(a) Mendel first crossed pure bred tall pea plants with pure bred dwarf pea plants and found that only tall pea plants were produced in the first generation. No dwarf pea plants were obtained in F1 generation. Mendel concluded that the first generation showed the traits of only one of the parent plants; tallness. The trait of other parent plant, dwarfness, did not show up in the progeny of first generation. Mendel then crossed the tall pea plants of the first generation (F Generation) and found that tall plants and dwarf plants were obtained in the second generation (or F generation) in the ratio of 3:1. Mendel noted that the dwarf trait of the parent pea plant which had seemingly disappeared in the first generation progeny reappeared in the second generation. In this way, Mendel’s experiments with tall and dwarf pea plants showed that the traits may be dominant and recessive.
(b) When Mendel crossed pure-bred tall pea plants with pure-bred dwarf pea plants, he found that only tall pea plants were produced in the F generation. When Mendel further crossed the tall pea plants of the F generation, he found that the tall plants and dwarf plants were obtained in the ratio 3:1 in the F generation. Mendel noted that all the pea plants produced in the F generation were either tall or dwarf. There were no plants with intermediate height (or medium height) in-between the tall and dwarf plants. In this way, Mendel’s experiment showed that the traits (like tallness and dwarfness) are inherited independently. This is because if the traits of tallness and dwarfness had blended (or mixed up), then medium sized pea plants would have been produced.
