Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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1.
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For a couple of decades, biologists knew the nucleus contained DNA and proteins.
The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this
belief was that proteins are more complex than DNA. This is because
a. | proteins have a greater variety of three-dimensional forms than does
DNA. | b. | proteins have two different levels of structural organization; DNA has
four. | c. | proteins are made of 20 amino acids and DNA is made of four
nucleotides. | d. | Only A and C are correct. | e. | A, B, and C are
correct. |
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2.
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In his transformation experiments, Griffith observed that
a. | mutant mice were resistant to bacterial infections. | b. | mixing a heat-killed
pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells
into the pathogenic form. | c. | mixing a heat-killed nonpathogenic strain of
bacteria with a living pathogenic strain makes the pathogenic strain
nonpathogenic. | d. | infecting mice with nonpathogenic strains of bacteria makes them resistant to
pathogenic strains. | e. | mice infected with a pathogenic strain of
bacteria can spread the infection to other mice. |
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3.
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What does transformation involve in bacteria?
a. | the creation of a strand of DNA from an RNA molecule | b. | the creation of a
strand of RNA from a DNA molecule | c. | the infection of cells by a phage DNA
molecule | d. | the type of semiconservative replication shown by DNA | e. | assimilation of
external DNA into a cell |
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4.
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Avery and his colleagues purified various chemicals from pathogenic bacteria and
showed that ____ was (were) the transforming agent.
a. | DNA | b. | protein | c. | lipids | d. | carbohydrates | e. | phage |
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5.
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The following scientists made significant contributions to our understanding of
the structure and function of DNA. Place the scientists' names in the correct chronological
order, starting with the first scientist(s) to make a contribution. | I. | Avery, McCarty, and
MacLeod | | II. | Griffith | | III. | Hershey and Chase | | IV. | Meselson and Stahl | | V. | Watson and Crick | | |
a. | V, IV, II, I, III | b. | II, I, III, V, IV | c. | I, II, III, V, IV
| d. | I, II, V, IV, III | e. | II, III, IV, V, I
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6.
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After mixing a heat-killed, phosphorescent strain of bacteria with a living
non-phosphorescent strain, you discover that some of the living cells are now phosphorescent. The
best evidence that the ability to fluoresce is a heritable trait would be an observation that
a. | DNA passed from the heat-killed strain to the living strain. | b. | protein passed from
the heat-killed strain to the living strain. | c. | the phosphorescence in the living strain is
especially bright. | d. | descendants of the living cells are also
phosphorescent. | e. | both DNA and protein passed from the heat-killed strain to the living
strain. |
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7.
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For a science fair project, two students decided to repeat the Hershey and Chase
experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the
phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus,
labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't
this experiment work?
a. | There is no radioactive isotope of nitrogen. | b. | Radioactive nitrogen
has a half-life of 100,000 years, and the material would be too dangerous for too
long. | c. | Meselson and Stahl already did this experiment. | d. | Although there are
more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they
are more radioactive. | e. | Amino acids (and thus proteins) also have
nitrogen atoms; thus, the radioactivity would not distinguish between DNA and
proteins. |
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Match the investigator(s) to the appropriate discovery of about the nature of
genes.
| A. Frederick Griffith | | B. Alfred Hershey and Martha Chase | | C. Oswald Avery, Maclyn McCarty, and Colin MacLeod | | D. Erwin Chargaff | | E. Matthew Meselson and Franklin Stahl | |
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8.
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Chemicals from heat-killed S cells were purified. The chemicals were tested for
the ability to transform live R cells. The transforming agent was found to be DNA.
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9.
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Phage with labeled proteins or DNA was allowed to infect bacteria. It was shown
that the DNA, but not the protein, entered the bacterial cells, and was therefore the genetic
material.
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10.
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When T2 phages infect bacteria and make more viruses in the presence of
radioactive sulfur, what is the result?
a. | The viral DNA will be radioactive. | b. | The viral proteins will be
radioactive. | c. | The bacterial DNA will be radioactive. | d. | both A and B | e. | both A and
C |
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11.
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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?
a. | 12 | b. | 24 | c. | 31 | d. | 38 | e. | It cannot be
determined from the information provided. |
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12.
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Chargaff's analysis of the relative base composition of DNA was significant
because he was able to show that
a. | the relative proportion of each of the four bases differs from species to
species. | b. | the human genome is more complex than that of other species. | c. | the amount of A is
always equivalent to T, and C to G. | d. | both A and C | e. | both B and
C |
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13.
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All of the following can be determined directly from X-ray diffraction
photographs of crystallized DNA except the
a. | diameter of the helix. | b. | helical shape of DNA. | c. | sequence of
nucleotides. | d. | spacing of the nitrogenous bases along the helix. | e. | number of strands in
a helix. |
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14.
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The DNA double helix has a uniform diameter because ____, which have two rings,
always pair with ____, which have one ring.
a. | purines; pyrimidines | b. | pyrimidines; purines | c. | deoxyribose sugars;
ribose sugars | d. | ribose sugars; deoxyribose sugars | e. | nucleotides; nucleoside
triphosphates |
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15.
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What kind of chemical bond is found between paired bases of the DNA double
helix?
a. | hydrogen | b. | ionic | c. | covalent | d. | sulfhydryl | e. | phosphate |
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16.
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It became apparent to Watson and Crick after completion of their model that the
DNA molecule could carry a vast amount of hereditary information in its
a. | sequence of bases. | b. | phosphate-sugar backbones. | c. | complementary
pairing of bases. | d. | side groups of nitrogenous
bases. | e. | different five-carbon sugars. |
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17.
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In an analysis of the nucleotide composition of DNA, which of the following is
true?
a. | A = C | b. | A = G and C = T | c. | A + C = G +
T | d. | G + A = T + C | e. | both C and D |
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18.
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Which of the following statements is false when comparing prokaryotes
with eukaryotes?
a. | The prokaryotic chromosome is circular, whereas eukaryotic chromosomes are
linear. | b. | Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic
chromosomes have many. | c. | The rate of elongation during DNA replication
is higher in prokaryotes than in eukaryotes. | d. | Prokaryotes produce Okazaki fragments during
DNA replication, but eukaryotes do not. | e. | Eukaryotes have telomeres, and prokaryotes do
not. |
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19.
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The strands that make up DNA are antiparallel. This means that
a. | the twisting nature of DNA creates nonparallel strands. | b. | the 5' to
3' direction of one strand runs counter to the 5' to 3' direction of the other
strand. | c. | base pairings create unequal spacing between the two DNA strands. | d. | one strand is
positively charged and the other is negatively charged. | e. | one strand contains
only purines and the other contains only pyrimidines. |
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Use the figure below to answer the following questions.
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20.
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In the late 1950s, Meselson and Stahl grew bacteria in a medium containing
"heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the
results in the figure above would be expected after one DNA replication in the presence of
14N?
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21.
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A space probe returns with a culture of a microorganism found on a distant
planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N
medium for several generations and then transfer them to 14N medium. Which pattern in the figure
above would you expect if the DNA was replicated in a conservative manner?
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22.
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Which of the following is least related to the others on the list?
a. | Okazaki fragments | b. | replication fork | c. | telomerase | d. | DNA polymerase | e. | semiconservative
model |
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23.
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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. | b. | lagging strands and Okazaki
fragments. | c. | Okazaki fragments and RNA primers. | d. | leading strands and RNA
primers. | e. | RNA primers and mitochondrial DNA. |
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Refer to the list of enzymes below to answer the following questions. The
answers may be used once, more than once, or not at all.
| A. helicase | | B. nuclease | | C. ligase | | D. DNA polymerase I | | E. primase | |
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24.
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removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides
to the 3' end of Okazaki fragments
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25.
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covalently connects segments of DNA
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26.
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synthesizes short segments of RNA
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27.
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DNA-cutting enzymes used in the repair of DNA damage
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28.
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The Y-shaped structure where the DNA double helix is actively unwound during DNA
replication is called the
a. | replication fork. | b. | replication Y. | c. | elongation
junction. | d. | unwinding point. | e. | Y junction. |
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29.
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The leading and the lagging strands differ in that
a. | the leading strand is synthesized in the same direction as the movement of the
replication fork, and the lagging strand is synthesized in the opposite
direction. | b. | the leading strand is synthesized by adding nucleotides to the 3' end of the
growing strand, and the lagging strand is synthesized by adding nucleotides to the 5'
end. | c. | the leading strand is synthesized continuously, whereas the lagging strand is
synthesized in short fragments that are ultimately stitched together. | d. | both A and
B | e. | both A and C |
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30.
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Which of the following best describes the addition of nucleotides to a growing
DNA chain?
a. | A nucleoside triphosphate is added to the 5' end of the DNA, releasing a
molecule of pyrophosphate. | b. | A nucleoside triphosphate is added to the
3' end of the DNA, releasing a molecule of pyrophosphate. | c. | A nucleoside
diphosphate is added to the 5' end of the DNA, releasing a molecule of
phosphate. | d. | A nucleoside diphosphate is added to the 3' end of the DNA, releasing a molecule
of phosphate. | e. | A nucleoside monophosphate is added to the 3' end of the
DNA. |
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31.
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A new DNA strand elongates only in the 5' to 3' direction
because
a. | DNA polymerase begins adding nucleotides at the 5' end of the
template. | b. | Okazaki fragments prevent elongation in the 3' to 5'
direction. | c. | the polarity of the DNA molecule prevents addition of nucleotides at the 3'
end. | d. | replication must progress toward the replication fork. | e. | DNA polymerase can
only add nucleotides to the free 3' end. |
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32.
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Replicating the lagging strand of DNA-that is, adding bases in the 3'  5' direction-utilizes which of the following? a. | DNA ligase | b. | RNA primers | c. | Okazaki
fragments | d. | A and B only | e. | A, B, and C |
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33.
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What kind of molecule or substance is the primer that is used to initiate the
synthesis of a new DNA strand?
a. | RNA | b. | DNA | c. | protein | d. | phosphate | e. | sulfur |
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34.
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What is the function of topoisomerase?
a. | relieving strain in the DNA ahead of the replication fork | b. | elongation of new
DNA at a replication fork by addition of nucleotides to the existing chain | c. | the addition of
methyl groups to bases of DNA | d. | unwinding of the double
helix | e. | stabilizing single-stranded DNA at the replication
fork |
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35.
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What is the role of DNA ligase in the elongation of the lagging strand during
DNA replication?
a. | synthesize RNA nucleotides to make a primer | b. | catalyze the
lengthening of telomeres | c. | join Okazaki fragments
together | d. | unwind the parental double helix | e. | stabilize the unwound parental
DNA |
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36.
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All of the following are functions of DNA polymerase in DNA replication
except
a. | covalently adding nucleotides to the new strands. | b. | proofreading each
added nucleotide for correct base pairing. | c. | replacing RNA primers with
DNA. | d. | initiating a polynucleotide strand. | e. | none of the
above |
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37.
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Which of the following help to hold the DNA strands apart while they are being
replicated?
a. | primase | b. | ligase | c. | DNA
polymerase | d. | single-strand binding proteins | e. | exonuclease |
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38.
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Which of these mechanisms ensures that the DNA sequence in the genome remains
accurate?
a. | proofreading during DNA replication | b. | mismatch repair | c. | excision
repair | d. | complementary base pairing during DNA replication | e. | all of the
above |
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39.
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Which of the following is analogous to telomeres?
a. | the pull tab on a soft drink can | b. | the two ends of a shoelace | c. | the central spindle
that a CD fits around while in the case | d. | the mechanism of a zipper that allows the
separated parts to be joined | e. | the correct letters used to replace errors in a
document after they have been deleted in a word processor |
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40.
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Which of the following statements about telomeres is correct?
a. | They contain multiple copies of a short RNA sequence. | b. | They are present at
the ends of eukaryotic chromosomes. | c. | They can be extended by an enzyme called
telomerase. | d. | both A and B | e. | both B and C |
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41.
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Garrod hypothesized that "inborn errors of metabolism" such as
alkaptonuria occur because
a. | genes dictate the production of specific enzymes, and affected individuals have
genetic defects that cause them to lack certain enzymes. | b. | enzymes are made of
DNA, and affected individuals lack DNA polymerase. | c. | many metabolic enzymes use DNA as a cofactor,
and affected individuals have mutations that prevent their enzymes from interacting efficiently with
DNA. | d. | certain metabolic reactions are carried out by ribozymes, and affected individuals
lack key splicing factors. | e. | metabolic enzymes require vitamin cofactors,
and affected individuals have significant nutritional deficiencies. |
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The following questions refer to the following simple metabolic
pathway:
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42.
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According to Beadle and Tatum's hypothesis, how many genes are necessary
for this pathway?
a. | 0 | b. | 1 | c. | 2 | d. | 3 | e. | It cannot be
determined from the pathway. |
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43.
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A mutation results in a defective enzyme A. Which of the following would
be a consequence of that mutation?
a. | an accumulation of A and no production of B and C | b. | an accumulation of A
and B and no production of C | c. | an accumulation of B and no production of A and
C | d. | an accumulation of B and C and no production of A | e. | an accumulation of C
and no production of A and B |
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44.
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If A, B, and C are all required for growth, a strain mutant for the gene
encoding enzyme B would be capable of growing on which of the following media?
a. | minimal medium | b. | minimal medium supplemented with
"A" | c. | minimal medium supplemented with "B" | d. | minimal medium
supplemented with "C" | e. | answers B and C |
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45.
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Which of the following represents a similarity between RNA and DNA?
a. | Both are double-stranded. | b. | the presence of uracil | c. | the presence of an
OH group on the 2' carbon of the sugar | d. | nucleotides consisting of a phosphate, sugar,
and nitrogenous base | e. | Both are found exclusively in the
nucleus. |
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46.
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The nitrogenous base adenine is found in all members of which group?
a. | proteins, triglycerides, and testosterone | b. | proteins, ATP, and
DNA | c. | ATP, RNA, and DNA | d. | alpha glucose, ATP, and DNA | e. | proteins,
carbohydrates, and ATP |
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47.
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A particular triplet of bases in the template strand of DNA is AGT. The
corresponding codon for the mRNA transcribed is
a. | AGT. | b. | UGA. | c. | TCA. | d. | ACU. | e. | either UCA or TCA,
depending on wobble in the first base |
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Use the table of condons below to answer the following
questions.
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48.
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What amino acid sequence will be generated, based on the following mRNA codon
sequence?
5'AUG-UCU-UCG-UUA-UCC-UUG
a. | met-arg-glu-arg-glu-arg | b. | met-glu-arg-arg-gln-leu | c. | met-ser-leu-ser-leu-ser | d. | met-ser-ser-leu-ser-leu | e. | met-leu-phe-arg-glu-glu |
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49.
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A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the
following sequences in the coding strand of the DNA codes for this peptide?
a. | 3' UUU-CCC-AAA-GGG-UUU-CCC | b. | 3'
AUG-AAA-GGG-TTT-CCC-AAA-GGG | c. | 5'
TTT-CCC-AAA-GGG-TTT-CCC | d. | 5'
GGG-AAA-TTT-AAA-CCC-ACT-GGG | e. | 5'
ACT-TAC-CAT-AAA-CAT-TAC-UGA |
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50.
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A codon
a. | consists of two nucleotides. | b. | may code for the same amino acid as another
codon. | c. | consists of discrete amino acid regions. | d. | catalyzes RNA
synthesis. | e. | is found in all eukaryotes, but not in prokaryotes. |
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51.
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If the triplet CCC codes for the amino acid proline in bacteria, then in plants
CCC should code for
a. | leucine. | b. | valine. | c. | cystine. | d. | phenylalanine. | e. | proline. |
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52.
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Which of the following are transcribed from DNA?
a. | protein | b. | exons | c. | rRNA | d. | B and C only | e. | A, B, and
C |
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53.
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RNA polymerase and DNA polymerase differ in that
a. | RNA polymerase uses RNA as a template, and DNA polymerase uses a DNA
template. | b. | RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to
double-stranded DNA. | c. | RNA polymerase is much more accurate than DNA
polymerase. | d. | RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to
initiate DNA synthesis. | e. | RNA polymerase does not need to separate the
two strands of DNA in order to synthesize an RNA copy, whereas DNA polymerase must unwind the double
helix before it can replicate the DNA. |
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54.
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Which of the following is not a part of the eukaryotic transcription
initiation complex?
a. | promoter | b. | RNA polymerase | c. | transcription
factors | d. | snRNP | e. | TATA box |
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55.
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Which of the following is least related to the other items?
a. | translation | b. | TATA box | c. | transcription | d. | template strand | e. | RNA polymerase
II |
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56.
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Which of the following statements best describes the termination of
transcription in prokaryotes?
a. | RNA polymerase transcribes through the polyadenylation signal, causing proteins to
associate with the transcript and cut it free from the polymerase. | b. | RNA polymerase
transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release
the transcript. | c. | RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to
let go of the transcript. | d. | Once transcription has initiated, RNA
polymerase transcribes until it reaches the end of the chromosome. | e. | RNA polymerase
transcribes through a stop codon, causing the polymerase to stop advancing through the gene and
release the mRNA. |
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57.
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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'; 5' | b. | 3' to 5'; 3' | c. | 5' to 3';
5' | d. | 5' to 3'; 3' |
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58.
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All of the following are found in prokaryotic mRNA except
a. | the AUG codon. | b. | the UGA codon. | c. | introns. | d. | uracil. | e. | cytosine. |
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59.
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Which of the following helps to stabilize mRNA by inhibiting its
degradation?
a. | TATA box | b. | spliceosomes | c. | 5'
cap | d. | poly-A tail | e. | both C and D |
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60.
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Introns are significant to biological evolution because
a. | their presence allows exons to be moved around more easily, creating proteins with
new combinations of functional domains. | b. | they protect the mRNA from
degeneration. | c. | they are translated into essential amino acids. | d. | they maintain the
genetic code by preventing incorrect DNA base pairings. | e. | they correct
enzymatic alterations of DNA bases. |
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61.
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A mutation in which of the following parts of a gene is likely to be most
damaging to a cell?
a. | intron | b. | exon | c. | 5'
UTR | d. | 3' UTR | e. | All would be equally
damaging. |
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62.
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Which of the following is (are) true of snRNPs?
a. | They are made up of both protein and RNA. | b. | They bind to splice
sites at each end of the intron. | c. | They join together to form a large structure
called the spliceosome. | d. | Only A and C are true. | e. | A, B, and C are
true |
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63.
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All of the following are directly involved in translation except
a. | mRNA. | b. | tRNA. | c. | ribosomes. | d. | DNA. | e. | aminoacyl-tRNA
synthetase enzymes. |
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64.
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A particular triplet of bases in the coding sequence of DNA is AAA. The
anticodon on the tRNA that binds the mRNA codon is
a. | TTT. | b. | UUA. | c. | UUU. | d. | AAA. | e. | either UAA or TAA,
depending on first base wobble. |
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65.
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What is an anticodon part of?
a. | DNA | b. | tRNA | c. | mRNA | d. | a ribosome | e. | an activating
enzyme |
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66.
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A part of an mRNA molecule with the following sequence is being read by a
ribosome: 5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules (with their
anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match
the mRNA so that a dipeptide can form. tRNA
Anticodon | Amino Acid | GGC | Proline | CGU | Alanine | UGC | Threonine | CCG | Glycine | ACG | Cysteine | CGG | Alanine | | |
The
dipeptide that will form will be a. | cysteine-alanine. | b. | proline-threonine. | c. | glycine-cysteine. | d. | alanine-alanine. | e. | threonine-glycine. |
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67.
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The figure below represents tRNA that recognizes and binds a particular amino
acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino
acid?  a. | UGG | b. | GUG | c. | GUA | d. | UUC | e. | CAU |
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68.
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There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is
best explained by the fact that
a. | some tRNAs have anticodons that recognize two or more different
codons. | b. | the rules for base pairing between the third base of a codon and tRNA are
flexible. | c. | many codons are never used, so the tRNAs that recognize them are
dispensable. | d. | A and B only | e. | A, B, and C |
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69.
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What are ribosomes composed of?
a. | rRNA only | b. | proteins only | c. | both rRNA and
protein | d. | mRNA, rRNA, and protein | e. | mRNA, tRNA, rRNA, and
protein |
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70.
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Where is eukaryotic ribosomal RNA transcribed?
a. | the Golgi apparatus | b. | ribosomes | c. | the
nucleolus | d. | X chromosomes | e. | prokaryotic cells
only |
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71.
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What is the most abundant type of RNA?
a. | mRNA | b. | tRNA | c. | rRNA | d. | pre-mRNA | e. | hnRNA |
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72.
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From the following list, which is the first event in translation in
eukaryotes?
a. | elongation of the polypeptide | b. | base pairing of activated methionine-tRNA to
AUG of the messenger RNA | c. | binding of the larger ribosomal subunit to
smaller ribosomal subunits | d. | covalent bonding between the first two amino
acids | e. | Both B and D occur simultaneously. |
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73.
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Choose the answer that has these events of protein synthesis in the proper
sequence.
1. An aminoacyl-tRNA binds to the A site.
2. A peptide bond forms between the new
amino acid and a polypeptide chain.
3. tRNA leaves the P site, and the P site remains
vacant.
4. A small ribosomal subunit binds with mRNA.
5. tRNA translocates to the P
site.
a. | 1, 3, 2, 4, 5 | b. | 4, 1, 2, 5, 3 | c. | 5, 4, 3, 2,
1 | d. | 4, 1, 3, 2, 5 | e. | 2, 4, 5, 1, 3 |
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74.
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Which of the following is not directly involved in the process of
translation?
a. | ligase | b. | tRNA | c. | rRNA | d. | mRNA | e. | aminoacyl-tRNA
synthetase |
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75.
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Which of the following components are present upon the completion of translation
initiation?
a. | small ribosomal subunit | b. | large ribosomal subunit | c. | initiator
tRNA | d. | A and C only | e. | A, B, and C |
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76.
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During translation, chain elongation continues until what happens?
a. | No further amino acids are needed by the cell. | b. | All tRNAs are
empty. | c. | The polypeptide is long enough. | d. | A stop codon is
encountered. | e. | The ribosomes run off the end of mRNA. |
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77.
|
As a ribosome translocates along an mRNA molecule by one codon, which of the
following occurs?
a. | The tRNA that was in the A site moves into the P site. | b. | The tRNA that was in
the P site moves into the A site. | c. | The tRNA that was in the P site moves to the E
site and is released. | d. | The tRNA that was in the A site departs from
the ribosome. | e. | Both A and C are correct. |
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78.
|
What are polyribosomes?
a. | groups of ribosomes reading a single mRNA simultaneously | b. | ribosomes containing
more than two subunits | c. | multiple copies of ribosomes associated with
giant chromosomes | d. | aggregations of vesicles containing ribosomal
RNA | e. | ribosomes associated with more than one tRNA |
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79.
|
What is one function of a signal peptide?
a. | to direct an mRNA molecule into the cisternal space of the ER | b. | to bind RNA
polymerase to DNA and initiate transcription | c. | to terminate translation of the messenger
RNA | d. | to translocate polypeptides across the ER membrane | e. | to signal the
initiation of transcription |
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80.
|
Which of the following is least related to the other items?
a. | exons | b. | introns | c. | RNA
splicing | d. | signal-recognition particles (SRPs) | e. | mRNA |
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81.
|
Which of the following is not related to ribosomal activity?
a. | A site | b. | spliceosome | c. | codon
recognition | d. | peptide bond formation | e. | P site |
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82.
|
When does translation begin in prokaryotic cells?
a. | after a transcription initiation complex has been formed | b. | during
transcription | c. | after the 5' caps are converted to mRNA | d. | once the pre-mRNA
has been converted to mRNA | e. | as soon as the DNA introns are removed from the
template |
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83.
|
Which of the following statements are true about protein synthesis in
prokaryotes?
a. | Translation can begin while transcription is still in progress. | b. | Extensive RNA
processing is required before prokaryotic transcripts can be translated. | c. | Prokaryotic cells
have complicated mechanisms for targeting proteins to the appropriate cellular
organelles. | d. | Only A and B are true. | e. | A, B, and C are
true. |
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84.
|
Of the following types of mutations, which one is likely to be the most
common?
a. | point mutation | b. | missense mutation | c. | base-pair
substitution | d. | nonsense mutation | e. | frameshift
mutation |
|
|
|
Each of the following is a modification of the sentence
THECATATETHERAT. | A.THERATATETHECAT | | B. THETACATETHERAT | | C. THECATARETHERAT | | D.
THECATATTHERAT | | E. CATATETHERAT | |
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85.
|
Which of the above is analogous to a frameshift mutation?
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|
86.
|
Which of the above is analogous to a single substitution mutation?
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87.
|
Sickle-cell disease is probably the result of which kind of mutation?
a. | point | b. | frameshift | c. | nonsense | d. | nondisjunction | e. | both B and
D |
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88.
|
A frameshift mutation could result from
a. | a base insertion only. | b. | a base deletion only. | c. | a base substitution
only. | d. | deletion of three consecutive bases. | e. | either an insertion or a deletion of a
base. |
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89.
|
Which of the following DNA mutations is the most likely to be damaging to the
protein it specifies?
a. | a base-pair deletion | b. | a codon substitution | c. | a substitution in
the last base of a codon | d. | a codon deletion | e. | a point
mutation |
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90.
|
Which point mutation would be most likely to have a catastrophic effect on the
functioning of a protein?
a. | a base substitution | b. | a base deletion near the start of a
gene | c. | a base deletion near the end of the coding sequence, but not in the terminator
codon | d. | deletion of three bases near the start of the coding sequence, but not in the
initiator codon | e. | a base insertion near the end of the coding sequence, but not in the terminator
codon |
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|
91.
|
Which of the following is (are) true about viruses?
a. | Viruses are classified below the cellular level of biological
organization. | b. | A single virus particle contains both DNA and RNA. | c. | Even small virus
particles are visible with light microscopes. | d. | Only A and B are true. | e. | A, B, and C are
true. |
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92.
|
Which of the following is not a reason scientists suspected that
something other than bacteria was the cause of tobacco mosaic disease?
a. | Passing infectious sap through a fine filter failed to remove the infectious
agent. | b. | Treating infectious sap with alcohol failed to remove the infectious
agent. | c. | No cells could be seen in the infectious sap using a light
microscope. | d. | The infectious agent in the sap could reproduce, as its ability to cause disease was
undiluted even after many transfers from plant to plant. | e. | The infectious agent
could not be cultivated on nutrient media in petri dishes or in test
tubes. |
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93.
|
Which of the following is a characteristic of all viruses?
a. | a nucleic acid genome | b. | a protein capsid | c. | a viral
envelope | d. | A and B only | e. | A, B, and C |
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94.
|
Viral genomes can consist of any of the following except
a. | double-stranded DNA. | b. | double-stranded RNA. | c. | single-stranded
DNA. | d. | single-stranded RNA. | e. | helical
capsomeres. |
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95.
|
The host range of a virus is determined by
a. | the proteins on its surface. | b. | whether its nucleic acid is DNA or
RNA. | c. | the proteins on the surface of the host cell. | d. | the enzymes produced
by the virus before it infects the cell. | e. | both A and C |
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96.
|
Viruses are referred to as obligate parasites because
a. | they cannot reproduce outside of a host cell. | b. | viral DNA always
inserts itself into host DNA. | c. | they invariably kill any cell they
infect. | d. | they can incorporate nucleic acids from other viruses. | e. | they must use
enzymes encoded by the virus itself. |
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97.
|
Which of the following is characteristic of the lytic cycle?
a. | Many bacterial cells containing viral DNA are produced. | b. | Viral DNA is
incorporated into the host genome. | c. | The viral genome replicates without destroying
the host. | d. | A large number of phages are released at a time. | e. | The virus-host
relationship usually lasts for generations. |
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98.
|
Bacteriophage DNA that have become integrated into the host cell chromosome are
called
a. | intemperate bacteriophages. | b. | transposons. | c. | prophages. | d. | T-even phages. | e. | plasmids. |
|
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99.
|
Which of the following statements about the lysogenic cycle of lambda (  . phage is incorrect? a. | After infection the viral genes immediately turn the host cell into a
lambda-producing factory, and the host cell then lyses. | b. | Most of the prophage
genes are silenced by the product of a particular prophage gene. | c. | The phage genome
replicates along with the host genome. | d. | Certain environmental triggers can cause the
phage to exit the host genome, switching from the lysogenic to the lytic cycle. | e. | The phage DNA is
incorporated by genetic recombination (crossing over. into a specific site on the host cell's
DNA. |
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100.
|
What is the function of the single-stranded RNA in certain animal
viruses?
a. | It can serve directly as mRNA. | b. | It can serve as a template for mRNA
synthesis. | c. | It can serve as a template for DNA synthesis. | d. | Only A and C are
correct. | e. | A, B, and C are correct. |
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101.
|
Viruses with single-stranded RNA that acts as a template for DNA synthesis are
known as
a. | retroviruses. | b. | proviruses. | c. | viroids. | d. | bacteriophages. | e. | lytic
phages. |
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|
102.
|
What is the function of reverse transcriptase in retroviruses?
a. | It hydrolyzes the host cell's DNA. | b. | It uses viral RNA as
a template for DNA synthesis. | c. | It converts host cell RNA into viral
DNA. | d. | It translates viral RNA into proteins. | e. | It uses viral RNA as a template for making
complementary RNA strands. |
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|
103.
|
The membrane making up the viral envelope can come from
a. | the virus itself, using enzymes encoded by the virus. | b. | the nuclear membrane
of an infected cell. | c. | the plasma membrane of an infected
cell. | d. | both A and B | e. | both B and C |
|
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|
104.
|
Viral envelopes contain proteins with covalently attached carbohydrate groups
called
a. | glycoproteins. | b. | proteosugars. | c. | carbopeptides. | d. | peptidocarbs. | e. | carboproteins. |
|
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|
105.
|
The simplest infectious biological systems are
a. | bacteria. | b. | viruses. | c. | viroids. | d. | both A and B | e. | both B and
C |
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|
106.
|
Which of the following is a true statement?
a. | Viruses are uncommon. | b. | Viruses can cause diarrhea, colds, and
measles. | c. | All viruses have a similar capsid and membranous envelope. | d. | All viruses contain
the nucleic acid RNA. | e. | Viruses only invade animal
cells. |
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|
107.
|
Which of the following can be effective against viral diseases?
a. | vaccination | b. | nucleoside analogs that inhibit DNA
synthesis | c. | antibiotics | d. | A and B only | e. | A, B, and
C |
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|
108.
|
RNA viruses appear to have higher rates of mutation because
a. | RNA nucleotides are more unstable than DNA nucleotides. | b. | replication of their
genomes does not involve the proofreading steps of DNA replication. | c. | RNA viruses
replicate faster. | d. | RNA viruses can incorporate a variety of
nonstandard bases. | e. | RNA viruses are more sensitive to
mutagens. |
|
|
|
Refer to the treatments listed below to answer the following
questions.
You isolate an infectious substance that is capable of causing disease in
plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You
have four methods at your disposal that you can use to analyze the substance in order to determine
the nature of the infectious agent. | I. | treating the substance with nucleases that destroy all nucleic acids and then
determining whether it is still infectious | | II. | filtering the substance to remove all elements smaller than
what can be easily seen under a light microscope | | III. | culturing the substance by itself on nutritive medium,
away from any plant cells | | IV. | treating the sample with proteases that digest all proteins and then determining whether it
is still infectious | | |
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|
109.
|
If you already knew that the infectious agent was either bacterial or viral,
which treatment would allow you to distinguish between these two possibilities?
a. | I | b. | II | c. | III | d. | IV | e. | either II or
IV |
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|
|
110.
|
Which treatment would you use to determine if the agent is a prion?
a. | I only | b. | II only | c. | III
only | d. | IV only | e. | either I or IV |
|
|
|
111.
|
Which of the following contributes to the emergence of viral disease?
a. | production of new virus strains through mutation | b. | spread of existing
virus from one host species to another | c. | transformation from lytic to lysogenic
activity | d. | A and B only | e. | A, B, and C |
|
|
|
112.
|
Which of the following is true of plant virus infections?
a. | They can be controlled by the use of antibiotics. | b. | They are spread
throughout a plant by passing through the plasmodesmata. | c. | They have little
effect on plant growth. | d. | Only A and B are correct. | e. | A, B, and C are
correct. |
|
|
|
113.
|
Which of the following represents a difference between viruses and
viroids?
a. | Viruses infect many types of cells, whereas viroids infect only prokaryotic
cells. | b. | Viruses have capsids composed of protein, whereas viroids have no
capsids. | c. | Viruses contain introns; viroids have only exons. | d. | Viruses always have
genomes composed of DNA, whereas viroids always have genomes composed of RNA. | e. | Viruses cannot pass
through plasmodesmata; viroids can. |
|
|
|
114.
|
The difference between vertical and horizontal transmission of
plant viruses is that
a. | vertical transmission refers to the transmission of a virus from a parent plant to
its progeny, and horizontal transmission refers to one plant spreading the virus to another
plant. | b. | vertical transmission refers to the spread of viruses from upper leaves to lower
leaves of the plant, and horizontal transmission refers to the spread of a virus among leaves at the
same general level. | c. | vertical transmission refers to the spread of
viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission
refers to the spread of viruses among plants of similar size. | d. | vertical
transmission refers to the transfer of DNA from one type of plant virus to another, and horizontal
transmission refers to the exchange of DNA between two plant viruses of the same
type. | e. | vertical transmission refers to the transfer of DNA from a plant of one species to a
plant of a different species, and horizontal transmission refers to the spread of viruses among
plants of the same species. |
|
|
|
115.
|
What are prions?
a. | misfolded versions of normal brain protein | b. | tiny molecules of
RNA that infect plants | c. | viral DNA that has had to attach itself to the
host genome | d. | viruses that invade bacteria | e. | a mobile segment of
DNA |
|
|
|
116.
|
Reproduction in bacteria requires
a. | the production of a mitotic spindle. | b. | a plasmid. | c. | cyclic
AMP. | d. | replication of DNA. | e. | both B and D |
|
|
|
117.
|
What is the most common source of genetic diversity in a bacterial
colony?
a. | transposons | b. | plasmids | c. | meiotic
recombination | d. | crossing over | e. | mutation |
|
|
|
Use the following answers for the following questions. The answers may be
used once, more than once, or not at all.| A.
transduction | | B. transposition | | C. translation | | D. transformation | | E.
conjugation | |
|
|
|
118.
|
External DNA is assimilated by a cell.
|
|
|
119.
|
DNA is transferred from one bacterium to another by a virus.
|
|
|
120.
|
In biotechnology, genes are commonly introduced into bacterial cells by
incubating the cells together with DNA and high concentrations of calcium ions. This is an example
of
a. | transformation. | b. | translocation. | c. | transduction. | d. | conjugation. | e. | transposition. |
|
|
|
121.
|
An Hfr bacterium is one that has
a. | at least one plasmid present in the cytosol. | b. | a special
recognition site that will take up closely related DNA from its environment. | c. | several insertion
sequences scattered throughout its chromosome. | d. | several copies of a single transposon repeated
randomly throughout its chromosome. | e. | a plasmid that has become integrated into its
chromosome. |
|
|
|
122.
|
Which of the following statements regarding transposons is not
true?
a. | Transposons are genes that encode sex pili and enable plasmid transfers between
bacteria. | b. | Transposons are found in both prokaryotes and eukaryotes. | c. | Transposons can move
from a plasmid to the bacterial circular chromosome. | d. | Transposons may replicate at an original site
and insert a copy at another site. | e. | Transposons may carry only the genes necessary
for insertion. |
|
|
|
123.
|
An R plasmid can
a. | facilitate bacterial resistance to antibiotics. | b. | adjust the rates of
metabolic pathways. | c. | repress gene expression. | d. | convert an
F+ to an F– bacterium. | e. | reverse the direction of
transcription. |
|
|
|
124.
|
What does the operon model attempt to explain?
a. | the coordinated control of gene expression in bacteria | b. | bacterial resistance
to antibiotics | c. | how genes move between homologous regions of DNA | d. | the mechanism of
viral attachment to a host cell | e. | horizontal transmission of plant
viruses |
|
|
|
125.
|
All of the following are made up of nucleic acid except a
a. | repressor. | b. | structural gene. | c. | promoter. | d. | regulatory gene. | e. | operator. |
|
|
|
126.
|
The role of a metabolite that controls a repressible operon is to
a. | bind to the promoter region and decrease the affinity of RNA polymerase for the
promoter. | b. | bind to the operator region and block the attachment of RNA polymerase to the
promoter. | c. | increase the production of inactive repressor proteins. | d. | bind to the
repressor protein and inactivate it. | e. | bind to the repressor protein and activate
it. |
|
|
|
127.
|
The tryptophan operon is a repressible operon that is
a. | permanently turned on. | b. | turned on only when tryptophan is present in
the growth medium. | c. | turned off only when glucose is present in the
growth medium. | d. | turned on only when glucose is present in the growth medium. | e. | turned off whenever
tryptophan is added to the growth medium. |
|
|
|
For the following questions, match the terms below with the appropriate
phrase or description below. Each term can be used once, more than once, or not at
all.| A. operon | | B. inducer | | C.
promoter | | D. repressor | | E. corepressor | |
|
|
|
128.
|
A lack of this nonprotein molecule would result in the inability of the cell to
"turn off" genes.
|
|
|
129.
|
A mutation that inactivates the regulatory gene of a repressible operon in an
E. coli cell would result in
a. | continuous transcription of the structural gene controlled by that
regulator. | b. | complete inhibition of transcription of the structural gene controlled by that
regulator. | c. | irreversible binding of the repressor to the operator. | d. | inactivation of RNA
polymerase. | e. | both B and C |
|
|
|
130.
|
Transcription of the structural genes in an inducible operon
a. | occurs all the time. | b. | starts when the pathway's substrate is
present. | c. | starts when the pathway's product is present. | d. | stops when the
pathway's product is present. | e. | does not produce
enzymes. |
|
|
|
131.
|
How does active CAP induce expression of the genes of the lactose operon?
a. | It terminates production of repressor molecules. | b. | It degrades the
substrate allolactose. | c. | It stimulates splicing of the encoded
genes. | d. | It stimulates the binding of RNA polymerase to the promoter. | e. | It binds steroid
hormones and controls translation. |
|
|
|
132.
|
For a repressible operon to be transcribed, which of the following must be
true?
a. | A corepressor must be present. | b. | RNA polymerase and the active repressor must be
present. | c. | RNA polymerase must bind to the promoter, and the repressor must be
inactive. | d. | RNA polymerase cannot be present, and the repressor must be
inactive. | e. | RNA polymerase must not occupy the promoter, and the repressor must be
inactive. |
|
|
|
133.
|
Of the following, which is least related to the others?
a. | corepressor | b. | repressor | c. | inducer | d. | transposon | e. | cAMP receptor
protein |
|
|
|
134.
|
The condensed chromosomes observed in mitosis include all of the following
structures except
a. | nucleosomes. | b. | 30-nm fibers. | c. | 300-nm
fibers. | d. | looped domain. | e. | ribosomes. |
|
|
|
135.
|
Under the electron microscope, unfolded chromatin resembles "beads on a
string." What do the "beads" represent?
a. | nucleosomes | b. | ribosomes | c. | beadosomes | d. | molecules of DNA polymerase | e. | molecules of RNA
polymerase |
|
|
|
136.
|
If a cell were unable to produce histone proteins, which of the following would
be expected to occur?
a. | There would be an increase in the amount of "satellite" DNA produced during
centrifugation. | b. | The cell's DNA couldn't be packed into its nucleus. | c. | Spindle fibers would
not form during prophase. | d. | Amplification of other genes would compensate
for the lack of histones. | e. | Pseudogenes would be transcribed to compensate
for the decreased protein in the cell. |
|
|
|
137.
|
Which of the following statements about histones is incorrect?
|