Question

If an allele for tall (T) is dominant to an allele for short (t), what proportion of the progeny will be tall in the following cross: Tt x TT?

a. 0/4
b. 1/4
c. 2/4
d. 3/4
e. 4/4

Answer 1

Considering a Tt x TT cross, all offspring will receive at least one dominant T allele, resulting in 100% tall progeny.

Step-by-step explanation:

When considering the cross Tt x TT, we are looking at a parent that is heterozygous for the tall trait (Tt) and a parent that is homozygous dominant (TT). By setting up a Punnett square, we can predict the genotypic ratio of the progeny. Each progeny will receive one allele from each parent, so the possible combinations for the offspring are TT, Tt, and TT (no tt as the TT parent can only give a T allele). Since the T allele is dominant, all of these combinations will result in tall plants. Therefore, the proportion of tall progeny will be 4/4 or 100% tall.