Question

Examine the pedigree in the figure below. The allele for the presence of a white forelock is dominant. The probability of the couple labeled 2 in the pedigree having a child without a white forelock is

Answer 1

Do you have the figure?

Answer 2

well first off, determine if the allele is autosomal, or sex-linked.

Answer 3

I have no idea

Answer 4

okay well it doesnt favor males or females, so it autosomal

Answer 5

Examine the pedigree in the figure below. The allele for the presence of a white forelock is dominant. The probability of the couple labeled 2 in the pedigree having a child without a white forelock is _______ percent.

Answer 6

1 in 4 chance. the father is heterozygous, the mother is as well, and only a homozygous recessive offspring will not exhibit the trait. Say the father is Aa, the mother is Aa, so the possibilities for offspring are AA, Aa, aA, and aa. four possibilities and only one will result in no white forelock. 1/4. 25%

Answer 7

we know the father is hetero because the trait is dominant and he has a mother (the empty circle next to 1) who doesnt exhibit the trait (so she's aa). since he exhibits the trait, he must be Aa. they also have a child already who is unaffected, so that means both parents must have at least one inactive allele, hence why the mother in 2 is hetero.