What is the ratio if TT and tt are crossed?

When a true-breeding tall plant (TT) is crossed with a true-breeding short plant (tt), all the offspring in the first generation (F1) will be heterozygous (Tt) and exhibit the tall phenotype, as tall (T) is dominant over short (t). Therefore, the phenotypic ratio of the offspring will be 100% tall. If these F1 plants are then crossed with each other (Tt x Tt), the resulting phenotypic ratio in the second generation (F2) will be 3 tall (TT or Tt) to 1 short (tt).