CHAPTER 12—MENDEL, GENES, AND INHERITANCE
MULTIPLE CHOICE
1. Why can sickle cell disease cause death?
a.
The malformed red blood cells cannot transport oxygen.
b.
The malformed red blood cells cannot enter capillaries and, in fact, block them.
c.
The malformed blood cells assume a sickle-shape.
d.
The patient has two copies of the mutant gene.
e.
More cells assume the sickle shape as oxygen concentration in the tissues falls.
2. What is the main premise of the blending theory of inheritance that predominated before 1900?
a.
We inherit traits from both of our parents.
b.
Traits are inherited via a mixing of parental blood.
c.
You’re a perfect blend of traits from both of your biological parents.
d.
It explains the inheritance patterns of traits that skip a generation.
e.
It explains why children of one tall parent and one short parent generally have an adult
height midway between their parents’ heights.
3. When did Gregor Mendel perform his experiments with garden peas?
a.
in the 1860s, the same decade as the United States’ Civil War
b.
in the 1760s, predating the formation of the United States of America
c.
in the 1620s, the decade in which William Shakespeare died
d.
in the 1720s, the decade in which Bach composed the Brandenburg Concertos
e.
in the 1820s, the decade in which Ecuador became independent from Spain
4. Mendel studied what he called characters and traits. What is the relationship between these terms?
a.
Characters were heritable characteristics; traits were variations of characters.
b.
Traits were heritable characteristics; characters were variations of traits.
c.
Characters were the unknown package of transfer to the next generation; traits resulted
from this transfer.
d.
Characters were passed to the next generation; traits were never passed to the next
generation.
e.
Characters and traits were synonymous in Mendel’s writings.
5. If purple flower color is dominant in pea plants, a cross between P generation purple and white plants
will result in
a.
all purple flowers in the F1 generation.
b.
all white flowers in the F1 generation.
c.
all purple flowers in the F1 generation but a lighter purple than in the parents.
d.
mostly purple flowers in the P1 generation, with an occasional white flower.
e.
half of the plants having purple flowers, the other half having white flowers.
6. Mendel crossed true-breeding plants having yellow peas with plants having green peas. The resulting
plants all had yellow peas. An F1 cross resulted in of the plants having yellow peas and of the
plants having green peas. What does this tell you about the alleles for color?
a.
yellow is usually the dominant color, but sometimes green can be dominant
b.
green is the dominant color
c.
yellow is the dominant color
d.
yellow is the recessive color
e.
the F1 plants must have had some green peas that went unnoticed.
7. Use the product rule to determine the probability (P) of events X and Y both occurring.
a.
P = X2 + Y2
b.
P = X2Y2
c.
P = XY
d.
P = X + Y
e.
P = (X + Y)2
8. If the probability of X occurring is 1 in 4, and the probability of Y occurring is 1 in 5, the probability
of both occurring is
a.
(1/4)2 + (1/5)2 = (1/16) + (1/25) = (25/400) + (16/400) = 41/400.
b.
(1/4) + (1/5) = (5/20) + (4/20) = 9/20.
c.
(1/4)2(1/5)2 = (1/16)(1/25) = 1/400.
d.
(1/4)(1/5) = 1/20.
e.
(1/4 + 1/5)2 = (5/20 + 4/20)2 = (9/20)2 = 81/400.
9. Use the sum rule to determine the probability of either event X or event Y occurring if they cannot
occur simultaneously. (In the equations below, Px means probability of event X; Py means probability
of event Y.)
a.
= Px + Py
b.
= PxPy
c.
= (Px)2 + (Py)2
d.
= (Px + Py)2
e.
= Px2Py2
10. A testcross is used to
a.
determine if a parent with a dominant trait is heterozygous or homozygous.
b.
determine which allele is dominant.
c.
determine if the progeny of an experimental cross will get a random assortment of alleles.
d.
prove that an organism is true-breeding.
e.
cross an individual with a dominant phenotype with a homozygous dominant individual to
prove the alleles are indeed dominant.
11. Which of the following is a dihybrid cross?
a.
RrMM Rrmm
b.
RRMM rrmm
c.
RrMm RrMm
d.
rrMM RRmm
e.
RrMm rrmm
12. Which of the following is a test cross? (a “dash” means the allele’s identity is unknown)
a.
R-MM R-mm
b.
RRMM rrmm
c.
R-M- R-M-
d.
rrMM RRmm
e.
R-M- rrmm
13. Which of the following shows an F1 monohybrid cross?
a.
RrMM Rrmm
b.
RRMM rrmm
c.
Rr Rr
d.
rr RR
e.
Rr rr
14. A parent has a genotype of RrYy. What is the probability of having a gamete with the RY genotype?
a.
1/2
b.
1/4
c.
3/4
d.
1/8
e.
0
15. Mendel selected 7 traits in pea plants to study. What was lucky about this choice?
a.
Peas are easy to raise and have short life cycles.
b.
All 7 traits were easy to characterize.
c.
The 7 alleles segregated independently from each other.
d.
He knew enough mathematics to apply rules of probability to his results.
e.
The 7 traits were all located on the same plant chromosome.
16. Which individual established the connection between genes, meiosis, and fertilization?
a.
Gregor Mendel
b.
Hugo de Vries
c.
Carl Correns
d.
Erich von Tschermak
e.
Walter Sutton
17. Identify the disorder caused by a dominant allele.
a.
achondroplasia
b.
cystic fibrosis
c.
albinism
d.
sickle cell disease
e.
PKU
18. Your father is heterozygous for a recessive disorder. You know your mom has two “good” alleles.
What is the probability that you will have the disorder?
a.
0%
b.
25%
c.
50%
d.
75%
e.
100%
19. Your father is heterozygous for the recessive disorder phenylketonuria (PKU). You know your mom
has two “good” alleles. What is the probability that you will have the disorder?
a.
0% but you will have a 50% chance of passing the “bad” allele on to your children
b.
0% and you don’t need to worry about passing the “bad” allele on to your children
c.
25% for you and 25% for your children
d.
50% for you and 50% for your children
e.
50% for you and 25% that you’ll pass the “bad” allele on to your children
20. Your parents are both heterozygous for the recessive disorder phenylketonuria (PKU). What is the
probability that you will have the disorder?
a.
25% regardless of the health of your 3 siblings
b.
50% no matter whether or not you have siblings
c.
75% no matter whether or not you have siblings
d.
100% even if you are an only child
e.
25% but only if your three siblings are healthy.
21. R is the dominant allele for a round pea, r is the recessive allele for a wrinkled pea. If you cross plants
having round peas with plants having wrinkled peas,
a.
both pea plants are homozygous.
b.
you are conducting a dihybrid cross.
c.
you are crossing two parental pea plants.
d.
the progeny plants will all have wrinkled peas.
e.
you will be able to determine if the round pea plant is homozygous or heterozygous.
22. If your mother is heterozygous for Huntington disease, which is caused by a dominant allele, the odds
of your inheriting the disorder from her are
a.
1/4.
b.
1/2.
c.
3/4.
d.
1.
e.
0.
23. If your mother and father are both heterozygous for Huntington disease, which is caused by a
dominant allele, the odds of your having the disorder are
a.
1/4.
b.
1/2.
c.
3/4.
d.
1.
e.
0.
24. If your mother has cystic fibrosis, which is caused by a recessive allele, the odds of your inheriting the
disease are
a.
1/4.
b.
1/2.
c.
3/4.
d.
1.
e.
More information is needed to determine the odds.
25. If your mother and father both have cystic fibrosis, which is caused by a recessive allele, the odds of
your having cystic fibrosis are
a.
1/4.
b.
1/2.
c.
3/4.
d.
1.
e.
0.
26. If your mother and father both are healthy but carry the allele for cystic fibrosis, which is caused by a
recessive allele, the odds of your having at least one allele for the disorder are
a.
1/4.
b.
1/2.
c.
3/4.
d.
1.
e.
0.
27. If your mother and father both have cystic fibrosis, which is caused by a recessive allele, the odds of
your having only one allele for the disorder are
a.
1/4.
b.
1/2.
c.
3/4.
d.
1.
e.
0.
28. Round is the dominant trait for a pea; the recessive allele produces a wrinkled pea. How can you
obtain true-breeding pea plants having round peas with the least amount of work?
a.
Cross plants having round peas with plants having wrinkled peas. Select round pea plants
from the progeny because they are now true-breeding.
b.
Cross plants having round peas with other plants having round peas. Do this for multiple
generations.
c.
Cross plants having round peas with plants having wrinkled peas. Select round pea plants
from the progeny and do a test cross to determine which parental plants were homozygous
dominant. Use these homozygous pea plants as your true-breeding plants.
d.
Cross plants having round peas with plants having wrinkled peas. This will tell you which
round pea plants are homozygous dominant and are thus true-breeding.
e.
It’s not possible. You can only get true-breeding plants that have wrinkled peas.
29. The ability of an individual heterozygous for two different genes to produce its four gamete types in
equal numbers reflects Mendel’s Law(s) of
a.
Segregation.
b.
Independent Assortment.
c.
Punnett Squares.
d.
Chromosome Theory.
e.
Segregation and Independent Assortment.
30. A man and woman are each heterozygous for the autosomal recessive disorder cystic fibrosis. If they
want to have three children, what is the probability that only one of the children will have cystic
fibrosis?
a.
1/4
b.
3/4
c.
9/16
d.
9/64
e.
27/64
31. A cross is done between parents with genotypes aaBbCc and aaBbcc. What is the probability that
offspring will have the same genotype as the first parent?
a.
1/8
b.
1/4
c.
3/8
d.
3/16
e.
9/16
32. A cross is done between parents with genotypes aaBbCc and aaBbcc. What is the probability that
offspring will have the same phenotype as the first parent? Assume that capital letters indicate
dominant alleles and lower case letters indicate recessive alleles.
a.
1/8
b.
1/4
c.
3/8
d.
3/16
e.
9/16
33. The probability of rolling a die twice and getting a 2 and a 6 in no particular order is
a.
1/3
b.
1/4
c.
1/8
d.
1/18
e.
1/36
34. A man and woman are each heterozygous for the autosomal recessive gene for albinism. They already
have two non-albino children and want to have two more. What is the probability that their next two
children will be phenotypically identical to each other with regard to skin color (i.e., either both albino
or neither albino)?
a.
1/16
b.
3/16
c.
4/16
d.
9/16
e.
10/16
35. A plant of genotype CCdd is crossed to ccDD and the F1 testcrossed to ccdd. If the genes are on
different chromosomes, the percentage of ccdd offspring will be
a.
10
b.
20
c.
25
d.
30
e.
50
36. A couple are both heterozygous for the dominant allele for polydactyly. They want to have three
children. What is the probability that all three children will have polydactyly?
a.
3/4
b.
9/64
c.
1/64
d.
27/64
e.
1/2
37. Your mother has albinism, which is a recessive trait. You learn that your spouse’s mother also has
albinism. Neither you nor your spouse have albinism. What are the odds that your first child will have
albinism?
a.
0
b.
1/4
c.
1/2
d.
3/4
e.
1
38. Your mother has albinism, which is a recessive trait. Your father has cystic fibrosis, which is also a
recessive trait. You just got married and discover that your new father-in-law has albinism and cystic
fibrosis. What are the odds that your first child will have both albinism and cystic fibrosis?
a.
1/16.
b.
1/8.
c.
1/4.
d.
1/2.
e.
0.
39. Your mother has albinism, which is a recessive trait. Your father has cystic fibrosis, which is also a
recessive trait. You just got married and discover that your new father-in-law has albinism and cystic
fibrosis. What are the odds that your first child will have either albinism or cystic fibrosis, but not
both?
a.
1/16
b.
3/8
c.
1/8
d.
1/4
e.
0
40. Your mother has albinism, which is a recessive trait. Your father has cystic fibrosis, which is also a
recessive trait. You just got married and discover that your new father-in-law has albinism and cystic
fibrosis. What are the odds that your first child will have neither albinism nor cystic fibrosis?
a.
1/16
b.
3/8
c.
1/8
d.
9/16
e.
0
41. The reason why dwarf pea plants are shorter is because
a.
an enzyme involved in gibberellin hormone synthesis is missing.
b.
the plants completely stop growing shortly after sprouting.
c.
they cannot make any gibberellin hormone.
d.
they produce very little gibberellin hormone.
e.
they produce an excess of gibberellin hormone.
42. The key difference between incomplete dominance and codominance is
a.
with incomplete dominance, the recessive allele cannot be detected; in codominance, the
expression of the recessive allele is apparent.
b.
with incomplete dominance it is possible to detect the expression of a recessive allele; in
codominance, both alleles contribute equally to the phenotype.
c.
with codominance it is possible to detect the expression of a recessive allele; in incomplete
dominance, both alleles contribute equally to the phenotype.
d.
with incomplete dominance, it is possible to detect the expression of the dominant allele;
in codominance, both alleles contribute equally to the phenotype.
e.
the two terms mean the same thing.
43. You cross a pink snapdragon (CRCW) with a white snapdragon (CWCW). What percentage of the
progeny will be red?
a.
0%
b.
25%
c.
50%
d.
75%
e.
100%
44. Two snapdragons heterozygous for alleles that encode red and white flower color are crossed. If the
red and white alleles show incomplete dominance, what will be the phenotypes and ratios of the F2
generation?
a.
100% pink
b.
100% red
c.
50% white, 50% red
d.
25% red, 50% pink, 25% white
e.
25% pink, 50% white, 25% red
45. Your father has type B blood. Your mother has type O blood. You get tested and learn that your blood
is also type O. What does this tell you?
a.
You were adopted and your parents didn’t tell you.
b.
Your mother had a secret affair.
c.
Your father’s genotype is IBi and your mother’s genotype is ii.
d.
Your father’s genotype is IBIB and your mother’s genotype is ii.
e.
Your father’s genotype is IAIB and your mother’s genotype is ii.
46. You have type O blood (genotype ii). Who can you donate blood to in an emergency?
a.
type O only
b.
type B only
c.
type A only
d.
type AB only
e.
types A, B, AB, and O
47. You have type A blood (genotype IAi). Who can you donate blood to in an emergency?
a.
type O only
b.
type AB only
c.
type A only
d.
types A and B, not O
e.
types A and AB
48. The different alleles in human blood type are a demonstration of
a.
incomplete dominance.
b.
codominance.
c.
dominance and codominance.
d.
dominance and incomplete dominance.
e.
dominance, codominance, and incomplete dominance.
49. In snapdragons the red allele CR is incompletely dominant over the white allele CW. Which two plants
would you cross to produce a true-breeding pink snapdragon?
a.
pink with pink
b.
pink with red
c.
red with white
d.
pink with white
e.
it’s impossible to accomplish
50. If a monohybrid cross results in a 1:2:1 ratio for both the genotype and the phenotype in the F2
generation, then which type of inheritance might be at work?
a.
dominance
b.
incomplete dominance
c.
epistasis
d.
pleiotropy
e.
polygenic inheritance
51. If a woman has blood type O and a man has blood type AB, what is the probability that they will have
a child with blood type O?
a.
0
b.
1/16
c.
1/4
d.
1/2
e.
3/4
52. Mouse pigmentation is subject to epistasis of the B alleles by the d alleles. B (black) is dominant over
b (brown). D is dominant over d. Homozygous d is epistatic to the black and brown genes. Given this
information, what genotypes give you a white mouse?
a.
BBdd
b.
Bbdd
c.
bbDD
d.
bbDd
e.
BBdd and Bbdd
53. Mouse pigmentation is subject to epistasis of the B alleles by the d alleles. B (black) is dominant over
b (brown). D is dominant over d. Homozygous d is epistatic to the black and brown genes. Given this
information, what will result from a F1 cross between two mice?
a.
9/16 black, 3/16 brown, 4/16 white
b.
9/16 white, 3/16 brown, 4/16 black
c.
9/16 black, 6/16 brown, 1/16 white
d.
9/16 white, 6/16 brown, 1/16 black
e.
All black mice
54. According to Nicholas Katsanis at Duke University, which of the following are likely to be complex
traits?
a.
schizophrenia
b.
diabetes
c.
hypertension
d.
obesity
e.
all of these
55. We now know that some of the 7 alleles Mendel studied are on the same chromosome in pea plants.
Despite this, the law of independent assortment still applies. How can you explain this?
a.
There is recombination via the synaptonemal complex during mitosis.
b.
There is recombination via the synaptonemal complex during meiosis.
c.
The law of independent assortment applies to all alleles regardless of their arrangement on
chromosomes.
d.
Mendel was a good enough mathematician to design experiments that would result in the
predicted ratios.
e.
Mendel was incredibly lucky.
56. A patient presents the following symptoms: anemia, dilation of heart, lung damage and pneumonia,
rheumatism, abdominal pain, and kidney failure. After learning about their family history, you run a
genetic test for which disorder?
a.
Cystic fibrosis
b.
Albinism
c.
Sickle cell disease
d.
Achondroplasia
e.
Pleiotropy
Select the Exception
57. Which of the following is NOT one of Mendel’s hypotheses to explain the results of his P, F1 and F2
crosses?
a.
Adult plants carry a pair of genes that will determine the inheritance of each allele.
b.
If an adult plant has two different alleles, one is dominant over the other.
c.
Adult plants always have traits that are governed by a single pair of alleles, but the number
of possible alleles varies with each trait.
d.
The pairs of alleles separate in the formation of gametes so that each gamete gets one
allele of the pair.
e.
If an adult plant has two different alleles, one is recessive to the other.
58. Which of the following is NOT subject to polygenic inheritance?
a.
human height
b.
human skin color
c.
flower color in snapdragons
d.
seed color in wheat
e.
ear length in corn
MATCHING
Match each of the following terms with its correct definition.
a.
When displayed traits are unchanged over multiple generations
b.
The first generation of offspring from a parental cross
c.
True-breeding plants used in an initial cross
d.
A result of a cross between two first generation organisms
e.
The allele that is expressed no matter what other allele is present
f.
The allele that is expressed only if two identical copies are present.
g.
Any organism with 2 identical alleles of a gene
h.
Any organism with 2 different alleles of a gene
i.
An F1 heterozygote (for a single trait)
j.
The genetic makeup of an organism
k.
The physical traits of an organism
l.
The likelihood of something occurring if the occurrence is a matter of chance
m.
An organism that is heterozygous for two different traits
n.
Where an allele is found on a chromosome
o.
When one allele cannot completely mask the effects of another allele
p.
When alleles at one locus mask the expression of alleles at a different locus
q.
When different genes contribute to a particular phenotype
r.
When a single allele has multiple phenotypic effects.
59. F2 generation
60. F1 generation
61. dominant
62. homozygous
63. recessive
64. phenotype
65. dihybrid
66. heterozygous
67. pleiotropy
68. P generation
69. probability
70. genotype
71. true breeding
72. locus
73. polygenic inheritance
74. epistasis
75. monohybrid
76. incomplete dominance
264
Classification
Use the five types of allele interactions listed below for the following question(s).
a.
Dominance
b.
Incomplete dominance
c.
Codominance
d.
Epistasis
e.
Polygenic inheritance
77. Snapdragons have two alleles and three colors due to this.
78. Human blood type AB is an example of this allele interaction.
79. Mice have three colors of fur due to this allele interaction.
80. Human height is an example of this.
81. Peas being wrinkled or round is an example of this.
MODIFIED TRUE/FALSE
If the statement is true, answer “T“. If the statement is false, answer “F” and make it correct by
changing the underlined word(s) and writing the correct word(s) in the answer blank(s).
82. Cross-pollination occurs within a single plant while self-pollination occurs between two plants.
83. An F1 organism is always homozygous.
84. A dihybrid test cross should always result in 50% of the progeny being recessive for both traits.
85. A test cross always uses a homozygous recessive organism as one parent.
86. Dwarf pea plants have deficient levels of the hormone gibberellin.
87. Mendel knew about and understood incomplete dominance.
88. There is no limit to the number of alleles that exist for a gene.
89. The environment can impact the phenotype controlled by polygenic inheritance.
90. Polygenic inheritance is proof of the blending theory of inheritance.
SHORT ANSWER
91. Define epistasis and give an example.
92. Explain why human height appears to be a mixture of parental phenotypes when in fact height is
genetically based.
93. How is Mendel’s Principle of Independent Assortment related to meiosis?
94. What is the difference between polygenic and pleiotropy?
95. A couple wants to have a child but they are concerned that that child might have cystic fibrosis. After
taking a family history, you determine that neither of the two people have the disease, but one of them
(the female) had a sister with cystic fibrosis and the other (the male) had a dad with it. What do you
tell them?
ESSAY
96. Explain why Mendel’s work was so groundbreaking.
97. Would meiosis, when it was discovered, have been understood without Mendel’s work? Explain why
or why not, using Mendel’s three key findings about inheritance.