Ans. Mendel's Law of Segregation
Mendel studied the inheritance of seed shape first. For this purpose, he crossed (reproduced) two plants having one contrasting trait i.e. seed shape, A cross in which only one trait is studied at a time, is called as a monohybrid cross.
Explanation .
Mendel crossed a true-breeding round-seeded plant with a true-breeding wrinkled-seeded plant. All resulting seeds of the next generation were round. Mendel declared the trait "round seeds" as dominant, while "wrinkled seeds" as recessive. The following year, Mendel planted these seeds and allowed the new plants to self-fertilize. As a result, he got 7324 seeds: 5474 round and 1850 wrinkled (3 round: 1 wrinkled). "
P1 generation
The parental generation is denoted as P1 generation.
F1 generation
The offspring of P1 generation are F1 generation (first filial).
F2 generation
The cross in F1 generation produces F2 generation (second filial).
Similarly, when "true-breeding" tall plants were crossed with "true-breeding" short plants, all offspring of F1 were tall plants i.e. tallness was a dominant trait. When members of Ft generation were self-fertilized, Mendel got the ratio of tall to short plants in F2 as 3:1 Figure 15.7
Conclusion
Mendel concluded that the traits under study were controlled by discrete (separable) factors or genes. In each organism, the genes are present in pairs. During gamete formation, the genes (alleles) of each pair segregate from each other and each gamete receives one gene from the pair. When the gametes of male and female parents unite the resulting offspring again gets the genes in pairs. These conclusions were called the Law of Segregation.