Final answer:
In a parental cross between Tt and TT, using a Punnett square shows that 25% of the offspring will have the alleles tt.
Step-by-step explanation:
To calculate the genetic possibilities of the offspring from a parental cross between Tt and TT, we can use a Punnett square. Place the T allele from the TT parent along the top and the T and t alleles from the Tt parent along the side. Fill in the squares by combining one factor from each parent. The Punnett square will show that there are two potential offspring with the tt genotype, representing 25% of the total offspring.