Starter:
Incomplete dominance:
Pink snapdragon flowers, the result of a cross between red and white flowers, are an example of incomplete dominance because:
A.
Red pigment protein is produced at low levels
B.
Heterozygotes produce a pink pigment protein
C.
Flowers express both red and white pigments
Codominance:
Blood type is considered a trait that shows codominance because:
A.
Two different alleles are present in the nucleus
B.
Two phenotypes are visible in the organism
C.
The heterozygote is an intermediate phenotype
Multiple Alleles:
A gene can have more than two alleles:
A.
In an individual that has more than two chromosomes
B.
When the gene is present on homologous chromosomes
C.
In a population of individuals
Lecture 19 Page 1

Epistasis:
In epistasis, a heterozygote for gene X:
A.
Produces an intermediate phenotype between the dominant and recessive homozygote
B.
Shows two phenotypes in the offspring
C.
Is only visible if gene Y is expressed
D.
Produces a trait that ranges along a continuum.
Pleiotropy:
An example of pleiotropy is:
A.
Expression of a gene is silenced by another gene
B.
Multiple phenotypes are affected by a single gene
C.
Both alleles produce visible phenotypes
D.
A phenotype is affected by multiple genes
E.
The phenotype is visibly reduced in the heterozygote
Polygenic inheritance:
A gene for skin color mutates and is no longer functional. People with this allele continue to have several different skin tones. This occurs because:
A.
The gene for skin color is codominant
B.
There are multiple genes that affect skin color
C.
Heterozygotes of the skin color gene have an intermediate phenotype
D.
The mutated gene was epistatic to the other skin color genes.
Lecture 19 Page 2

Compare and Contrast:
Find one similar thing and one different thing about two types of inheritance:
Incomplete and Codominance
Codominance and Pleiotropy
Epistasis and polygenic inheritance
Pleiotropy and polygenic inheritance
Polygenic inheritance and multiple alleles
More Practice:
Sixteen alleles are known to exist for a given gene in a diploid organism. This means that any given individual of that species can have:
A.
Up to 16 chromosomes with that gene
B.
Up to 16 genes for that trait
C.
A haploid number of 8 chromosomes
D.
Up to 16 different traits
E.
At most, 2 alleles for that gene
When a brown cow (BB) is crossed with a white cow (WW), the result is a roan cow with some brown and some white hair. This is an example of:
A.
Incomplete dominance
B.
Codominance
C.
Epistasis
If two parents have children of all four blood types, what must the parental phenotypes be?
A.
One is A; one is B
B.
Both are AB
C.
One is AB, one is O
D.
Both are O
Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?
A.
Multiple alleles
B.
Pleiotropy
C.
Epistasis
Lecture 19 Page 3