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1. Varieties of plants in which self-pollination produces
offspring that are identical to the parents are referred to as
a.
b.
c.
d.
Hybrids
The F2 generation
Monohybrid crosses
True-breeding
Correct answer: D
2. A monohybrid cross is
a. The second generation of a self-fertilized plant
b. A breeding experiment in which the parental varieties
have only one trait in common
c. A breeding experiment in which the parental varieties
differ only in one character
d. A breeding experiment in which the parental varieties
have only one prominent trait.
Correct answer: C
3. Which of the following statements regarding genotypes
and phenotypes is FALSE?
a. The genetic make-up of an organism constitutes its
genotype
b. An organism with two different alleles for a single trait is
said to be homozygous for that trait
c. Alleles are alternate forms of a gene
d. The expressed physical traits of an organism are called its
phenotype
Correct answer: B
4. The alleles of a gene are found at _______ chromosomes
a.
b.
c.
d.
The same locus on non-homologous
Different loci on homologous
Different loci on non-homologous
The same locus on homologous
Correct answer: D
5. The phenotypic ratio resulting from a dihybrid cross of
two heterozygous individuals showing independent
assortment is expected to be
a.
b.
c.
d.
1:2:1
3:1
9:1:1:3
9:3:3:1
Correct answer: D
6. Mendel’s law of independent assortment states that
a. Chromosomes sort independently of each other during
mitosis and meiosis
b. Independent sorting of genes produces polyploid plants
under some circumstances
c. Each pair of alleles segregates independently of the other
pairs of alleles during gamete formation
d. Genes are sorted concurrently during gamete formation
Correct answer: C
7. A testcross is
a. A mating between an individual of unknown genotype
and an individual homozygous recessive for the trait of
interest
b. A mating between an individual of unknown genotype
and an individual heterozygous for the trait of interest
c. A mating between two individuals heterozygous for the
trait of interest
d. A mating between two individuals of unknown genotype
Correct answer: A
8. Most genetic disorders in humans are caused by
a.
b.
c.
d.
Multiple alleles
Recessive alleles
A mutation that occurs in the egg, sperm, or zygote
Dominant alleles
Correct answer: B
9.Amniocentesis and chorionic villus sampling allow for ___and ____ of the fetus.
a.
b.
c.
d.
Imaging; karyotyping
Sexing; imaging
Karyotyping; biochemical testing
Direct observation; biochemical testing
Correct answer: C
10. Which of the following statements regarding prenatal
testing is FALSE?
a. Results from chorionic villus sampling come faster than
those from amniocentesis
b. Chorionic villus sampling is typically performed later in
the pregnancy than amniocentesis
c. Ultrasound imaging has no known risk.
d. Chorionic villus sampling and amniocentesis are usually
reserved for pregnancies with higher than usual risks of
complications
Correct answer: B
11. The expression of both alleles for a trait in a
heterozygous individual illustrates
a.
b.
c.
d.
Incomplete dominance
Codominance
Pleiotropy
Polygenic inheritance
Correct answer: B
12. All of the offspring of a cross between a red-flowered
plant and a white-flowered plant have pink flowers. This
means that the allele for red flowers is _____ to the allele for
white flowers.
a. Dominant
b. Codominant
c. Incompletely dominant
d. Recessive
Correct answer: C
13. Which of the following is an example of incomplete
dominance in humans?
a.
b.
c.
d.
Albinism
Hypercholesterolemia
Skin color
ABO blood groups
Correct answer: B
14. Genes located close together on the same chromosomes
are referred to as ______ genes and generally _________
a.
b.
c.
d.
Linked; sort independently during meiosis
Homologous; are inherited together
Linked; do not sort independently during meiosis
Codependent; do not sort independently during meiosis
Correct answer: C
15. A color blind woman marries a man who is not
colorblind. All of their sons, but none of their daughters , are
colorblind. Which of the following statements correctly
explains these results?
a. The gene for color vision is incompletely dominant to the
gene for sex determination
b. The gene for color vision is codominant with the gene for
sex determination
c. The gene for color vision is found on the X chromosome
d. The gene for color vision is found on the Y chromosome
Correct answer: C
16. sex-linked conditions are more common in men than in
women because
a. Men acquire two copies of the defective gene during
fertilization
b. Men need to inherit only one copy of the recessive allele
for the condition to be fully expressed.
c. The sex chromosomes are more active in men than in
women
d. The genes associated with the sex-linked conditions are
linked to the Y-chromosome, which determines
maleness.
Correct answer: B
17. Blood samples are taken from the heel of newborn
babies to test for the a mutation in the PKU gene, which if
left untreated and in severe cases, can lead to mental
retardation., reduced skin pigmentation, and seizures. Which
concept is being illustrated by this example?
a.
b.
c.
d.
Incomplete dominance
Polygenic inheritance
Pleiotropy
Codominance
Correct answer: C
18. Below are two statements:
Which (if any) applies to the law of segregation? Which (if
any) applies to the law of independent assortment?
1. Phenotypes for long tails and big eyes are inherited
separately in lab mice
2. A baby mouse inherits a maternal red eye allele and a
paternal black eye allele
a. 1 is segregation and 2 is independent assortment
b. 1 is independent assortment and 2 is segregation
c. Both 1 and 2 are segregation
d. Both 1 and 2 are independent assortment
Correct answer: B
19. You prepare a karyotype from a cell from an unknown
organism. Upon analysis, you find 22 pairs of chromosomes
that are each of equal length, and also a single pair that has
one chromosome longer than the other. What can you
conclude from this information?
a. The organism that this cell came from is likely a female
b. The organism that this cell came from is likely a male
c. The organism that this cell came from has a genetic
disease.
d. This cell is likely haploid
Correct answer: B
20. Justin has type A blood ad his wife Brittany has type B
blood. Justin’s parents both have type AB blood, and
Brittany’s parents also both have type AB blood. What are
the chances that Justin and Brittany’s son Theodore has type
A blood?
a.
b.
c.
d.
100%
75%
25%
0%
Correct answer: D
After reading the paragraph below, answer questions 21 and
22 given below:
A man and his wife are having trouble having a baby. Using
modern technologies, the woman’s eggs are removed,
fertilized with her husband’s sperm, and implanted into her
uterus. The procedure is successful, and the woman gives
birth to a healthy baby boy. After a while, though, they
discover that their son is colorblind, and has blood type O.
The woman claims that the child can’t be theirs since she
has blood type A and her husband has type B. Also neither
parent is colorblind, although one grandparent (the woman’s
grandfather) is also colorblind.
21. As a genetic counselor, you could explain to the parents
that
a. The eggs must have been accidentally switched, since the
baby’s blood type has to match one of his parents.
b. Each parent could have contributed one recessive allele,
resulting in type O blood.
c. The eggs must have been accidentally switched, since a
type A parent and a type B parent can have any type
children except O.
d. It is possible for the baby to have type O blood, since
type O is inherited through a dominant allele.
Correct answer: B
22. In regard to the baby’s colorblindness, a sex-linked
recessive trait, you explain that
a. Color blindness often appears randomly, even if neither
parent is colorblind.
b. The baby’s father must have a recessive allele for color
blindness.
c. Since color blindness is sex-linked, a son inherit color
blindness if his mother has the recessive colorblindness
allele.
d. The eggs must have been accidentally switched, since
males inherit sex-linked traits only from their fathers.
Correct answer: C
23. In pea plants, round peas are dominant (R) and shriveled
peas are recessive(r). Yellow peas (Y) are dominant and
green peas (y) are recessive. Using a Punnett square, find the
phenotypes of the parental plants that were used in this
cross by Mendel?
a.
b.
c.
d.
Rryy and RrYy
Rryy and rrYy
RRyy and rryy
RrYy and RrYy
Correct answer: A
24. If A is dominant to a and B is dominant to b, what is the
expected phenotypic ratio of the cross AaBb x AaBb
a.
b.
c.
d.
16:0:0:0
8:4:2:2
1:1:1:1
9:3:3:1
Correct answer: D
25. Which of the following statements best explains why
dominant alleles that cause lethal disorders are less common
than recessive alleles that cause lethal disorders?
a.Lethal disorders caused by dominant alleles are usually
more severe than lethal disorders caused by recessive alleles
b. Unlike lethal disorders caused by recessive alleles, lethal
disorders caused by dominant alleles usually cause the death
of the embryos.
c. Most individuals carrying a lethal dominant allele have the
disorder and die before they reproduce, whereas individuals
carrying a lethal recessive allele are more likely to be healthy
and reproduce.
d. The presence of a lethal dominant allele causes sterility
Correct answer: CVarieties of plants in which self-pollination
produces offspring that are identical to the parents are
referred to as