Genetics
Use the information below to answer the following four questions.
Sickle cell anemia is an autosomal recessive genetic disorder that affects thousands of people in the United
States and millions worldwide. Sickle cell anemia commonly occurs in groups whose ancestors came from
Africa, as well as South America, Cuba, Central America, Saudi Arabia, India and the Mediterranean.
Sickle cell anemia is caused by a change in the hemoglobin protein in red blood cells. Sickle cell anemia results
in paleness, fatigue, shortness in breath, and increased heart rate due to a deficiency in the oxygen-carrying
component of the blood. When oxygen levels are low in an affected individual, the red blood cells become
deformed into a curved, sickle shape. People with sickle cell anemia and experience swelling, pain, infection,
and organ damage.
All individuals have to alleles for the gene that codes for the hemoglobin protein (Hb). Individuals with two Hb
A alleles have normal, round red blood cells. Heterozygous individuals, with one Hb A Allele and one Hb S
allele, do not experience symptoms of this disease, but they may produce some sickle0shaped red blood cells.
Individuals with two Hb S alleles have sickle cell anemia.
The diagrams below represent some of the steps in the formation of hemoglobin in two individuals, Y and Z. In
the diagrams, only a small part of the hemoglobin gene sequence is represented.
Individual Y has two Hb A alleles and therefore produces normal red blood cells. Individual Z has two Hb S
alleles and therefore produces sickle-shaped red blood cells.
Which of the following statements best describes why the change in only one DNA base of the hemoglobin
gene results in a different protein product of the gene?
A. The change prevents mRNA from being made.
B. The change alters the amino acid sequence of the protein.
C. The change causes the blood cells to divide in a uncontrolled way.
D. The change creates a second strand of mRNA for each RNA molecule.
2. Which of the following cell structures carries out the process represented by the arrows labeled “2” in the
diagrams?
A. Mitochondrion
B. Nucleus
C. Ribosome
D. Vacuole
3. Which of the following statements best summarizes a change that is represented by the arrows labeled “3”
in the diagrams?
A. A nucleus is formed in each cell.
B. Each cell divides to form two daughter cells.
C. A chain of amino acids is folded to form a protein in each cell.
D. Proteins are transported through the plasma membrane of each cell.
4. Which of the following statements best compares individual Y and individual Z in terms of genotype and
phenotype?
A. The individuals have the same genotype and phenotype.
B. The individuals have the same genotype but different phenotypes.
C. The individuals have different genotypes but the same phenotype.
D. The individuals have different genotypes and phenotypes.
5. An inherited metabolic disorder called phenylketonuria (PKU) can result in serious problems in infancy.
The chance that two parents who are heterozygous will have a child with PKU is 25%. Which of the
following terms best applies to the inheritance pattern for PKU?
A. Codominant
B. Dominant
C. Recessive
D. Sex-linked
6. Which of the following terms applies to traits, such as human eye color, that are controlled by more than
one gene?
a.
b.
c.
d.
co-dominate
polygenic
recessive
sex-linked
7. In pigeons, allele B produces ash-red feathers. The allele b produces blue feathers. The B allele is dominant
to the b allele. A pigeon with genotype Bb is crossed with a pigeon with genotype bb. What percent of the
offspring are expected to have ash-red feathers?
a.
b.
c.
d.
0%
25%
50%
100%
8.
In humans, freckles are encoded by a dominant allele. An individual woman is heterozygous for
freckles.According to the law of segregation, which of the following would apply to a child of this
woman?
a. The child must inherit the dominate allele for freckles
b. The child must inherit the recessive allele for freckles
c. The child has an equal chance of inheriting the dominate allele or the recessive allele for freckles
from her mother.
d. The child has a greater chance of inheriting the dominate allele than the recessive allele for freckles
from her mother.
9.
In pea plants, the allele for purple flowers (P) is dominant to the allele for white flowers (p).
A plant that is heterozygous for purple flowers is crossed with a plant with white flowers. What
percentage of the offspring plants are expected to have purple flowers?
a.
b.
c.
d.
10.
Hemophilia is an X-linked recessive condition in which blood does not clot properly. Queen Victoria of
England had one allele for hemophilia. Which of the following statements describes the most likely
pattern for the occurrence of hemophilia in Queen Victoria’s descendants?
a.
b.
c.
d.
11.
All of Queen Victoria’s children had hemophilia.
All of Queen Victoria’s children were carriers for hemophilia.
Female descendants of Queen Victoria could not pass on the gene for hemophilia.
More male descendants than female descendants of Queen Victoria had hemophilia.
In pea plants, the genes used for seed color and seed shape are on different chromosomes. Which of the
following explains why the genes for these traits are not inherited together?
a.
b.
c.
d.
12.
25%
50%
75%
100%
natural selection
artificial selection
the law of segregation
the law of independent assortment
A pedigree showing the inheritance of a gold dorsal stripe pattern in ball pythons in shown below.
According to the pedigree, what type of trait is this stripe pattern in ball pythons?
a.
b.
c.
d.
13.
A hereditary muscular disease in horses
causes abnormal opening and closing of
the sodium ion channels in the muscle
cells. Which of the following statements
describes the most likely origin of this
disease?
a.
b.
c.
d.
14.
A virus evolved specifically to attack the muscle cells of horses.
Motor neurons near some of the muscle cells degenerated over time.
High levels of sodium in the blood irreversibly damaged the ion channels.
A mutation occurred in the gene coding for the sodium ion channel protein.
In rabbits, a single gene controlling coat color has four alleles. The inheritance pattern for coat color in
rabbits is therefore best described as which of the following?
a.
b.
c.
d.
15.
Co-dominate
polygenic
recessive
sex-linked
Multiple allele
Polygenic
Recessive
Sex-linked
Two chromosome pairs from a diploid organism are shown below. Assuming meiosis and fertilization
occur normally, which of the following pairs of alleles can an offspring receive from this parent?
a.
b.
c.
d.
A and A
A and a
A and f
F and F
16. Below is a pedigree of Duchenne muscular dystrophy (DMD).
Shaded squares and circles represent the disease being expressed. The dots in the circles and squares
represent carriers of DMD. The line through the circles and squares represents death. What type of
disease is this?
A.
B.
C.
D.
Autosomal dominant
Autsomal recessive
Sex Linked
Acquired
17. Vestigial wings on a fruit fly is an autosomal recessive trait showing that the wings are so small they do
not function. White eyes in a fruit fly is a sex linked trait. Determine the answers to the question below.
What is the genotype of the parents if 50% of the females have white eyes and 50% of the males have
white eyes?
a.
b.
c.
d.
e.
Mom is XwXwand father is XwYw
Mom is XXand father is XwY
Mom is XwXand father is XwY
Mom is XwXwand father is XY
Mom is XXwand father is XYw
18. Based off of information from Question 64, what is the genotype of the parents if 75% of the offspring
have vestigial wings?
a.
b.
c.
d.
NN x Nn
Nn x nn
nn x nn
Nn x Nn
19. PKU is an Autosomal recessive trait that affects all races. Affected individuals have a mutated enzyme that
prevents the breakdown of the amino acid phenylalanine. If two parents are carriers for having the trait,
what are the chances of their child having PKU? How many will be carriers?
A.
B.
C.
D.
25% will have PKU, 50% will be carriers, 25% will not carry the trait
50% will have PKU, 50% will be carriers
75% will have PKU, 25% will be carriers
100% will have PKU, none will be carriers
20. From the pedigree below indicate if the trait is Autosomal recessive, Autosomal dominant, or sex linked,
incomplete dominance.
A.
B.
C.
D.
Recessive
Sex Linked
Incomplete dominance
dominant
The picture to the right clearly shows two guinea pigs in love.
Short hair is dominant to long hair. The male is long haired (ss) and
the female is (SS). SS x ss
21. How many of their offspring will be long haired?
A. 25%
B. 50%
C. 75%
D. 100%
E. 0%
22. If the female was Ss x and the male was ss, how many offspring will be long haired?
A.
B.
C.
D.
E.
25%
50%
75%
100%
0%
23. A checkered chicken is a chicken that has ½ of its feathers black and ½ of its feathers white. What does
this indicate?
A.
B.
C.
D.
Incomplete dominance
Sex-linked
Co-dominance
Autosomal Recessive
24. In snap dragon flowers, the genotype is RR for red flower, WW for a white flower and RW for a pink
flower. What does the pink flower indicate about the trait?
A.
B.
C.
D.
Incomplete dominance
Sex-linked
Co-dominance
Autosomal Recessive
25. In snap dragon flowers, the genotype is RR for red flower, WW for a white flower and RW for a pink
flower. What are the phenotypes of the offspring if you cross two pink snap dragons?
A.
B.
C.
D.
25% red, 25% white, 50% pink
75% red, 25% white, 0% pink
25% red, 50% white, 25% pink
0% red, 25% white, 50% pink
26. From the genetic diseases listed below, determine which disorder matches the disease
Down Syndrome
A.
B.
C.
D.
Turner’s Syndrome
Trisomy 21 = Down Syndrome,
Trisomy 21 = Turner’s Syndrome
Trisomy 21 = DNA mutation
Trisomy 21 = Turner’s Syndrome
PKU
XO = Turner’s Syndrome
XO = Down Syndrome,
XO = Turner’s Syndrome,
XO = DNA mutation
PKU= DNA mutation
PKU= DNA mutation
PKU= Down Syndrome
PKU= Down Syndrome