The allele for cleft chin (C)is dominant to the allele for uncleft chin (c).A male and female who are both heterozygous for cleft chin have a child.What is the chance that this child will have an uncleft chin?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

Question

Quizplus · Accepted Answer

The Punnett square for this cross is:

|  C   |  c   |
|------|------|
|  C   | CC   | Cc   |
|  c   | Cc   | cc   |

As the parents are both heterozygous, they each have one C allele and one c allele. When we cross them, we can see that there is a 25% chance of each offspring receiving two copies of the recessive c allele and therefore displaying an uncleft chin. This corresponds to answer choice B, 25%.

The Allele for Cleft Chin (C)is Dominant to the Allele