Given the allele for tall plants (T) is dominant to the allele for short plants (t), describ the phenotypes of the following genotypes. a) Tt

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tjbrewer eNotes educator| Certified Educator

When an Allele is dominant that means that it will show in a phenotype over the recessive Allele, if present, in the genotype.  Since the Allele for tall plants is dominant, it will show in the phenotype, even if a short allele is present.  Thus a genotype of Tt will show tall plants, because the dominant "tall-plant" allele is present. 

If you had Genotype TT, you would also have tall plants.  If you had genotype tt, you would have short plants, since the dominant Tall-plant allele isn't present.