Introduction
In the 19th century, an Australian monk by the name Gregor Mendel carried out experiments on garden pea in an attempt to study the concept of inheritance and hybridization. He was keen on a number of contrasting traits that occurred in garden pea such as short and tall, round and wrinkled or color such as yellow and purple. From his experiments, Mendel derived two laws that are used up to date to describe genetic inheritance. His first law was referred to as the law of segregation where homologous alleles segregate during the process of meiosis and his second law was the law of independent assortment where genes coding for different traits are inherited independently of each other.
The objective of this experiment was to examine the different traits exhibited by corn seeds and use them to study Mendelian genetic crosses.
Materials required
The materials required for the dihybrid cross include corn seeds with different colors of yellow and purple and also displaying different seed shapes.
Procedure
First, a table containing all the possible phenotypes that can be obtained from the seeds is prepared. Seeds are then sorted out on the basis of their color and shape and the obtained data recorded adjacent to the respective phenotypes. The procedure is repeated until all the phenotype groups are filled. From the information given, the value of x2 for each experiment can be determined.
Experimental Data
Fill in the tables below with your observed data, calculate the expected result according to your hypothesis. Determine the Χ2 value for each experiment, and use the table of probabilities to accept or reject the null hypotheses.
Dihybrid cross.
Χ2 value in box
Results
Χ2 = _1717____ degrees of freedom: 3_____
Range of probability: ______________
Accept or reject null hypothesis? ___REJECT_______
Discussion
In dihybrid crossing, two alleles are examined at any single time for example the allele for seed color and that for seed shape.
Chi-square test is a mathematical method used to compare the experimental results with the expected value and ascertain whether it supports the null hypothesis or not. If the chi-square value is small the hypothesis is accepted but if the value is large then the hypothesis may be rejected and for this case the null hypothesis was rejected because the X2 value was very large.
Conclusion
Corn plant occurs in a diploid state (2N) and has both the female and male gametes and a large number of F1 generations can arise from individual crossings. Corn plant has been use in Mendelian genetics because it displays a number of traits like different kernel colors and different seed shapes that can be used in Mendelian hereditary experiments.