Question

Uncle Smiley is heterozygus for a yellow face, married a woman with a green face.Both of them always wanted a large family! If they were to have 12 children, what are the probability that the children would have yellow faces? How many would have green faces? Create a Punnett square to help you find your answer

Answer 1

The probability that the children would have yellow faces is ½. Six children would have green faces.

Explanation:

It is given here that uncle smiley is heterozygous for yellow face. If an individual is heterozygous for a trait then it will be the dominant trait that will be expresses. Thus the dominant trait here is yellow face.  

The wife has green face which means that she is homozygous recessive since she expresses the recessive trait. Let the letter Y represent the dominant yellow and letter y represent the recessive trait green. The trait can be represented as  

$Yy \times yy$

Yy                              Yy                                  yy                                      yy

Yellow                  yellow                            green                              green

It is clear from the cross that half of the individuals will have yellow face and half will have green face. Thus if the couple has 12 children the probability that the children have yellow faces will be 1/2.

6 children would have green faces.