Download Pedigree Worksheet

Name: _______________________________
Pedigrees and Inherited Disorders
1. Interpreting a pedigree:
a. What does a shaded shape indicate?
b. What does a square mean?
c. What does it mean when a horizontal line connects a square and a
circle?
d. Are children listed above or below parents?
e. How are the offspring ordered?
2. What is an important application of pedigrees?
3. What do genes code for?
4. What are the two possible outcomes of an allele that causes a genetic disorder?
5. When are recessively inherited disorders evident?
6. What is a carrier?
7. What is the genotypic ratio of offspring from a monohybrid cross (Aa x Aa)?
a. In the
i.
ii.
iii.
b. In the
i.
ii.
iii.
case of recessively inherited disorders…
What fraction of the offspring will likely have a normal phenotype?
What fraction of the offspring will probably be carriers?
What fraction of the offspring will likely be affected with the
disorder?
case of dominantly inherited disorders…
What fraction of the offspring will likely have a normal phenotype?
What fraction of the offspring will probably be carriers?
What fraction of the offspring will likely be affected with the
disorder?
8. If a set of parents have the genotypes Aa x aa, for a recessively inherited
disease…
a. What is the likelihood that their children will inherit the disease?
b. What is the likelihood that their children will be carriers?
9. For the following disorders, answer: 1) What causes them? 2) Are they
dominantly/recessively inherited? 3) What is the result/phenotype?
a. Cystic Fibrosis
i. _________________________________________________________________
ii. _________________________________________________________________
iii. _________________________________________________________________
b. Sickle-cell Disease
i. _________________________________________________________________
ii. _________________________________________________________________
iii. _________________________________________________________________
c. Achondroplasia
i. _________________________________________________________________
ii. _________________________________________________________________
iii. _________________________________________________________________
d. Huntington’s disease
i. _________________________________________________________________
ii. _________________________________________________________________
iii. _________________________________________________________________
10. Other than the fact that society frowns upon the marriage of close relatives
(siblings/cousins), why is it a bad idea?
11. What does “multifactorial” mean?
a. What is an example of a disorder that is multifactorial?
b. What 4 habits are able to reduce the risk of some multifactorial
disorders?
12. List the 4 options for fetal testing discussed in the chapter.
a. ______________________________________
b. ______________________________________
c. ______________________________________
d. ______________________________________
13. What are some problems that can result from performing these tests?
14. What is the primary purpose of these tests?
15. Is it ever right to abort? Why?
For the following pedigrees, label each individual as AA, Aa, or aa. Then write
“Recessive” if the disease is recessively inherited, or “Dominant” if the disease is
dominantly inherited.