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

Question

Quizplus · Accepted Answer

The cross Aa Bb x Aa Bb results in a 9:3:3:1 phenotypic ratio. The dominant trait for one allele (Aa or Bb) is expressed in 9 (both dominant) + 3 (dominant Aa, recessive Bb) + 3 (recessive Aa, dominant Bb) = 15 out of 16 cases. However, the question asks for expressing the dominant trait for only one of the two alleles, which is 3 (dominant Aa, recessive Bb) + 3 (recessive Aa, dominant Bb) = 6 out of 16 cases.

What Fraction of the Time Will the Cross of Aa