Name _______________________________________
Section 7.2 Complex Patterns of Inheritance
Date __________________
Main Ideas:
 Phenotype can depend on interactions of alleles
 Many genes may interact to produce one trait

Vocabulary:
 Incomplete dominance
 Codominance
 Polygenic trait
1. What happens with alleles that show incomplete dominance?
2. Give an example and explain incomplete dominance.
3. We have 3 alleles for eye color; blue, green and brown. There isn’t an allele for hazel eyes. Now that
you have read what incomplete dominance, how could you explain hazel eyes?
4. Explain how beta fish exhibit incomplete dominance. Though our book used B1B2 to represent the
hybrid, I prefer to use a “gg” for green, “bb” for blue and the hybrid would be “gb”.
5. If we were mixing paint colors using black and white paint, if black was dominant over white paint, a
hybrid would be black. If we are talking about incomplete dominance and neither black nor white are
dominant, then what color would we see? _______________
6. What is codominance?
7. What would the black and white paint in #5 look like with codominance? ________________________
8. What are the three alleles for blood type? (Forget the “I” in front of the superscripts). ____, ____ & __
To help you remember how the blood typing alleles are inherited, remember this formula.
A = B > o.
a. A and B are codominant
b. Both A and B are dominant to O
c. O is recessive to both A and B.
9. What type of blood will each of the following have:
a. A allele and A allele? ___________
b. A allele and O allele? ___________
c. A allele and B allele? ___________
d. B allele and B allele? ___________
e. B allele and O allele? ___________
f. O allele and O allele? ___________
10. Looking at hair and eye color, we can see that there aren’t only three shades of eye color or of hair color.
There can be many shades of each. This can be explained by the fact that traits like eye color, hair color,
skin color, body height and build… are all controlled by two or more genes. The term for this is
________________________ inheritance.