A couple is trying to calculate the chance of genetic traits in their potential offspring. From family history, the man presumes he is heterozygous for the height gene via the "tall" allele (T). His partner is short in stature, so she believes she is homozygous for the height gene via the "short" allele (t). Assuming the "tall" allele is completely dominant, what is the chance that their offspring would be tall in stature?
A)25%
B)50%
C)75%
D)100%

Question

A couple is trying to calculate the chance of genetic traits in their potential offspring. From family history, the man presumes he is heterozygous for the height gene via the "tall" allele (T). His partner is short in stature, so she believes she is homozygous for the height gene via the "short" allele (t). Assuming the "tall" allele is completely dominant, what is the chance that their offspring would be tall in stature? 
A)25%
B)50%
C)75%
D)100%

Quizplus · Accepted Answer

Since the man is heterozygous for the height gene, he has one "tall" allele (T) and one "short" allele (t). This means that he can pass on either the "tall" allele or the "short" allele to his offspring. 
The partner, who is short in stature, is homozygous for the "short" allele (tt). This means that she can only pass on the "short" allele to her offspring. 
Since the "tall" allele is completely dominant, if the offspring receives one "tall" allele from the father, then they will be tall in stature. Therefore, there is a 50% chance (or 1 out of 2) that the father will pass on the "tall" allele and a 100% chance that the mother will pass on the "short" allele. 
Using a Punnett square, we can see that there is a 50% chance that the offspring will inherit one "tall" allele and one "short" allele (Tt), which will result in them being tall in stature. Therefore, the answer is B) 50%.

A Couple Is Trying to Calculate the Chance of Genetic