Question

Which test will be used in order to see whether the observed phenotypic segregation ratio in $F_1$ generation is 3:1 or not when two hybrids are crossed?

• A. $t$-test
• B. $F$-test
• C. $\chi^2$-test
• D. $Z$-test

Hint:

The Chi-square ($\chi^2$) test is the standard non-parametric test used in genetics to confirm if experimental segregation ratios comply with Mendelian inheritance laws.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
When comparing an observed frequency distribution (like phenotypic counts in a genetic cross) with an expected theoretical ratio (such as Mendelian ratios), we test the "goodness-of-fit".

Step 2: Detailed Explanation:
The Chi-square ($\chi^2$) goodness-of-fit test is designed specifically to determine if there is a significant difference between the observed frequencies and the expected frequencies for categorical data.
Here, the expected theoretical segregation ratio is 3:1.
The other tests have different purposes:
- $t$-test: Compares means of one or two groups.
- $F$-test: Compares variances or evaluates overall model significance in regression/ANOVA.
- $Z$-test: Compares means of large samples when population variance is known.
Therefore, the $\chi^2$-test is used to analyze the phenotypic segregation ratio.

Step 3: Final Answer
The correct option is (C).