This document contains 12 multiple choice questions about genetics concepts such as inheritance patterns, probability of traits being passed on, pedigrees and X-linked disorders. The questions cover topics like dominant vs recessive traits, heterozygous vs homozygous genotypes, and calculating probabilities for traits occurring in offspring based on parental genotypes.

1. QUESTION 1
1. Having hair on the back of the hands is a dominant trait. If
two people who heterozygous for the condition have children,
what is the probability that they will have a child who does
NOT have hair on the back of their hands?
0%
25% or 1/4
50% or 2/4
75% or 3/4
100% or 4/4
8.5 points
QUESTION 2
1. Who is responsible for sex determination in humans?
male
female
6.5 points
QUESTION 3
1. In the pedigree below, all shaded individuals express the
gene in question. For example, Arlene "has" the trait, she
displays the phenotype in question. For example, if we were

2. following the inheritance pattern of a widow's peak, Arlene has
a widow's peak (that is NOT the trait here, just an example).
Unshaded individuals (blank circles and squares) do not
manifest the trait in question, but their specific genotype is
unknown - they could be heterozygous, homozygous dominant,
or homozygous recessive.
2. What is the mechanism of inheritance of this trait?
recessive
dominant
8.5 points
QUESTION 4
1. In the pedigree below, all shaded individuals express the
gene in question. For example, Arlene "has" the trait, she
displays the phenotype in question. For example, if we were
following the inheritance pattern of a widow's peak, Arlene has
a widow's peak (that is NOT the trait here, just an example).
Unshaded individuals (blank circles and squares) do not
manifest the trait in question, but their specific genotype is
unknown - they could be heterozygous, homozygous dominant,
or homozygous recessive.
What is Sam's genotype?
homozygous recessive (hh)
heterozygous (Hh)
homozygous dominant (HH)

3. 8.5 points
QUESTION 5
1. Normally when a person consumes a product that contains
lactose (such as milk or cheese), the body breaks the sugar
lactose down into galactose and glucose. Galactosemia is
disorder caused by a missing or defective enzyme which ends up
causing galactose to accumulate to poisonous and sometimes
deadly levels. Galactosemia is a recessive disorder. If two
individuals are heterozygous for this trait, what is the
probability that their children WILL HAVE galactosemia?
0%
1/4 or 25%
2/4 or 50%
3/4 or 75%
4/4 or 100%
8.5 points
QUESTION 6
1. Huntington's disease is characterized by a late onset of nerve
degeneration that leads to death. The allele that causes the
disease is dominant. Lucille is homozygous dominant for the
disease and Joe is homozygous recessive. What is the
probability that their children will have Huntington's disease?

4. 0%
1/4 or 25%
2/4 or 50%
3/4 or 75%
4/4 or 100%
8.5 points
QUESTION 7
1. Hemophilia, disease in which the blood lacks a clotting
factor, is caused by an X linked recessive gene. Joe doe not
have hemophilia and Lucille is heterozygous for the condition.
What is the chance that their MALE child will have hemophilia?
(Note: you are calculating the probability for their MALE
children only, in other words if they have 1 male child, what is
the probability that he will be born with the disease?)
0%
1/4 or 25%
2/4 or 50%
3/4 or 75%

5. 4/4 or 100%
8.5 points
QUESTION 8
1. In humans, having facial dimples is dominant to not having
facial dimples. Mary has dimples, yet only 3 of her 10 children
have dimples. What must Mary's genotype be?
homozygous dominant
heterozygous
homozygous recessive
has dimples
does not have dimples
8.5 points
QUESTION 9
1. Red-green color blindness is an X-linked recessive disorder.
If Allison is heterozygous (a carrier), and her husband, Michael,
is NOT colorblind. What is the chance that their male children
will be colorblind? (Note: you are calculating the probability
for their MALE children only, in other words if they have 1
male child, what is the probability that he will be born with the
disease?)
0%

6. 25% or 1/4
50% or 2/4
75% or 4/4
100% or 4/4
8.5 points
QUESTION 10
1. Red-green color blindness is an X-linked recessive disorder.
If Allison is heterozygous (a carrier), and her husband, Michael,
is NOT colorblind. What is the chance that their female children
will be colorblind? (Note: you are calculating the probability
for their FEMALE children only, in other words if they have 1
female child, what is the probability that she will be born
colorblind?)
0%
25% or 1/4
50% or 2/4
75% or 3/4
100% or 4/4
8.5 points

7. QUESTION 11
1. Match the term to its best description.
the observable trait expressed by an organism
the genes for a trait present in an organism
the different varieties of a gene for a particular trait
the state of having two identical alleles for a particular trait
A.
homozygous
B.
genotype
C.
phenotype
D.
alleles
QUESTION 12
1. Why do X-linked genetic disorders occur more frequently in
males? Answer in a few short sentences.