Sexual Reproduction Advantages

Conclusion:

Organisms that use sexual reproduction have an advantage over those that reproduce without genetic exchange. The wide range of off possible offspring offer more abilities and strategies for survival in the ever changing environment. Errors that can occur when copying the parent's genes are reduced to one or two offspring as opposed to all of the offspring. Genes can spread faster form one part of a population to another and introduce positive mutations.

The results obtained from the Wisconsin fast plant experiment were significantly different from the results that Gregor Mendel obtained. The hypothesis was that the Wisconsin fast plant would exhibit a Mendelian like ratio between the dominant phenotypes and genotypes. The number of F2 plants expressing the mutant phenotype of green stem with green leaves was three times the number of F2 plants expressing the homozygous dominant phenotype of purple stem with green leaves. The results for the F2 plants expressing purple stem with yellow-green leaves and green stem with yellow-green leaves matched the hypothesized and expected Mendelian ratios.

The Chi square test showed that the observed ratios did not fit the statistical ratios because the deviation of the observed numbers was extremely greater than the expected numbers. To accept the deviation in the test with three degrees of freedom, the Chi square number needed to be smaller than 7.815 to have a less than five percent chance of occurrence. Our results were greater than five percent with a Chi square number of 113.96.

Because the ratio of dominant phenotypes to the recessive phenotypes was only partially comparable to the statistical Mendelian ratios, and the Chi square number was very large the hypothesis was rejected.

Performing an accurate test cross could indicate independent assortment or linkage between the two traits for stem color and leaf color [1]. This test would cross a plant with dominant purple stem and green leaf phenotype, from the F1 generation of the Wisconsin Fast plants, with a homozygous recessive plant (green stem and yellow-green leaves).

References

1. Peter J. Bowler (1989). The Mendelian Revolution: The Emergence of Hereditarian Concepts in Modern Science and Society. Baltimore: Johns Hopkins University Press.

2. Good, IJ (1973). "What Are Degrees of Freedom?". The American Statistician (The American Statistician, Vol. 27, No. 5) 27 (5): 227-228. doi:10.2307/3087407. http://jstor.org/stable/3087407.

3. Henig, Robin Marantz (2009). The Monk in the Garden : The Lost and Found Genius of Gregor Mendel, the Father of Modern Genetics. Houghton Mifflin. ISBN 0-395-97765-7.

4. "Dihybrid