Name ______________________________________Block _______ Date ________________
Pedigree Problem Set
I
II
1
2
1
2
4
5
= Huntington’s
Disease
3
6
7
8
III
1
2
3
4
5
1. Which members of the family above are afflicted with Huntington’s Disease? ____________________________
2. There are no carriers for Huntington’s Disease- you either have it or you don’t.
With this in mind, is Huntington’s disease caused by a dominant or recessive trait? ___________________
3. How many children did individuals I-1 and I-2 have? _______________________________________________
4. How many girls did II-1 and II-2 have? ___________ How many have Huntington’s Disease? _______________
5. How is individual III-2 and II-4 related? _____________________ I-2 and III-5? _______________________
6. The pedigree to the right shows the passing on
of Hitchhiker’s Thumb in a family. Is this trait
dominant or recessive? ____________________
I
8
1
2
1
2
7. How do you know? ______________________
II
8. How are individuals III-1
and III-2 related? ________________________
9. Name 2 individuals that
have hitchhiker’s thumb. __________________
II
I
3
1
4
2
3
IV
1
10. Name 2 individuals that were
carriers of hitchhiker’s thumb. ______________
2
3
I
11. Is it possible for individual IV-2 to be a carrier? __________
Why? __________________________________
12. The pedigree to the right shows the passing on of
colorblindness. What sex can ONLY be carriers of
colorblindness? __________________________
13. With this in mind, what kind of non-mendelian
trait is colorblindness? ______________________
14. Why does individual IV-7 have colorblindness?
__________________________________________
II
II
I
IV
1
2
3
4
5
6
7
4
15. Why do all the daughters in generation II carry
the colorblind gene? _________________________
16. Name 2 IV generation colorblind males. _________
17. Below is a pedigree of the Brown family. The shaded individuals are color blind. Color blindness is a sexlinked, recessive trait. Fill in the genotype of as many individuals as you can.
18. Construct a pedigree with the following information, and answer the questions at the end. You should considered
brown hair to be dominant and blonde hair to be recessive. (It is really more complicated than this!) You should
shade in those individuals in the pedigree who have blond hair. Be sure to show all genotypes.
Generation I: A man with brown hair marries a woman with blonde hair who is one year older than the man.
Generation II: They have 5 children. The first-born is a girl, who marries a man with blonde hair. The second
and third born are boys with blonde hair. The fourth and fifth born were girls, both with brown hair. The
youngest daughter marries a man with brown hair.
Generation III: The marriage of the oldest daughter from generation II produces 3 girls, all of whom have
blonde hair. The marriage of the youngest daughter from generation II produces 2 boys that are identical twins,
both have blonde hair.
Is it possible for the children in generation 3 to have brown hair?
Label the pedigree with as many genotypes as you can.