In order to obtain the `F_(1)`-generation Mendel pollinated a pure-breeding tall plant with a pure-breeding dwarf plant. But for getting the `F_(2)`-generatin, he simply self-pollinated the tall `F_(1)` plants. Why?

Explanation

Characters segregate during gamete formation. Pure-breeding parents guve ruse to `F_(1)` with hetoeozyous conditions. Only self-pollination of heterzygotes can result in all possible recombination of characters in progeny as mating is random.