(a) Explain Mendel's law of independent assortment by taking a suitable example.
(b) How did Morgan show the deviation in inheritance pattern in Drosophila with respect to this law?

Explanation

(a) Independent Assortment : This law states that in the inheritance of two pairs of contrasting characters, the factors of each pair of characters segregate independently of the factors of the other pair of characters. This law was proposed by Mendel based on the result of dihybrid crosses on Pea plants where seed color and seed shape were studied. Mandel obtained a dihybrid cross for round and yellow seeds and wrinkled and green seeds.
He obtained a dihybrid phenotypic ratio of 9 : 3 : : 3: 1.
Morgan carried out dilybrid crosses in drosophila to study genes that showed sex linkage . He hybridised yellow- bodied white eyed females to brown- bodied red eyed males and carried out the study to `F_(2)` and noticed that the `F_(2)` phenotype ratio deviated from the 9 : 3 : 3 : 1 Mendel dihybrid `F_(2)` phonotypic ratio. Morgan used the genes that were both located on x-chromosome and summed up that the proportion of parental gene combinations is much higher than the non-parental one in case of physical association of genes or linkage of two genes.