Answer No 1:
The trait which is being studied in the cross is the height of the pea plant.
Answer No 2:
The two alleles for this trait are tall height allele which we can write as T and the allele for short height which we can write as t.
Answer No 3:
The allele for tall height is the dominant allele. We can say this because when a cross between a dominant homozyous and a recessive plant were made the offsprings resulted in the tall plants which is the F1 generation in the figure. As a dominant trait masks the recessive trait, hence we can say that the tall height allele is dominant over the short height allele.
Answer No 4:
The allele for short height t is recessive because as we can see the short height trait is being masked by the tall height trait in the F1 progeny. In F2 progeny, there are more number of tall height plants produced which further prove that short height is the recessive trait.
Answer No 5:
The F1 offsprings will have a dominant tall height allele, T, and a recessive short height allele, t. The dominant allele was inherited from the tall parent and the short height allele, t, was inherited from the recessive parent.
We can say that because the F2 progeny shows some plants to have short heights which is only possible if the F1 generation has heterozygous dominant (Tt) alleles.