Answer: Tt will be tall phenotypically, TT will be tall phenotypically, tt will be short phenotypically.
Explanation: From the information provided above, T stands for tall pea plant. This indicates that T is dominant because dominant alleles are written in upper cases. t stands for short pea plant. This indicates that t is recessive because recessive alleles are usually written in lower cases.
A dominant allele has the ability to express itself in the presence of a recessive allele, it masks the effect of a recessive allele. A dominant allele will express itself both in a homozygous and heterozygous state. A recessive allele do not have the ability to express itself in the presence of a dominant allele, its effect is masked by a dominant allele. A recessive allele can only express itself in a homozygous state.
Therefore, T will express itself as tall pea plant both in Tt and TT while t will express itself as short pea plant in tt.