Final answer:
A homozygous tall plant (TT) crossed with a homozygous short plant (tt) will result in offspring that are all heterozygous (Tt) and exhibit the tall phenotype.
Step-by-step explanation:
1) The genotype for the tall plant is TT (homozygous dominant).
2) The genotype for the short plant is tt (homozygous recessive).
3) 100% of the offspring is predicted to be heterozygous (Tt) in this particular cross.
4) The only possible phenotype for the offspring is tall, as the dominant allele (T) masks the recessive allele (t).
In genetics, alleles such as T (tall) or t (short) are versions of a gene. A dominant allele like T will express the trait even if only one copy is present, while a recessive allele like t can only express the trait when two copies are present (homozygous recessive). Therefore, two different genotypes, TT (homozygous dominant) and Tt (heterozygous), result in the same phenotype of a tall plant. A homozygous tall plant crossed with a homozygous short plant will always produce heterozygous tall offspring.