Concept explainers
E16. A cross was made between a plant that has blue flowers and purpleseeds to a plant with white flowers and green seeds. The following data were obtained:
Total:
Start with the hypothesis that blue flowers and purple seeds aredominant traits and that the two genes assort independently. Calculate a chi square value. What does this value mean with regardto your hypothesis? If you decide to reject your hypothesis, whichaspect of the hypothesis do you think is incorrect (i.e., the ideathat blue flowers and purple seeds are dominant traits, or the ideathat the two genes assort independently)?
To analyze:
A cross between a plant with blue flower and purple seeds with a plant with white flower and green seeds resulted in the following gametes-
Consider the hypothesis that blue flowers and purple seeds are dominant traits, and these two genes assort independently.
From the given information, calculate the chi-square value.
What does the value obtain depict regarding the hypothesis?
Question asked- If you decide to reject your hypothesis, which aspect of the hypothesis do you think is incorrect (i.e., the idea that blue flowers and purple seeds are dominant traits, or the idea that two genes assort independently)?
Introduction:
In genetic crosses, to know whether the data is significant or whether it fits in any of the Mendelian ratios, the Chi-square test
The test is performed in a series of steps-
Explanation of Solution
From the given information, the cross is made between two plants that resulted in the following data:
The hypothesis is that purple seeds and blue flowers are dominant traits, and they assort independently.
In a dihybrid cross, if two heterozygous genes are crossed, the expected phenotypic ratio generally results with the
So, the test statistics
The degree of freedom is the number of phenotypes minus
For
The estimated value is much greater than expected, hence, the hypothesis is rejected.
Hence,
These genes may be found on the same chromosome and do not assort independently.
All the aspects are verified.
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Chapter 2 Solutions
Genetics: Analysis and Principles
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