Mendel was the father of genetics.

The Mendel's laws of inheritance are:- 

(a) Law of Dominance: In Mendel's pea plant breeding experiment, it was found that the hybrid plants showed only one of the contrasting characters. All the plants were tall in the F1 generation. Hence Mendel called tallness, the dominant and dwarfness the recessive character. According to Mendel, a character that represents in the hybrid is called dominant and the one that fails to express is called recessive. In the F1 generation, the recessive characters are present but remained hidden. The character that expresses itself in the F1 generation is termed dominant. On the other hand the character that remains hidden or suppressed in the F1 generation is called recessive. Thus tallness is dominant and dwarfness is recessive.

(b) Law of Segregation: In Mendel's pea plant experiment, it was observed that when the cross- bred pea plant of F1 generation are allowed to cross, they exhibited both tall and dwarf characters had been out of sight for some time but it was not lost or altered permanently. In the F2 generation, dwarf plants appeared again. This clearly indicates that this character of dwarfness had been transmitted through the tall plant of F1 generation. When the dwarf plants were allowed to self-fertilise they produce only dwarf varieties. Thus it is clear that through the dwarfness had been suppressed by the tallness in the F1 generation, yet its characters remained unaltered. In other words, both tallness and dwarfness remained together without contaminating or diluting each other. This indicates that characters are independent of one another.

(c) Purity of Gametes: A gamete has one or the other of a pair of allelomorphs. Therefore, a gamete may carry only the gene for tallness or dwarfness, but it cannot carry both. Thus in Mendel's experiment a gamete carried either the gene for tallness or dwarfness, not both the genes. It further implies that the two types of gametes, T (tall) type and t (dwarf) type, will be produced in equal numbers. An important implication of this law is that a gamete is always pure for a character and never a hybrid. This is called the purity of gametes which forms the bulk of Mendel's lavish discovery. 

When two gametes fuse together the resulting zygote will have both the genes for tallness and dwarfness. Although tallness only expressed itself in the F1 generation, genes for both T type and t type were present in the zygotes. In the long run the characters were segregated when the two gametes were formed. It is evident by the offsprings of the F2 generation where segregation of characters was perceived in the ratio of 1:2:1, i.e. 1/4 pure talls, 1/2 impure talls and 1/4 pure dwarfs. In this way purity of gametes is maintained because of segregation of characters.