Final answer:
When a heterozygous tall plant is crossed with a purebred tall plant, none of the offspring are likely to be short.
Step-by-step explanation:
In this cross, a heterozygous tall plant (Tt) is crossed with a purebred tall plant (TT). Using a Punnett square, we can determine the possible genotypes and phenotypes of the offspring. The genotype of the heterozygous plant is Tt, where T represents the dominant allele for tallness and t represents the recessive allele for shortness. The genotype of the purebred tall plant is TT.
When the two plants are crossed using a Punnett square, the possible genotypes of the offspring are: TT (tall), Tt (tall), TT (tall), and Tt (tall). This means that all the offspring will have at least one dominant allele for tallness (T), and none of them will have the recessive allele for shortness (t). Therefore, none of the offspring are likely to be short.