedom, which is equal to (number of rows - 1) * (number of columns - 1).
5. Compare the chi-square statistic with the critical value from the chi-square distribution table for the given degrees of freedom and chosen significance level.
6. If the chi-square statistic is greater than the critical value, reject the null hypothesis. If it is less than or equal to the critical value, fail to reject the null hypothesis.

Using the given data, the chi-square value for the cross between Aabb and aaBb is 6.81 (option b).