d) The Punnett square for the cross between two plants with genotype tt and Tt is shown below:
T | t
--|--
t | Tt
t | tt
t | t
--|--
t | tt
t | tt
e) The genotype ratio for this cross is 1:1 (Tt:tt) as shown in the Punnett square.
f) The phenotype ratio for this cross is 1:1 (tall:short). All the offspring will have short stems because the tt genotype is homozygous recessive and the Tt genotype is heterozygous. The expression of the T allele masks the expression of the t allele in heterozygotes, so the offspring will all have the recessive phenotype.