Explain
What is the principle of independent assortment and how is this principle demonstrated in the results of Mendel's dihybrid crosses?
The principle of independent assortment, also known as the law of independent assortment, is one of the fundamental principles in Mendelian genetics. It states that during the formation of gametes (reproductive cells), the segregation (separation) of alleles for one trait is independent of the segregation of alleles for another trait.
This means that the inheritance of one trait does not influence the inheritance of another trait. Each pair of alleles segregates independently of other pairs during gamete formation.
Mendel's dihybrid crosses serve as a demonstration of the principle of independent assortment. In these crosses, Mendel studied the inheritance of two different traits at the same time, such as seed color (yellow or green) and seed texture (smooth or wrinkled).
When Mendel crossed true-breeding plants that differed in both traits (one parent with yellow smooth seeds and the other parent with green wrinkled seeds), he observed that the offspring displayed a 9:3:3:1 phenotypic ratio in the second generation.
This ratio represents the different combinations of traits resulting from independent assortment. Out of every 16 offspring, 9 would have yellow smooth seeds, 3 would have yellow wrinkled seeds, 3 would have green smooth seeds, and 1 would have green wrinkled seeds.
This result demonstrated that the inheritance of seed color was independent of the inheritance of seed texture. Each of these traits followed the principles of Mendelian inheritance, as determined by the independent assortment of alleles during gamete formation.