Question

In garden peas, the allele for tall plants is dominant over the allele for short plants. A true-breeding tall plant is crossed with a short plant, and one of their offspring is test crossed. Out of 20 offspring resulting from the test cross, about _______ should be tall[A] 0[B] 5[C] 10[D] 15[E] 20

Answer 1

The correct option is C)10

The punnet square for the parent cross is shown below:

t t

T Tt Tt

T Tt Tt

The punnet square for the test cross is shown below

t t

T Tt Tt

t tt tt

As 50% of the offsprings will be dominant. Hence, out of 20, 10 will be tall.