Ans. Mendel's Law of Independent Assortment
Mendel studied two contrasting traits at a time. Such crosses are called dihybrid crosses. He performed experiments on two seed traits i.e."Shape and colour
The trait of round seeds (controlled by allele R)was dominant over wrinkled (con rolled by allele r) seeds. Similarly yellow seed colour (controlled by Y) was dominant over green (controlled by y).
Cross
Mendel crossed a true-breeding plant that had round yellow seeds (RRYY) with a true-breeding plant having wrinkled green seeds (rryy). All seeds in F1 generation were round yellow.
Result
When F1 seeds grew into plants, they were self-fertilized, This cross produced seeds with four phenotypes. There were 315 round yellow seeds, 108 round
green seeds, 101 wrinkled yellow seeds and 32 wrinkled green seeds. The of these phenotypes was 9:3:3:1. Figure 15.8
Explanation
Mendel explained that the two traits i.e. seed shape and seed colour are not tied| with each other.The segregation of 'R' and V alleles happens independently of| the segregation of 'Y and R alleles.
From this experiment, Mendel concluded that different traits are inherited independently of one another. This principle is known as the Law Of I independent Assortment. It states as:the alleles of a gene pair segregate (get; separated and distributed to gametes) independently from the alleles of other gene pairs".