Explanation

3 : 1 Law of Independent Assortment Mendel also worked with and crossed pea plants that different in two characters/factor. He crossed between pea plant that has seeds with yellow colour and round shape and other that has seeds of green colour and wrinkled shaped. Ratio appeared as 9 : 3 : 3 : 1 such ratio appeared for several character that Mendel studied 9/16 = Yellow round 3/16 = Yellow wrinkled 3/16 = Green yellow 1/16 = Green wrinkled Based on such observation Mendel concluded second law of inheritance called law of independent assortment. According to this principle or law the two factors of each character assort or separate independent of the factors of other characters at the time of gamete formation and get randomly re-arranged in the offspring producing both parental and new combination of traits. Thus, the phenotypic ratio of a dihybrid cross is 9 : 3 : 3 : 1. The occurrence of four types of plants (more than parental types) in the F2 generation of dihybrid cross shows that the factors of each of the two characters assort independent of the others as if the other pair of factors are not present. It can also be proved by studying the individual characters of seed colour and seed texture sepraterly. Seed colour Yellow (9+3 = 12) : Green (3+1 = 4) or 3 : 1 Seed Texture Round (9+3 = 12) : Wrinkled (3+1 = 4) or 3 : 1 The result of each character similar to monohybrid ratio. Generally, the dihybrid cross used to study the independent assortment of genes