LFS100 Quiz 3 Flashcards
1
Q
If the liver cells of an animal have 24 chromosomes, how many chromosomes do its sperm cells have?
A
12
2
Q
A 9:3:3:1 phenotypic ratio is characteristic of which of the following?
A
a dihybrid cross
3
Q
A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates
A
dominance.
4
Q
Cystic fibrosis (CF) is a Mendelian disorder in the human population that is inherited as a recessive trait. Two normal parents have two children with CF. The probability of their next child having CF is which of the following?
A
1/4
5
Q
A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of
A
incomplete dominance.
6
Q
Chromosomes and genes are both present in pairs in all diploid cells
A
True
7
Q
Hypophosphatemia (vitamin D-resistant rickets) is inherited as an X-linked dominant disorder. An unaffected woman mates with a male with hypophosphatemia. What is the expected phenotypic ratio of their offspring?
A
1 daughter with hypophosphatemia : 1 normal son
8
Q
If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?
A
One gamete will be n + 1, one will be n - 1, and two will be n.
9
Q
Which of the following statements does NOT apply to the Watson and Crick model of DNA?
A
The two strands of the helix are held together by covalent bonds.
10
Q
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
A
leading strands and Okazaki fragments.
11
Q
The Y-shaped structure where the DNA double helix is actively unwound during DNA replication is called the
A
replication fork.
12
Q
RNA polymerase moves along the TEMPLATE strand of DNA in the ________ direction, and adds nucleotides to the ________ end of the growing transcript.
A
3’ to 5’; 3’
13
Q
What are ribosomes composed of?
A
both rRNA and protein
14
Q
When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signaling is
A
paracrine signaling.
15
Q
The general name for an enzyme that transfers phosphate groups from ATP to a protein is
A
protein kinase.
16
Q
Which of the following most likely would be an immediate result of growth factor binding to its receptor?
A
protein kinase activity
17
Q
Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?
A
a female somatic cell
18
Q
Crossing over usually contributes to genetic variation by exchanging chromosomal segments between
A
nonsister chromatids of homologues.
19
Q
Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that
A
traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.
20
Q
A sexually reproducing animal has two genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
A
HT
21
Q
When a disease is said to have a multifactorial basis, it means that
A
many factors, both genetic and environmental, contribute to the disease.
22
Q
SRY is
A
a gene present on the Y chromosome that triggers male development.
23
Q
The strands that make up DNA are antiparallel. This means that
A
the 5’ to 3’ direction of one strand runs in the opposite direction to the 5’ to 3’ direction of the other strand.
24
Q
Suppose one were provided with an actively dividing culture of E. coli bacteria to which radioactive thymine had been added. What would happen if a cell replicated once in the presence of this radioactive base?
A
DNA in both daughter cells would be radioactive.
25
A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is
UCA.
26
During translation, chain elongation continues until what happens?
A stop codon is encountered.
27
Paracrine signaling
involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid.
28
The general name for an enzyme that transfers phosphate groups from ATP to a protein is
protein kinase.
29
A(n) ________ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.
steroid
30
Which of the following statements about genes is incorrect?
Under normal circumstances, each chromosome contains precisely one gene.
31
Sexual life cycles result in greater variation among the offspring than do asexual life cycles.
True
32
What are Punnett squares used for?
predicting the result of genetic crosses between organisms of known genotypes
33
P = purple, pp = white. The offspring of a cross between two heterozygous purple-flowering plants (Pp × Pp) results in
purple-flowered plants and white-flowered plants.
34
Chromosomes and genes have copy numbers in the cell that increase after meiosis, and decrease during fertilisation
False
35
A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is
UCA.
36
G proteins and G-protein-linked receptors
are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms whose common ancestors diverged billions of years ago.
37
Independent assortment of chromosomes is a result of
the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
38
A 9:3:3:1 phenotypic ratio is characteristic of which of the following?
a dihybrid cross
39
A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates
dominance.
40
In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
tortoiseshell female; black male
41
Hypophosphatemia (vitamin D-resistant rickets) is inherited as an X-linked dominant disorder. An unaffected woman mates with a male with hypophosphatemia. What is the expected phenotypic ratio of their offspring?
1 daughter with hypophosphatemia : 1 normal son
42
Which of the following covalently connects segments of DNA
ligase
43
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
leading strands and Okazaki fragments.
44
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
A gene from an organism can theoretically be expressed by any other organism.
45
The old saying "one rotten apple spoils the whole barrel" is due to chemical signaling in plants via
release of ethylene gas, a plant hormone for ripening.
46
G proteins and G-protein-linked receptors
are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms whose common ancestors diverged billions of years ago.
47
Which of the following is NOT part of the phosphorylation cascade model?
GTP donates a phosphate group to an inactive protein kinase.
48
Which of the following most likely would be an immediate result of growth factor binding to its receptor?
protein kinase activity
49
Consider this pathway: epinephrine → G-protein-linked receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.
cAMP
50
Which of the following statements about genes is incorrect?
Under normal circumstances, each chromosome contains precisely one gene.
51
How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)?
16
52
The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because
one allele was completely dominant over another.
53
P = purple, pp = white. The offspring of a cross between two heterozygous purple-flowering plants (Pp × Pp) results in
purple-flowered plants and white-flowered plants.
54
A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of
incomplete dominance.
55
What is the chromosomal system for determining sex in mammals?
X-Y
56
When Thomas Hunt Morgan crossed his red-eyed F1 generation flies with each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?
The involved gene was on the X chromosome.
57
If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?
One gamete will be n + 1, one will be n - 1, and two will be n.
58
Because of the role of the mitochondria in producing cellular energy, mitochondrial diseases often affect the muscles and nervous system.
True
59
The strands that make up DNA are antiparallel. This means that
the 5' to 3' direction of one strand runs in the opposite direction to the 5' to 3' direction of the other strand.
60
Which enzyme catalyzes the elongation of a DNA strand in the 5' to 3' direction?
DNA polymerase
61
A new DNA strand elongates only in the 5' to 3' direction because
DNA polymerase can only add nucleotides to the free 3' end.
62
A particular triplet of bases in the template strand of DNA is AGT. The corresponding codon for the mRNA transcribed is
UCA.
63
What could happen to the target cells in an animal that lack receptors for local regulators?
They would not be able to multiply in response to growth factors from nearby cells.
64
Chemical signal pathways
often involve the binding of signal molecules to a protein on the surface of a target cell.
65
Which of the following is not true of cell communication systems?
Most signal receptors are bound to the outer membrane of the nuclear envelope.
66
Binding of a signal molecule to which type of receptor leads directly to a change in the distribution of anions and/or cations on opposite sides of the membrane?
ligand-gated ion channel
67
Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes?
a female somatic cell
68
In humans, each of the 22 maternal autosomes has a homologous paternal chromosome.
True
69
Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that
traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.
70
P = purple, pp = white. The offspring of a cross between two heterozygous purple-flowering plants (Pp × Pp) results in
purple-flowered plants and white-flowered plants.
71
Huntington's disease is an autosomal dominant condition with late age of onset in humans. In Australia, it afflicts approximately one in 14,000 people. If one parent (heterozygous) has the disease, what is the probability that his or her child will have the disease?
1/2
72
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (RW) offspring of red (RR) and white (WW) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?
roan × roan
73
SRY is
a gene present on the Y chromosome that triggers male development.
74
A recessive allele on the X chromosome is responsible for red-green colour blindness in humans. A woman with normal vision whose father is colour-blind marries a colour-blind male. What is the probability that a son of this couple will be colour-blind?
1/2
75
If nondisjunction occurs in meiosis II during gametogenesis, what will be the result at the completion of meiosis?
One gamete will be n + 1, one will be n - 1, and two will be n.
76
Because of the role of the mitochondria in producing cellular energy, mitochondrial diseases often affect the muscles and nervous system.
True
77
The strands that make up DNA are antiparallel. This means that
the 5' to 3' direction of one strand runs in the opposite direction to the 5' to 3' direction of the other strand.
78
What kind of molecule or substance is the primer that is used to initiate the synthesis of a new DNA strand?
RNA
79
What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
the nucleotide sequence of the template strand
80
The following question refers to Figure 17.6 (p 343 of the text Campbell Biology or in Assessment Task 1B area on Blackboard), a table of codons. What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG 3'
met-ser-ser-leu-ser-leu
81
All of the following are directly involved in translation EXCEPT
DNA.
82
The process of signal transduction usually begins
when the signal molecule changes the receptor protein in some way.
83
Of the following, a receptor protein in a membrane that recognises a chemical signal is most similar to
the active site of an enzyme in the cytoplasm that binds to a specific substrate.
84
Which of the following is the best explanation for the inability of an animal cell to reduce the Ca2+ concentration in its cytosol compared with the extracellular fluid?
insufficient ATP levels in the cytoplasm
85
An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
phospholipase C
86
Pea plants were particularly well suited for use in Mendel's breeding experiments for all of the following reasons except that
peas have an unusually long generation time.
87
A sexually reproducing animal has two genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
HT
88
In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (RW) offspring of red (RR) and white (WW) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?
roan × roan
89
If a human interphase nucleus of a person contains three Barr bodies, it can be assumed that the person
has four X chromosomes.
90
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately, what percentage of the nucleotides in this sample will be thymine?
12
91
Which of the following covalently connects segments of DNA
ligase
92
The process of signal transduction usually begins
when the signal molecule changes the receptor protein in some way.
93
What would be true for the signaling system in an animal cell that lacks the ability to produce GTP?
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
94
An animal deficient in adenylyl cyclase
would not respond properly to epinephrine.
95
Binding of a signal molecule to which type of receptor leads directly to a change in the distribution of anions and/or cations on opposite sides of the membrane?
ligand-gated ion channel
96
Secondary messengers are associated with which of the following?
transduction
97
Which of the following statements about genes is incorrect?
Under normal circumstances, each chromosome contains precisely one gene.
98
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt × BBtt will have black fur and long tails?
1/2
99
A woman who has blood type A, has a daughter who is type O and a son who is type B. Which of the following is a possible genotype for the mother?
IAi
100
In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
tortoiseshell female; black male
101
Hypophosphatemia (vitamin D-resistant rickets) is inherited as an X-linked dominant disorder. An unaffected woman mates with a male with hypophosphatemia. What is the expected phenotypic ratio of their offspring?
1 daughter with hypophosphatemia : 1 normal son
102
If a chromosome lacks certain genes, what has most likely occurred?
a deletion
103
Many mitochondrial genes encode proteins that play roles in the electron transport chain and ATP synthesis.
True
104
What kind of chemical bond is found between paired bases of the DNA double helix?
hydrogen
105
Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments
DNA polymerase I
106
What is the function of DNA polymerase III?
to add nucleotides to the end of a growing DNA strand
107
Which of the following is TRUE for both prokaryotic and eukaryotic gene expression?
RNA polymerase binds to the promoter region to begin transcription.
108
What could happen to the target cells in an animal that lack receptors for local regulators?
They would not be able to multiply in response to growth factors from nearby cells.
109
Which of the following is the best explanation for the inability of an animal cell to reduce the Ca2+ concentration in its cytosol compared with the extracellular fluid?
insufficient ATP levels in the cytoplasm
110
A(n) ________ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off.
steroid
111
Plant hormones can be characterized by all of the following except that they
function independently of other hormones
112
Which of the following statements about genes is incorrect?
Under normal circumstances, each chromosome contains precisely one gene.
113
In humans, each of the 22 maternal autosomes has a homologous paternal chromosome.
True
114
A plant with purple flowers is allowed to self-pollinate. Generation after generation, it produces purple flowers. This is an example of
true-breeding.
115
In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?
0
116
Males are more often affected by sex-linked traits than females because
males are hemizygous for the X chromosome.
117
An achondroplastic male dwarf with normal vision marries a colour-blind woman of normal height. The man's father was six-feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green colour blindness is X-linked recessive. How many of their sons would be expected to be colour-blind and of normal height?
half
118
One possible result of chromosomal breakage can be that a fragment reattaches to the original chromosome in a reverse orientation. This is called
inversion.
119
The strands that make up DNA are antiparallel. This means that
the 5' to 3' direction of one strand runs in the opposite direction to the 5' to 3' direction of the other strand.
120
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
leading strands and Okazaki fragments.
121
What is the function of DNA polymerase III?
to add nucleotides to the end of a growing DNA strand
122
Which of the following is TRUE for both prokaryotic and eukaryotic gene expression?
RNA polymerase binds to the promoter region to begin transcription.
123
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?
A gene from an organism can theoretically be expressed by any other organism.
124
The process of signal transduction usually begins
when the signal molecule changes the receptor protein in some way.
125
Of the following, a receptor protein in a membrane that recognises a chemical signal is most similar to
the active site of an enzyme in the cytoplasm that binds to a specific substrate.
126
Which of the following is/are true regarding the activity of a protein regulated by phosphorylation?
It depends on the balance in the cell between active kinase and active phosphatase molecules.
127
An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
phospholipase C
128
Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because
intracellular receptors are present only in target cells.
