(a) When Mendel cross pollinated pure tall pea plants with pure dwarf pea plants, only tall plants were obtained in F1 generation in 3:1 ratio. Thus appearence of tall character in both F1 and F2 shows that it is a dominant character. The absence of dwarf in F1 generation reappears in F2 shows dwarfness in the recessive character.
(b) When Mendel conducted a dihybrid cross having two sets of characters, he obtained only one set of parental characters in F1 generation where as in F2 generation he obtained both the set of parental characters as 9:3:3:1 ratio. Thus appearance of new generation or recombinants in the F2 generation along with parental type shows that traits are inherited independently.