The answer is 50%. Mendel found that if true breeding Tall plants are crossed with trues breeding short plants, all the next generation of plants, called F1 generation will all be tall. He also showed that if the F1 plants are self pollinated they produce an F2 generation with 3/4 of the plants tall and 1/4 short. Among the 3/4 plants that are tall, 1/4 is homozygous (TT) and 1/2 is heterozygous (Tt)
