Question

Describe the steps of procedure of Mendel's experiments with suitable example.

Answer 1

Mendel performed monohybrid and dihybrid crosses using the pea (Pisum sativum) plant. In the first monohybrid experiment, he selected homozygous tall plant and a homozygous dwarf plant. The plants were crossed fertilized using the technique of emasculation and bagging. The seeds thus obtained gave rise to the hybrid tall plants (heterozygous) that were called the F${}_1$ generation. In the continuation of the experiment, the F${}_1$ plants were allowed to self-fertilize, and the resultant seeds gave rise to the F${}_2$ generation in which, there were 3 tall plants and 1 dwarf plant phenotypically and 1:2:1 ratio as per their genotype.

In the second experiment, a dihybrid cross was performed. The parent plants were homozygous for yellow and round seeds and green and wrinkled seeds. Emasculation and bagging were performed and cross-fertilization was done. The resultant F${}_1$ progeny was heterozygous with yellow and round seeds. These were then allowed to undergo self-fertilization and 16 offspring were obtained in F${}_2$ as 9 with yellow and round seeds; 3 with yellow and wrinkled seeds' 3 with green and round seeds; and 1 with green and wrinkled seeds.