Question

A plant can have either tall (T) stems or short (t) stems. Two plants are crossed. One has the genotype Tt and the other has the genotype Tt. Fill in the Punnett square below for this cross. (1 point)T t T TT Tt t Tt tt this square has a ratio of 1:2:1.

b) What is the genotype ratio for this cross? (1 point)

c) What is the phenotype ratio for this cross? (1 point)

Answer 1

a) 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

The genotype ratio for this cross is 1:2:1 (TT:Tt:tt) as shown in the Punnett square.

b) The genotype ratio for this cross is 1:2:1 (TT:Tt:tt) as shown in the Punnett square.

c) The phenotype ratio for this cross is 3:1 (tall:short). This is because the T allele is dominant and masks the expression of the t allele in heterozygotes. Therefore, 3/4 of the offspring will have tall stems and 1/4 will have short stems.