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 how many should be tall?
a. 5
b. 20
c. 10
d. 0
e. 1/2

Option C

Out of the 20 resulting offspring of the test cross, 10 (50%) will be tall.

Explanation:

Let True-breeding tall plant be "TT"

Let short plant be tt

On crossing, all offspring will be "Tt"

Test cross involves the breeding of an individual with a phenotypically recessive individual. The test cross of offspring "Tt" against "tt" will then yield an equal ratio (1:1) of Tt to tt.

Thus, out of the 20 resulting offspring of the test cross, only 10 (50%) will be tall.

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