What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for both alleles?
A)16/16
B)9/16
C)6/16
D)3/16
E)1/16

Question

Quizplus · Accepted Answer

The cross of Aa Bb with Aa Bb will produce offspring with genotypes of AA, Aa, BB, Bb, AB, and ab, each with a probability of 1/4 (as there are four possible gamete combinations for each parent).

Of these genotypes, only AA (homozygous dominant) and AB (heterozygous dominant for both alleles) will express the dominant trait for both alleles.

Thus, the fraction of the time that the cross will produce an offspring with both dominant traits is the sum of the probabilities of these two genotypes: 1/4 (AA) + 1/4 (AB) = 1/2.

To simplify the fraction, we can convert 1/2 to 8/16, so the answer is 9/16 (the total possible outcomes).

What Fraction of the Time Will the Cross of Aa