Question

Tall plants are dominant over short plants. one parent is homozygous dominant and the other is heterozygous for plant height. which would most likely be the resulting phenotype of the offspring?

Answer 1

The offspring would be 50% BB and 50% Bb, so the plants would be tall. :)

Answer 2

If the tall plants are dominant over short plants, then a cross between a homozygous and a heterozygous parent will be represented as under:-

 

             TT  x  Tt    

                   |

          TT  Tt  TT  Tt

It is clear from above that 2 types of progenies will be obtained with equal probability i.e. out of four off-springs 50 % will have homozygous dominant (TT) genotype whereas 50% will be heterozygous dominant (Tt).

Also, though genotypically 50% off-springs will have one kind of genotype & 50% off-prings will have another kind of genotype yet phenotypically they all will be tall. It happens because of the presence of T allele (dominant allele) in all the off-springs.