Exam 2 (Lect. Qs 16-21)

Question 1

A gene whose product catabolizes DDT as a carbon source is “induced” by DDT. What does this mean?
A. The gene is only transcribed in the presence of DDT.
B. The gene is only transcribed in the absence of DDT.
C. DDT is a protein that binds to turn the gene “ON.”
D. DDT is a protein that binds to turn the gene “OFF.”
E. The cell is killed by DDT

Answer 1

The gene is only transcribed in the presence of DDT.

Question 2

An inducer used with a positive regulatory system . . .
A. is called a “co-repressor”
B. prevents the repressor protein from binding to the DNA
C. helps the activator protein bind to the DNA
D. binds directly to the DNA instead of to a protein
E. is impossible - inducers are used only with negative regulatory systems.

Answer 2

helps the activator protein bind to the DNA

Question 3

Cells in a biofilm grow at a much higher cell density than planktonic cells. What is a result of such dense growth?
A. All the genes in the cell will be turned on.
B. More genes will be turned on than in planktonic growth.
C. Cells will be more motile than planktonic cells.
D. Genes that are induced by homoserine lactones (HSL) will be turned on.
E. Nothing - bacteria have no way of knowing how many other cells are present.

Answer 3

Genes that are induced by homoserine lactones (HSL) will be turned on.

Question 4

What is a “response regulator” in a two component regulatory system?
A. The environmental signal
B. The inducer of the environmental signal
C. The co-repressor for genes that respond to the environmental signal
D. A protein that turns genes on or off in response to the environmental signal
E. A gene that is turned on or off in response to the environmental signal

Answer 4

A protein that turns genes on or off in response to the environmental signal

Question 5

The protein TrmB binds to the promoter region of the malE gene. The sugar trehalose binds to TrmB. In the presence of trehalose, the binding of TrmB to the malE gene is inhibited, and the malE gene is transcribed. TrmB is an example of . . .
A. an inducer
B. a positive control protein
C. an operator
D. a repressor
E. a repressible gene

Answer 5

a repressor

Question 6

The protein TyrR can activate some genes and simultaneously repress others. This depends on . . .
A. whether TyrR binds upstream or downstream of the promoter
B. whether an environmental inducer or a co-repressor is present
C. whether TyrR has a negative or a positive charge
D. whether TyrR is bound to an inducer gene or to a repressor gene
E. whether or not a sigma factor recognizes the promoter for TyrR

Answer 6

whether TyrR binds upstream or downstream of the promoter

Question 7

How does an inducer induce a gene without being present inside the cell?
A. By altering the lipid bilayer, which then alters the DNA around a gene
B. By phosphate transfer between a membrane sensor kinase and a cytoplasmic regulatory protein
C. By binding a repressor and preventing the repressor from entering the cell
D. The inducer must be phosphorylated so it can phosphorylate the DNA
E. It can’t. The inducer must at least be able to enter the cell to induce a gene

Answer 7

By phosphate transfer between a membrane sensor kinase and a cytoplasmic regulatory protein

Question 8

The mechanism whereby a cryptic gene is inserted downstream of an active promoter, as occurs in
Neisseria gonorrhoeae, is called . . .
A. Promoter induction
B. Two-component regulation
C. Cassette switching
D. Quorum sensing
E. Exon shuffling

Answer 8

Cassette switching

Question 9

What is an “operon”?
A. A region of DNA in which multiple genes are regulated by one promoter
B. The sequence of RNA to which repressor proteins bind
C. The sequence of DNA to which activator proteins bind
D. The induction of a whole set of genes that all recognize the same sigma factor
E. An environmental signal that binds to a repressor protein to turn OFF a gene

Answer 9

A region of DNA in which multiple genes are regulated by one promoter

Question 10

Raffinose is the inducer of the rafB gene. Which of the following MUST be true about raffinose?
A. it binds upstream of the rafB promoter
B. it binds to an activator protein
C. it is a protein
D. rafB mRNA is synthesized in its presence
E. it functions in a positive control system

Answer 10

rafB mRNA is synthesized in its presence

Question 11

Which picture represents the lac regulatory region in the absence of both glucose and lactose?

Answer 11

A and O sitting on line, promoter pointed to O

Question 12

Why is it an advantage for Neisseria gonorrhoeae to undergo cassette switching of its pilin genes?
A. This allows inducers to regulate genes without entering the cell.
B. It allows several pilin genes to be transcribed simultaneously.
C. Neisseria can attach to surfaces better with different pilus cassettes.
D. It enhances horizontal gene transfer of pilin genes between cells.
E. New pilin proteins can be made without involving another regulatory event.

Answer 12

New pilin proteins can be made without involving another regulatory event

Question 13

What advantage does it give prokaryotes to have genes organized in operons?
A. The genes can all be replicated on one piece of DNA.
B. Related genes can all be regulated by the same environmental signal.
C. RNA polymerase can bind many places within a single gene.
D. Evolutionary gene transfer mechanisms can operate more efficiently.
E. A ribosome only needs to bind once to make all the genes into one large protein

Answer 13

Related genes can all be regulated by the same environmental signal

Question 14

A gene with a -10 and -35 site whose nucleotide sequence closely match the consensus sequence for an RNA polymerase sigma factor has no other regulatory protein binding sites nearby. This gene is . . .
A. probably under negative control
B. probably silent
C. probably constitutive
D. able to be translated more often than it is transcribed
E. impossible, since all genes must have regulatory protein binding sites

Answer 14

probably constitutive

Question 15

What is a “response regulator” in a two component regulatory system?
A. The environmental signal
B. The protein that phosphorylates itself in response to the environmental signal
C. A membrane protein that changes shape in the presence of the environmental signal
D. A protein that turns genes on or off in response to the environmental signal
E. A gene that is turned on or off in response to the environmental signal

Answer 15

A protein that turns genes on or off in response to the environmental signal

Question 16

Gene regulation achieved by moving a gene from a silent (cryptic) site to an expressed site near a promoter is called. . .
A. quorum sensing
B. response regulation
C. gene dispersal
D. two component regulation
E. cassette switching

Answer 16

cassette switching

Question 17

Most of the genes in prokaryotes are regulated together in operons. Why can’t eukaryotes have operons?
A. Eukaryotes use repressor proteins to regulate genes instead.
B. Prokaryotic mRNA is read 5’ to 3’, but eukaryotic ribosomes read 3’ to 5’.
C. Eukaryotic ribosomes can bind at only one place on each mRNA.
D. Eukaryotic mRNA cannot be transcribed and translated simultaneously.
E. Eukaryotic promoters do not orient RNA polymerase in any one direction

Answer 17

Eukaryotic ribosomes can bind at only one place on each mRNA.

Question 18

An INDUCIBLE gene is . . .
A. controlled by an activator protein
B. transcribed only in response to an environmental signal
C. regulated by a protein that binds downstream of its promoter
D. “on” more frequently than it is “off”
E. regulated by a small molecule that allows a repressor protein to bind to an operator

Answer 18

transcribed only in response to an environmental signal

Question 19

The araC gene is repressible by glucose and under positive control. A sketch of this gene being transcribed would best be represented by which of the following (triangle is glucose, circle is the regulatory protein)?

Answer 19

glucose absent to the left. arrow pointing to the right away from the circle (in between glucose and arrow)

Question 20

The zwf gene is constitutive. Which of the following is true?
A. There is always the same amount of zwf mRNA in the cell
B. There is always the same amount of Zwf protein in the cell
C. The rate of zwf mRNA production is always the same
D. zwf must have two competing regulatory proteins that cancel each other’s effects
E. zwf may possibly be a gene involved in amino acid biosynthesis

Answer 20

The rate of zwf mRNA production is always the same

Question 21

Which of the following is NOT true regarding cassette switching in bacteria?
A. It involves exchanging two genes and their promoters.
B. It can be used to alter bacterial surface proteins.
C. It occurs by the genetic mechanism called recombination.
D. It requires at least one copy of a silent gene somewhere in the chromosome.
E. It can result in production of mRNA from a gene that had not been expressed before

Answer 21

It involves exchanging two genes and their promoters

Question 22

Which of the following is true of activator proteins?
A. They are not used to control repressible genes.
B. They are only used in positive control regulatory systems.
C. They usually bind DNA downstream of a promoter sequence.
D. They usually bind RNA upstream of a Shine-Dalgarno sequence.
E. They can only bind DNA in the presence of environmental inducers

Answer 22

They are only used in positive control regulatory systems

Question 23

We would probably classify the regulation of a gene for respiratory chain proteins in a facultative anaerobe as . . .
A. constitutive
B. repressible
C. inducible
D. activatable
E. switchable

Answer 23

inducible

Question 24

One way pathogenic bacteria know that they’re in your body is that the temperature increases to 37 degrees C. Some bacteria sense this with a two-component regulatory system in which AerA is the sensor kinase and AerB the response regulator. What would be the most reasonable hypothesis about the function of this regulatory system?
A. AerA can be phosphorylated by AerB at 37 degrees C.
B. AerB activates transcription of AerA at 37 degrees C.
C. AerA congregates to high density in the cytoplasm at 37 degrees C.
D. AerB has a different, phosphorylatable, amino acid sequence at 37 degrees C.
E. AerA partially unfolds at 37 degrees C to expose a phosphorylation site.

Answer 24

AerA partially unfolds at 37 degrees C to expose a phosphorylation site.

Question 25

Which of the following best describes the function of a quoromone?
A. an indirect environmental inducer of certain genes
B. a regulator of proton pumping in the electron transport chain
C. a response regulator in a two-component regulatory system
D. a protein that binds upstream of a promoter to allow expression from a gene
E. a congregation of surface-attached bacteria that have become functionally specialized

Answer 25

an indirect environmental inducer of certain genes

Question 26

For some yeast to undergo sexual reproduction, a cell of mating type ‘a’ must join with a cell of mating type ‘.’ Mating type is determined by a single gene, and all yeast have both ‘a’ and ‘’ genes on their chromosomes. If there are not enough cells of one mating type (for example ‘a’), cells of the ‘’ mating type can turn themselves into ‘a’ cells so they can mate. This is an example of . . .
A. cloning
B. cassette switching
C. quorum sensing
D. induction
E. schizogony

Answer 26

cassette switching

Question 27

Which of the following is true of a prokaryotic operon containing two genes?
A. There will be a Shine-Dalgarno sequence at the 3’ end of each gene.
B. There will be one Shine-Dalgarno sequence at the 3’ end of the operon.
C. There will be a Shine-Dalgarno sequence at the 5’ end of each gene.
D. There will be one Shine-Dalgarno sequence at the 5’ end of the operon.
E. Operons are complex gene organizations found in eukaryotes, not in prokaryotes

Answer 27

There will be a Shine-Dalgarno sequence at the 5’ end of each gene

Question 28

We said that transcription (trs) and translation (trl) are “coupled” in prokaryotes. Can they be coupled in eukaryotes?
A. No, because trs and trl occur in different cell compartments in eukaryotes.
B. No, because eukaryotes must begin trl at the first AUG after the 3’ end of the mRNA.
C. No, because eukaryotes and prokaryotes have different coupling factors.
D. Yes, because wobble pairing occurs in both prokaryotes and eukaryotes.
E. Yes, because prokaryotes and eukaryotes use the same stop codons

Answer 28

No, because trs and trl occur in different cell compartments in eukaryotes

Question 29

The cdx gene is under negative control. What does this mean?
A. The cdx gene is repressed by environmental factors.
B. Transcription of cdx mRNA can be blocked by a repressor protein.
C. The cdx gene is “OFF” more of the time than it is “ON.”
D. The cdx gene has no promoter.
E. The product of the cdx gene is deleterious to the cell that produces it

Answer 29

Transcription of cdx mRNA can be blocked by a repressor protein

Question 30

RED HIGHLIGHTED
A gene with -10 and -35 sites that closely match the consensus sequence for an RNA polymerase sigma factor has no other regulatory protein binding sites nearby. This gene . . .
A. is able to be translated more often than it is transcribed
B. is probably silent
C. is probably inducible
D. would likely be represented by a yellow spot in any microarray experiment
E. would not be possible, since all genes must have regulatory protein binding sites

Answer 30

would likely be represented by a yellow spot in any microarray experiment

Question 31

The lac operon is . . .
A. repressed by glucose binding to the lac operon’s DNA
B. constitutive
C. inducible with two different inducers
D. both inducible and repressible
E. always transcribed, but not translated until lactose is present

Answer 31

inducible with two different inducers

Question 32

Some bacteria can detect contact with a surface and use this contact signal to “know” when to begin transcribing genes for a glycocalyx that helps them adhere to the surface. How would this regulation most likely work?
A. The surface would function like an activator protein to turn on the glycocalyx genes.
B. Contact would cause a negative control protein to become active and interact with glycocalyx genes.
C. DNA would bind to the surface, which would activate the glycocalyx genes.
D. A quoromone would alter one protein, which would transfer a phosphate to another protein that would affect glycocalyx genes.
E. Contact would distort a membrane protein, which would then transmit the signal to an activator protein.

Answer 32

Contact would distort a membrane protein, which would then transmit the signal to an
activator protein.

Question 33

About how many genes are expressed in a bacterium at any given time during its life cycle?
A. about 10
B. about 100
C. about 1000
D. about 5000
E. It depends how many promoters there are

Answer 33

about 1000

Question 34

Which of the following is true of a gene that is under positive control?
A. It is expressed when a regulatory protein binds to the DNA.
B. It is always regulated by an environmental inducer.
C. It is more frequently turned on than it is turned off.
D. It can only be turned on, never off.
E. It could encode a respiratory chain protein in an obligate aerobe

Answer 34

It is expressed when a regulatory protein binds to the DNA

Question 35

A repressible gene . . .
A. is always off, never on
B. is turned off more frequently than it is turned on
C. is regulated by a protein that binds downstream of the promoter
D. is turned off in response to an environmental signal
E. cannot be turned on by an activator protein

Answer 35

is turned off in response to an environmental signal

Question 36

A gene that constitutively produces cAMP is cloned into E. coli. How would the lac operon be regulated in this transgenic bacterium?
A. It would only be induced by lactose.
B. It would only be repressed by lactose.
C. It would be repressed by lactose and induced by glucose.
D. It would be induced by lactose and repressed by glucose.
E. It could never be turned on

Answer 36

It would only be induced by lactose

Question 37

A quorum sensing gene in Staphylococcus aureus is controlled by a 2-component regulatory system. What does this mean?
A. The gene is controlled by both an activator and a repressor.
B. A quoromone can induce the gene without crossing the cell membrane.
C. A quoromone enters the cell and phosphorylates a regulatory protein.
D. A transmembrane sensor protein phosphorylates the gene’s promoter.
E. The gene is controlled by both an inducer and a co-repressor

Answer 37

A quoromone can induce the gene without crossing the cell membrane

Question 38

When it is ON (transcribing a gene product), a repressible gene under positive control could be represented by which of the following?

Answer 38

Triangle on left then circle on line in middle with an arrow pointing to the right

Question 39

If a gene is under negative control, . . .
A. its regulatory protein binds between -10 and +1
B. it is always off
C. it is turned off by an environmental signal
D. its promoter sequence does not match the consensus well
E. its regulatory protein is made in an inactive form

Answer 39

its regulatory protein binds between -10 and +1

Question 40

Which of the following could best describe a two-component regulatory system?
A. A signal binds to a sensor kinase and then enters the cell to activate or repress genes.
B. A signal binds to a sensor, which then phosphorylates a repressing reporter.
C. A regulator is phosphorylated by a sensor that has received an environmental signal.
D. Binding of a signal to an intracellular kinase turns it into a regulatory repressor.
E. Binding of a signal to a sensing repressor causes it to phosphorylate a gene

Answer 40

A regulator is phosphorylated by a sensor that has received an environmental signal

Question 41

What is the purpose of cassette switching as a method of gene regulation?
A. To allow the cell to turn on multiple genes at the same time
B. To allow the cell to switch the promoter sequence between two genes
C. To allow the use of multiple sigma factors at the same time
D. To express gene variants that are otherwise silent
E. To allow the cell to respond to crowding by a high density of other cells

Answer 41

To express gene variants that are otherwise silent

Question 42

Which of the following is true of a three-gene operon under negative control?
A. It will have 3 repressor binding sites.
B. It will have 3 promoters.
C. It will be off (not transcribed) more frequently than it is on.
D. It will be regulated by a protein that blocks transcription.
E. It will be turned off in response to an environmental signal

Answer 42

It will be regulated by a protein that blocks transcription

Question 43

An inducible gene under positive control is transcribed (“turned on”) . . .
A. all the time, since “inducible” and “positive control” are both positive
B. whenever an environmental inducer binds to the promoter to initiate transcription
C. when an inducer modifies a regulatory protein to allow the regulatory protein to bind
D. whenever a regulatory protein is translated in the cell
E. when an environmental signal prevents a regulatory protein from binding

Answer 43

when an inducer modifies a regulatory protein to allow the regulatory protein to bind

Question 44

Which of the following is true regarding the lac operon?
A. It is induced by glucose and repressed by lactose.
B. It is induced by lactose and repressed by cAMP.
C. It is under positive control by cAMP and negative control by glucose.
D. It is under positive control by lactose and negative control by glucose.
E. It is induced by lactose and induced by cAMP.

Answer 44

It is induced by lactose and induced by cAMP.

Question 45

ll of the following are needed for cassette switching EXCEPT . . .
A. A response regulator
B. A gene variant without a promoter
C. Genetic recombination
D. Two different genes with the same promoter
E. Homology between silent and expressed genes

Answer 45

Two different genes with the same promoter

Question 46

The plasmid at the right is a cloning vector that contains an insert at the PvuII restriction sites as shown. You want to isolate the insert to clone it into a plant. What would be the easiest way to isolate the insert away from the rest of the vector?
A. Probe a library containing the clone and pick the colony recognized by the probe.
B. Digest the plasmid with PvuII and separate the insert from the vector by electrophoresis
C. Use micromanipulators to physically separate the insert by Atomic Force Microscopy
D. Digest the vector with a restriction endonuclease and make a library from the pieces
E. Use the Ti plasmid to separate the insert from the vector

Answer 46

Digest the plasmid with PvuII and separate the insert from the vector by electrophoresis

Question 47

One way to make a specific mutation in a piece of DNA is to . . .
A. use a primer with a mismatched nucleotide.
B. subject the DNA to an electric field.
C. clone the DNA into a cloning vector.
D. expose the DNA to ionizing radiation.
E. Digest the DNA with a restriction endonuclease

Answer 47

use a primer with a mismatched nucleotide

Question 48

A DNA library is plated on a petri dish, transferred to a membrane, and washed with a fluorescent probe. This procedure is called “____________”.
A. washing the library
B. cloning the library
C. screening the library
D. titering the clones
E. amplifying the clones

Answer 48

screening the library

Question 49

You have cloned the green fluorescent protein (GFP) gene next to the promoter for the proP gene. For what purpose have you done this?
A. To cause a mutation in the proP gene
B. To induce transcription of the proP gene
C. To make a library containing the GFP gene
D. To use GFP as a reporter gene to report proP promoter activity
E. This is the first step in cloning the proP gene into a foreign host

Answer 49

To use GFP as a reporter gene to report proP promoter activity

Question 50

What is the correct order for the three steps in the polymerase chain reaction (PCR), starting with a double stranded DNA sequence?
A. replicate the DNA, anneal primers, clone the DNA
B. anneal primers, replicate the DNA, denature the DNA
C. anneal probes, clone the DNA, isolate the clone
D. digest the DNA, run electrophoresis, probe the gel
E. denature the DNA, anneal primers, replicate the DNA

Answer 50

denature the DNA, anneal primers, replicate the DNA

Question 51

A piece of DNA 10 bases long that is tagged with a fluorescent label at the 3’ end could be used to. . .
A. initiate new DNA synthesis
B. locate a DNA sequence on a piece of filter paper
C. create a specific mutation in a gene
D. digest longer DNA sequences into short pieces
E. carry a cloned insert into a new host

Answer 51

locate a DNA sequence on a piece of filter paper

Question 52

DNA is extracted from a patient’s blood sample and denatured. Upstream and downstream primers specific for a Staphylococcus aureus gene are added, followed by DNA polymerase. The denaturing, priming and polymerase steps are repeated 40 times. The product of the reactions is run on an electrophoretic gel, but no bands are visible. Why not?
A. The denaturing step should have only been done once.
B. There should have been only one primer used.
C. The denaturing step should have been done after primer addition, not before.
D. RNA polymerase should have been used, since the template was DNA.
E. The patient is not infected with Staphylococcus aureus.

Answer 52

The patient is not infected with Staphylococcus aureus.

Question 53

The lacZ gene, whose colored product is easily seen, is inserted without its promoter into the middle of the coding region of the ptsG gene. The lacZ gene in this experiment is being used as a . . .
A. mutagenic primer
B. ribosome-binding site
C. probe
D. reporter gene
E. cloning vector

Answer 53

reporter gene

Question 54

Which of the following is NOT used when performing a Southern Blot?
A. Restriction digestion
B. Labeled probe
C. Sequencing primer
D. Electrophoresis
E. Filter (nitrocellulose) paper

Answer 54

Sequencing primer

Question 55

Cells of Bacillus anthracis that cause anthrax have in their cytoplasm a plasmid that is 5000 base pairs long. What technique would you use to determine whether a particular B. anthracis isolate had this plasmid?
A. restriction digestion
B. reporter gene fusion
C. DNA ligation
D. genetic cloning
E. electrophoresis

Answer 55

electrophoresis

Question 56

It is now easy to make mutations in any bacterial gene we choose. What technique can we use to make designer mutations?
A. Probes with sequence mismatches used as replication primers
B. Restriction digestion with two different enzymes
C. Colony hybridization with radioactive probes
D. Microarrays with labeled cDNA from two different species
E. Southern blotting of cloning vectors

Answer 56

Probes with sequence mismatches used as replication primers

Question 57

How do you use a DNA library?
A. You look up a specific sequence using a computer database
B. You cut the library out of a cell with restriction enzymes
C. You plate the library on petri dishes and screen it with a specific probe
D. You stretch the library out on a microscope slide and read it with AFM microscopes
E. You electrophorese the library and screen it by PCR

Answer 57

You plate the library on petri dishes and screen it with a specific probe

Question 58

A 2008 Nobel Prize was awarded to the discoverers of the GFP reporter gene. What is a reporter gene?
A. A gene used as a probe to report the position of another gene
B. A gene with a visible product used to report the activity of another gene’s promoter
C. A mutagenic gene used in cloning to make random mutations in other genes
D. A constitutive gene that is used to activate another gene that would otherwise be repressed
E. A gene used to isolate pieces of another organism’s chromosome to begin the process of gene cloning

Answer 58

A gene with a visible product used to report the activity of another gene’s promoter

Question 59

Which of the following is the easiest way to mutate a specific gene so that it is no longer transcribed?
A. Use a mismatched probe as a primer to mutate the promoter
B. Use a radioactive probe to target radiation damage to one gene
C. Cut out the gene with a restriction enzyme and ligate the rest of the chromosome back together
D. Move the gene’s ori closer to its terminator.
E. It is not yet possible to mutate a specific gene, though we’re getting close

Answer 59

Use a mismatched probe as a primer to mutate the promoter

Question 60

A DNA library is plated on a petri dish, transferred to a membrane, and washed with a fluorescent probe. What is the purpose of this procedure?
A. to wash impurities out of the library
B. to clone the library into a host
C. to find which clone contains a particular gene
D. to find how many clones there are in the library
E. to grow more clones and obtain a bigger library

Answer 60

to find which clone contains a particular gene

Question 61

A probe can be used in all of the following procedures EXCEPT . . .
A. joining restriction-digested DNA fragments
B. altering the DNA sequence of a gene
C. detecting a DNA sequence at a crime scene
D. amplifying the number of copies of a selected DNA fragment
E. diagnosing a genetic disease in a patient

Answer 61

joining restriction-digested DNA fragments

Question 62

Cells of the bacterium Bacillus anthracis that are pathogenic contain a plasmid whose size is about
6,000 base pairs. What is the best way to determine whether a particular B. anthracis cell is pathogenic?
A. Cell lysis followed by DNA gel electrophoresis
B. Cell lysis followed by restriction digestion and DNA gel electrophoresis
C. Use of a reporter gene inserted somewhere on the plasmid
D. Cloning of plasmid genes into a new host
E. Southern blotting using a plasmid sequence as a probe

Answer 62

Cell lysis followed by DNA gel electrophoresis

Question 63

The restriction endonuclease (RE) NheI hydrolyzes DNA after the first G in the palindromic sequence G│CTAGC, as indicated by the vertical line. The RE StyI hydrolyzes DNA at C│CTAGG. What would happen if you tried to ligate together a DNA fragment digested with NheI and one digested with StyI?
A. The DNA ligase would not recognize these sequences.
B. It would be impossible to form recombinant DNA using these fragments.
C. Recombinant DNA would form, and could be hydrolyzed again with NheI.
D. Recombinant DNA would form, but could not be hydrolyzed with either NheI or StyI.
E. Recombinant DNA would form, and could be hydrolyzed again with StyI

Answer 63

Recombinant DNA would form, but could not be hydrolyzed with either NheI or StyI

Question 64

You suspect that the glutamic acid (Glu) at a particular place in the sequence of the protein AmbE is important for ionic bond formation. You wish to design an experiment to test this hypothesis. What experiment would be most likely to give you the data you need? (You can use the genetic code from Question 17 if you need it.)
A. Cut the ambE gene with a restriction enzyme. If a GAA sequence is at the restriction digestion site, you will delete it by the digestion.
B. Make a library, and use a probe with the sequence CTT to find and delete the ambE gene.
C. Digest the DNA, electrophorese it, and use a probe containing a GAA sequence to clone the ambE gene.
D. Replicate the ambE gene using a primer containing the sequence TTT rather than CTT.
E. Use a microarray with oligonucleotides on some spots containing GAA sequences, and oligonucleotides on other spots containing CTT sequences

Answer 64

Replicate the ambE gene using a primer containing the sequence TTT rather than CTT.

Question 65

Arrange the following steps of the PCR (polymerase chain reaction) in order:
(1) primers are annealed to the 3’ ends of the gene to be copied
(2) DNA polymerase copies the DNA
(3) primers are annealed to the 5’ ends of the gene to be copied
(4) dsDNA is heated to 95oC
(5) RNA polymerase transcribes the DNA

Answer 65

4 - 1 - 2

Question 66

A mutant version of the abl gene is associated with tumor formation. This mutation creates an additional cleavage site for the restriction endonuclease BamHI, as shown. If a Southern blot is performed using the probe shown, what pattern of bands on the blot would be diagnostic for the
cancerous form of the abl gene?

Answer 66

Two lines

Question 67

Why would you “screen” a DNA library?
A. To find a gene whose sequence you don’t know
B. To separate the cloning vectors according to the size of the DNA insert
C. That’s how you insert a piece of DNA into a plasmid.
D. To enter the DNA sequence into a computer database
E. To find the colony that contains the gene you want to study

Answer 67

To find the colony that contains the gene you want to study

Question 68

You want to investigate why there is an amino acid with a positively-charged R-group in the active site of enzyme X. To do this, you decide to mutate the amino acid to one with a negatively-charged R-group. How would you make such a mutation?
A. Restriction digestion of enzyme X with two different endonucleases
B. Southern blotting of ligated cloning vectors containing the gene for enzyme X
C. Use a probe with a sequence mismatch to replicate a clone of the gene for enzyme X
D. Exposure of enzyme X to chemicals that would reduce its amino acids
E. Use radioactive probes for colony hybridization to a clone that expresses enzyme X

Answer 68

Use a probe with a sequence mismatch to replicate a clone of the gene for enzyme X

Question 69

Order the steps that are used to clone a specific gene.
1. insert a gene with a visible product into the gene we want to clone
2. screen clones for presence of a particular gene
3. transform host bacterial cells with cloning vector
4. ligate piece(s) of organism’s DNA into cloning vector
5. gel electrophoresis of DNA fragments and isolation of one fragment
6. digest organism’s DNA and cloning vector

Answer 69

6 - 5 - 4 - 3

Question 70

You read in a scientist’s lab notebook that a probe for the sequence 5’ GCGTAA 3’ was made with the sequence 5’ TTAGGC 3’. This was most likely . . .
A. done to create a sequence that a restriction endonuclease could recognize
B. done to allow the probe to attach to a slide in a microarray experiment
C. done to create a specific mutation in a replicated sequence
D. a mistake. The sequence is backwards for its intended purpose.
E. a mistake. G does not pair with G, so the probe will not function.

Answer 70

a mistake. G does not pair with G, so the probe will not function.

Question 71

Place in order the following steps used to create a cloning library and find a specific gene in the library. (Some of the steps may not be used.)
1. Clones are transferred to filter paper
2. Library is plated on agar
3. Clones are screened by colony hybridization
4. DNA is isolated and restricted
5. Cloned DNA is inserted into cloning host
6. DNA is ligated into cloning vector
7. Electrophoresis separates DNA

Answer 71

4 - 6 - 5 - 2 - 1 - 3

Question 72

What is a reporter gene?
A. Part of a two component regulatory system
B. A negative regulatory protein that binds to another gene’s operon
C. A vector used for oligonucleotide site-directed mutagenesis
D. A gene that is inserted into another gene to detect promoter activity
E. A gene with a consensus promoter that is used to define 100% promoter activity

Answer 72

A gene that is inserted into another gene to detect promoter activity

Question 73

Which parts of the cloning procedure can be replaced with which steps in the PCR? (RE = restriction endonuclease; e’phoresis = electrophoresis; hyb. = hybridization)
A. RE, e’phoresis and cloning vector replaced by primer hyb. and replication
B. RE and ligase replaced by plasmid vector and replication
C. e’phoresis and gene isolation replaced by denaturing, primer hyb. and replication
D. RE, e’phoresis and ligation replaced by primer hyb., denaturing and replication
E. e’phoresis and ligation replaced by denaturing plasmid vector and replication

Answer 73

e’phoresis and gene isolation replaced by denaturing, primer hyb. and replication

Question 74

Which of the following sequences is considered a palindrome?
A. 5’-GGAGG-3’
B. 5’-AGAAGA-3’
C. 5’-CGATCG-3’
D. 5’-CCCAAA-3’
E. 5’-TATAAT-3’

Answer 74

5’-CGATCG-3’

Question 75

Which of the following does NOT rely on the use of an oligonucleotide probe?
A. Screening a library for the presence of a particular gene
B. Performing site-directed mutagenesis on a particular gene
C. Replicating a specific gene by PCR
D. Examining gene transcription with a reporter gene
E. Locating a particular gene transferred from a gel to a filter paper

Answer 75

Examining gene transcription with a reporter gene

Question 76

A Southern Blot is being used to diagnose a particular mutation of the sequence TTTAAA to TTGAAA. The position of this mutation relative to a probe is shown below. Which is the correct depiction of mutant and normal bands on the blot?

Answer 76

one line

Question 77

Algae are primarily classified based on . . .
A. their means of motility
B. whether they produce toxins or not
C. the color of their photosynthetic pigments
D. their method of sexual reproduction
E. the host they usually infect

Answer 77

the color of their photosynthetic pigments

Question 78

Amoeba are typically motile by what means?
A. cytoplasmic streaming
B. cilia
C. flagella
D. slime jets
E. apicomplex attachment and retraction

Answer 78

cytoplasmic streaming

Question 79

istoplasmosis is a systemic fungal disease spread by what means?
A. mosquitoes as biological vectors
B. ingesting contaminated bread
C. going barefoot in communal showers and locker rooms
D. inhaling fungal spores in dust from bird droppings
E. sexual intercourse with an infected partner

Answer 79

inhaling fungal spores in dust from bird droppings

Question 80

The fungus in the picture at right belongs to what
reproductive class?
A. Ascomycetes
B. Zygomycetes
C. Basidiomycetes
D. Sporozoa
E. Yeast

Answer 80

Zygomycetes

Question 81

A flea can pick up eggs of the dog tapeworm on its legs and transmit them to a human host. This is an example of a _______ .
A. Mechanical vector
B. Biological vector
C. Cloning vector
D. Replication vector
E. Primary disease

Answer 81

Mechanical vector

Question 82

Which form of the pork tapeworm is especially dangerous, because it can migrate to the brain and form fatal abscesses?
A. Egg
B. Proglottid
C. Adult
D. Miracidium
E. Cysticercal Larva

Answer 82

Cysticercal Larva

Question 83

What type of organism is responsible for red tides?
A. a photosynthetic alga with red pigments
B. a halophilic bacterium with red pigments
C. a ciliated protozoan
D. a red colored helminth
E. a filamentous fungus with red hyphae

Answer 83

a photosynthetic alga with red pigments

Question 84

The LEAST serious human fungal infections . . .
A. are systemic
B. are superficial
C. are subcutaneous
D. are dimorphic
E. are inhaled as mold spores, but simply become yeast in the body.

Answer 84

are superficial

Question 85

The typhus bacterium is transmitted from human to human via the body louse. The louse picks up the bacterium, usually from fecal matter, and lands on another human, who scratches it under his skin because it itches. The louse in this scenario is a . . .
A. primary disease agent
B. secondary disease agent
C. cloning vector
D. biological vector
E. mechanical vector

Answer 85

mechanical vector

Question 86

What makes the pork tapeworm especially dangerous compared to other tapeworms?
A. The proglottids can break off and be passed to others in feces.
B. The host can inhale the eggs, which he then coughs up and swallows.
C. It can survive in salt water and at low temperatures.
D. Its cystecerci can penetrate the blood stream and cause brain abscesses.
E. Its trophozoites can migrate to the liver, which they eventually damage

Answer 86

Its cystecerci can penetrate the blood stream and cause brain abscesses

Question 87

Which microeukaryotes are classified based on their type of motility?
A. Protozoa
B. Algae
C. Fungi
D. Helminths
E. Archaea

Answer 87

Protozoa

Question 88

Fungal infections are particularly bad if the fungus is . . .
A. subcutaneous
B. a basidiomycete
C. Candida
D. Tinea
E. dimorphic

Answer 88

dimorphic

Question 89

A louse carries a bacterium to a human, who scratches the louse into his skin. The louse is an example of a . . .
A. Mechanical vector
B. Biological vector
C. Cloning vector
D. Replication vector
E. Primary disease

Answer 89

Mechanical vector

Question 90

Of the following, the most serious nematode infection is . . .
A. pinworm infestation of the colon
B. Ascaris growing in the small intestine
C. Hookworm burrowing into bare skin
D. Filarial worms living in the blood or lymph vessels
E. Tapeworm cysticerci in muscle tissue

Answer 90

Filarial worms living in the blood or lymph vessels

Question 91

Which of the following is NOT part of the Schistosome life cycle?
A. Cercarial larvae burrow into a human host
B. Miracidial larvae are ingested by a snail
C. Adult flukes mate in human blood vessels and lay eggs
D. Eggs are ingested by humans who eat contaminated food
E. Miracidial larvae hatch from eggs released in human feces

Answer 91

Eggs are ingested by humans who eat contaminated food

Question 92

If a bloom of the alga Pfiesteria were reported in a lake near where you lived, what would you expect to see in the news soon?
A. lots of cases of human intestinal poisonings
B. a report that the water had turned red
C. reports of lung infections from inhaling algal spores
D. reports of many dead fish
E. warnings that wild animals may have become infected

Answer 92

reports of many dead fish

Question 93

If you were in Milwaukee in 1993 and got cryptosporidial diarrhea, you most likely swallowed what form of this apicomplexan protozoan?
A. Trophozoite
B. Amoeba
C. Endospore
D. Oocyst
E. Proglottid

Answer 93

Oocyst

Question 94

Which of the following has been linked to carcinogenesis (cancer development)?
A. inhaling Histoplasma spores from mouse urine
B. ingesting Coccidioidal spores in bird feces
C. yeast infections in which the yeast Candida undergoes a transition to its mold form
D. cutaneous mycoses such as tinea corporis
E. exposure to aflatoxin from the fungus Aspergillus

Answer 94

exposure to aflatoxin from the fungus Aspergillus

Question 95

Which of the following is almost exclusively a mechanical disease vector rather than a biological vector?
A. Louse
B. Tick
C. House Fly
D. Mosquito
E. Flea

Answer 95

House Fly

Question 96

A common childhood infection, this relatively harmless intestinal worm can often be detected by dabbing clear tape around the anus and examining the tape for the adhering worms.
A. Ascaris
B. Hookworm
C. Filarial worm
D. Ringworm
E. Pinworm

Answer 96

Pinworm

Question 97

The motile form of a protozoan is usually . . .
A. called a trophozoite
B. harder to kill than the resting form
C. ciliated
D. surrounded by a tough cell membrane
E. called a schizogonite

Answer 97

called a trophozoite

Question 98

Algae are important to human health and disease because . . .
A. the ones that can change morphology cause serious lung infections
B. some algae can enter the brain and form cysts
C. they can serve as vectors for other diseases
D. some algae produce toxins that can cause illness if humans come in contact with them
E. they cause dysentery if humans drink water contaminated with them

Answer 98

some algae produce toxins that can cause illness if humans come in contact with them

Question 99

Which of the following is an example of a cutaneous fungal infection?
A. Histoplasmosis
B. Ringworm (Tinea corporis)
C. Dandruff (Pityriasis)
D. Hookworm
E. Cryptosporidium

Answer 99

Ringworm (Tinea corporis)

Question 100

Why is it significant for a fungus to be “dimorphic”?
A. It has two different sexual reproduction structures.
B. It can be classified in two different fungal species.
C. It is more likely to produce a toxin than other fungi.
D. It can appear as either a fungus or an alga.
E. It is more likely to cause systemic human disease than other fungi.

Answer 100

It is more likely to cause systemic human disease than other fungi.

Question 101

Which of the following is the best representation of the tapeworm infection cycle?
A. blood → lungs → cough up and swallow → feces
B. blood → liver → feces → water
C. contaminated food → intestine → eggs in feces
D. penetrate skin → blood → cysts in tissues (muscle and brain)
E. contaminated food → blood → liver → feces → fish

Answer 101

contaminated food → intestine → eggs in feces

Question 102

How do some algae cause paralytic shellfish poisoning in humans?
A. They colonize the digestive tract and overcome the native flora.
B. They produce larvae that can invade the brain and cause abscesses.
C. They differentiate into motile zoospores that enter the body through damaged skin.
D. They produce a neutotoxin that is ingested when people eat shellfish.
E. They are mechanical vectors that transmit diseases from other microbes

Answer 102

They produce a neutotoxin that is ingested when people eat shellfish.

Question 103

An investigator with the city water department finds trophozoites of a sporozoan in a water sample. What can you deduce from this?
A. She could have identified them when she saw the apicomplexes.
B. She could have observed them by using a stain that was specific for flagella.
C. She could identify what kind of sporozoan it was by examining its photosynthetic pigment.
D. She should warn people in the city about a possible outbreak of amoebic dysentery.
E. She shouldn’t be too concerned because trophozoites are easy to kill.

Answer 103

She could have identified them when she saw the apicomplexes.

Question 104

What sort of medical problem is caused by pinworms?
A. Blockage of blood vessels in the heart, leading to heart failure.
B. Taking essential nutrients from the infected person, causing malnutrition.
C. Intense itching around the anus as the worms crawl from the intestine.
D. Liver damage from an immune response to the worm eggs in the liver.
E. Growth of a massive ball of worms can block and eventually rupture the intestine.

Answer 104

Intense itching around the anus as the worms crawl from the intestine

Question 105

How do you typically get schistosomiasis?
A. by eating food contaminated with schistosome proglottids
B. by coming into contact with fleas that carry schistosome eggs on their leg hairs
C. by wading or standing in water that contains cercarial larvae
D. by going barefoot in soil contaminated with miracidial larvae
E. by eating uncooked or undercooked pork products

Answer 105

by wading or standing in water that contains cercarial larvae

Question 106

Which of the following statements about algae is correct?
A. Algae don’t colonize humans, but do produce neurotoxins.
B. Algae have a life cycle with two very different forms.
C. Algae divide by schizogony.
D. All algae are motile by cytoplasmic streaming.
E. Algae are classified based on how they reproduce

Answer 106

Algae don’t colonize humans, but do produce neurotoxins.

Question 107

The picture at the right shows a . . .
A. fungal spore
B. yeast cell
C. ciliated protozoan
D. coccoidal bacterium with pili
E. sporozoan

Answer 107

ciliated protozoan

Question 108

A food microbiologist looked at the loaf of bread shown hereand decided to examine the contaminant microscopically. He observed the structure shown in the inset picture. How would he classify the organism that is contaminating the bread?
A. a filamentous algae
B. a rod-shaped bacterium with endospores
C. a dimorphic fungus
D. a zygomycete fungus
E. a basidiomycete fungus

Answer 108

a zygomycete fungus

Question 109

A patient from Mexico went to the hospital with seizures
and loss of consciousness. A brain X-ray is shown at right.
The X-ray technician circled some interesting lesions. What did the doctor conclude?
A. The patient had been standing in water with
schistosome contamination.
B. The patient had likely been consuming undercooked pork.
C. The patient had likely engaged in disreputable practices to try to lose weight.
D. The patient probably lived in an area contaminated with bird fecal matter.
E. The patient was likely infected with a transforming virus

Answer 109

The patient had likely been consuming undercooked pork.

Question 110

A disease called Paralytic Shellfish Poisoning is caused by. . .
A. an algal toxin
B. an algal zoospore
C. a fungal toxin
D. a fungal spore
E. larvae of a fish tapeworm

Answer 110

an algal toxin

Question 111

Which of the following is a protozoan without any form of motility at all?
A. an apicomplexan
B. an amoeba
C. a Giardia trophozoite
D. a Cryptosporidium cyst
E. a sporozoan

Answer 111

a Cryptosporidium cyst

Question 112

Ringworm (Tinea corporis) would most accurately be described as . . .
A. a nematode infection of the intestine
B. an allergic reaction to a flat worm infestation of the skin
C. skin colonization by a cutaneous fungus
D. a respiratory infection acquired by inhaling spores of a dimorphic fungus
E. diarrhea caused by infection with a flagellated protozoan

Answer 112

skin colonization by a cutaneous fungus

Question 113

my’s foot has developed the very itchy and inflamed skin lesion shown at right. How did Amy most likely acquire this infection?
A. She ate undercooked pork.
B. Schistosome eggs penetrated her skin.
C. She came in contact with a protozoal toxin.
D. She inhaled the spores of a cutaneous fungus.
E. Hookworm larvae penetrated the skin of her foot.

Answer 113

Hookworm larvae penetrated the skin of her foot.

Question 114

What role does a snail play in the transmission of the disease Bilharzia?
A. The snail is the mechanical vector on which the Bilharzia parasite lives.
B. The snail is the biological vector in which cercarial larvae develop.
C. Humans eat snails contaminated with Bilharzia proglottids.
D. Cysticerci are transmitted to humans by the bite of a snail.
E. Snail defecation releases miracidial larvae into a body of water.

Answer 114

The snail is the biological vector in which cercarial larvae develop.

Question 115

An organism with an apicomplex is called . . .
A. an amoeba
B. a tapeworm
C. an alga
D. a fungus
E. a sporozoan

Answer 115

a sporozoan

Question 116

Ringworm is a . . .
A. nematode
B. tapeworm
C. cutaneous fungus
D. fluke
E. filarial worm

Answer 116

cutaneous fungus

Question 117

Your dog has fleas. Why might you not want to let it play with your kids?
A. Fleas can be a mechanical vector for tapeworm eggs.
B. Fleas can cause disease.
C. Fleas may burrow under the skin and cause allergic reactions.
D. Fleas may be a biological vector for pinworm eggs.
E. Flea larvae may form cysts that can invade the brain.

Answer 117

Fleas can be a mechanical vector for tapeworm eggs.

Question 118

The person shown in the picture at the right is infected with. . .
A. Ascaris worms
B. Hookworm
C. A systemic fungus
D. Pinworms
E. Trichinella

Answer 118

Hookworm

Question 119

Which stage of the schistosome life cycle causes liver damage? Which stage needs to enter a snail for further development?
A. cercaria ; adults
B. eggs ; miracidia
C. eggs ; cercaria
D. adults ; eggs
E. cercaria ; miracidia

Answer 119

eggs ; miracidia

Question 120

Among the more dangerous algae are those that . . .
A. have an apicomplex
B. undergo a dimorphic life cycle
C. are vectors to carry other diseases
D. produce saxitoxins
E. form multiple larvae

Answer 120

produce saxitoxins

Question 121

Which of the following best describes a cutaneous mycosis?
A. It is often fatal if not treated quickly.
B. It usually produces no symptoms in the affected patient.
C. It only grows on top of the skin; it does not penetrate any skin layers.
D. It usually begins by inhaling fungal spores.
E. It is itchy and annoying, but is not usually dangerous.

Answer 121

It is itchy and annoying, but is not usually dangerous.

Question 122

Which of the following is an example of a biological vector?
A. A fly carries bacterial spores on its legs
B. A louse carries bacteria which enter the skin when scratched
C. A flea must take a blood meal to transmit an infection
D. A mite causes inflammation when it burrows into skin
E. A worm attaches to the intestinal lining and releases cysts

Answer 122

A flea must take a blood meal to transmit an infection

Question 123

A nematode that lives in blood vessels and is considered a serious health problem would most likely be a/an . . .
A. Ascaris worm
B. Filarial worm
C. Pinworm
D. Cysticercus
E. Ringworm

Answer 123

Filarial worm

Question 124

Which of the following would NOT be used to classify a virus?
A. presence or absence of matrix protein
B. type of nucleic acid
C. single or double stranded nucleic acid
D. shape of nucleocapsid
E. presence or absence of envelope

Answer 124

presence or absence of matrix protein

Question 125

You get a “cold sore” on your lip. This is an example of a latent viral infection. A year later, you get another cold sore in the same place. How did this second infection arise?
A. You were exposed a second time to the infectious agent.
B. You were exposed again, but to a different virus that also causes cold sores.
C. The virus was released from your system for the whole year, but in amounts too low to cause symptoms.
D. The virus was “hiding” in your cells until it was reactivated.
E. The virus titer was continually increasing for the entire year, until it finally was enough to cause another cold sore

Answer 125

The virus was “hiding” in your cells until it was reactivated.

Question 126

How can a retroviral provirus cause cancer?
A. It can lyse enough cells to cause a tumor.
B. It can cause a latent infection which can develop into cancer.
C. It can carry the infectious agent for cancer in its capsid.
D. It can bud from the cell and metastasize to other cells.
E. It can insert into and disrupt a tumor suppressor gene.

Answer 126

It can insert into and disrupt a tumor suppressor gene.

Question 127

Why is it notoriously difficult to develop a vaccine against segmented viruses?
A. They do not activate the adaptive immune response.
B. They have a capsule that can fragment into small pieces.
C. They undergo genetic reassortment to produce new surface proteins.
D. They have a longer latent period than unsegmented viruses.
E. They are usually RNA viruses, and you can’t vaccinate against RNA

Answer 127

They undergo genetic reassortment to produce new surface proteins

Question 128

What is one way plant viruses differ from animal viruses?
A. They are all RNA viruses.
B. Neither membrane fusion nor endocytosis can get them into a plant cell.
C. They have a special outer layer called the plasmodesmata.
D. They can’t cause tumors; animal viruses can.
E. They do not carry any nucleic acid, just protein

Answer 128

Neither membrane fusion nor endocytosis can get them into a plant cell.

Question 129

How are prions infectious?
A. They are just RNA, and when they get into cells, the RNA replicates.
B. They contain their own replication enzymes.
C. They take over the host’s replication system to make more copies of themselves.
D. They act as “folding templates” to misfold other proteins.
E. They remain latent in neurons and cause infection when reactivated.

Answer 129

They act as “folding templates” to misfold other proteins

Question 130

A virus cannot have within its capsid . . .
A. single stranded DNA
B. double stranded RNA
C. both DNA and RNA
D. replication enzymes
E. any nucleic acids

Answer 130

both DNA and RNA

Question 131

A virus that enters a host cell by membrane fusion rather than by endocytosis . . .
A. brings its envelope glycoproteins into the cell with it
B. must be an enveloped virus
C. does not need to be uncoated once it enters the cell
D. must carry a phospholipid-digesting enzyme into the cell with it
E. will always replicate its nucleic acid in the host cell’s nucleus

Answer 131

must be an enveloped virus

Question 132

A latent virus . . .
A. uses reverse transcriptase
B. causes no cell damage
C. replicates very slowly over a long time period
D. inserts as a provirus into the host DNA
E. results in a permanently positive direct ELISA test

Answer 132

causes no cell damage

Question 133

Place the steps in the replication of an acute virus in the correct order.
A. DNA replication, budding, membrane fusion, uncoating, assembly
B. membrane fusion, uncoating, DNA replication, assembly, budding
C. uncoating, DNA replication, membrane fusion, assembly, budding
D. budding, DNA replication, assembly, uncoating, membrane fusion
E. DNA replication, uncoating, assembly, membrane fusion, budding

Answer 133

membrane fusion, uncoating, DNA replication, assembly, budding

Question 134

A chronic virus . . .
A. uses reverse transcriptase
B. usually lyses an infected host cell quickly
C. causes a new infection after a long time without symptoms
D. replicates very slowly over a long time period
E. continually buds from the host cell for a long time period

Answer 134

continually buds from the host cell for a long time period

Question 135

How would you detect the presence of a provirus in a host cell?
A. Perform a Southern blot on the host’s DNA and probe with a viral DNA probe
B. Examine the host for viral diseases such as cancer
C. Look for viral coat proteins when the host lyses
D. Examine the host cell DNA by electrophoresis to look for viral plasmids
E. Use a reporter gene to look for induction of the host’s reverse transcriptase gene

Answer 135

Perform a Southern blot on the host’s DNA and probe with a viral DNA probe

Question 136

On this diagram of an enveloped icosahedral virus, where is the capsid?

Answer 136

pointing on hexagon

Question 137

The Baltimore classification system for viruses is based on. . .
A. capsid shape
B. presence of a lipid envelope
C. how the nucleic acid is replicated
D. the city where the virus was discovered
E. how the virus enters the host cell

Answer 137

how the nucleic acid is replicated

Question 138

Genetic reassortment is a way for . . .
A. RNA viruses to replicate
B. segmented viruses to increase their variability
C. naked viruses to assemble their nucleic acid before budding from their host cell
D. viral polyproteins to be separated into individual proteins
E. prions to associate with the proteins they will eventually misfold

Answer 138

segmented viruses to increase their variability

Question 139

This plant is most likely infected with a . . .
A. mosaic virus
B. stunt virus
C. wilt virus
D. prion
E. phage

Answer 139

mosaic virus

Question 140

How can plant viruses spread through a plant?
A. They bud from one cell and enter another by membrane fusion.
B. They are released from one cell by exocytosis and enter another by endocytosis.
C. They pass between cells through communication channels called plasmodesmata.
D. They lyse one cell and are taken up into another after binding to a receptor.
E. Bacteria serve as biological vectors to carry them throughout the plant’s xylem

Answer 140

They pass between cells through communication channels called plasmodesmata

Question 141

Which of the structures is present in all viruses?

Answer 141

E - sides of hexagon

Question 142

Viruses can be classified by all of the following EXCEPT . .
A. shape of the lipid envelope
B. DNA or RNA replication intermediates
C. type of nucleic acid
D. capsid morphology
E. whether or not the nucleic acid is segmented

Answer 142

shape of the lipid envelope

Question 143

Varicella-Zoster virus (VZV) can be seen as a plasmid in infected cells from a person who doesn’t show symptoms of virus infection. These infected cells do not contain any viral proteins. Which of the following is true?
A. VZV could reactivate and the person could show symptoms later.
B. VZV is an example of a chronic virus.
C. VZV could interrupt tumor suppressor genes and cause cancer.
D. The person suffered VZV symptoms earlier, but will show no further symptoms.
E. The plasmid may soon become a provirus

Answer 143

VZV could reactivate and the person could show symptoms later.

Question 144

Which of the following is true for plant viruses?
A. The plant does not usually show any symptoms of infection.
B. The virus enters the cell through pre-existing holes, rather than by membrane fusion.
C. Plant infections are usually acute, rather than chronic.
D. They may cause other symptoms, but cannot transform plant cells to form a tumor.
E. They usually contain protein, but no nucleic acid.

Answer 144

The virus enters the cell through pre-existing holes, rather than by membrane fusion.

Question 145

Which of the following represents the location of a capsomere?

Answer 145

A - sides of hexagon

Question 146

Viruses in Baltimore Group V have negative stranded RNA genomes. Which of the following must be true?
A. They must all be naked viruses.
B. Their nucleic acid must be segmented.
C. They must translate a polyprotein and then cleave it.
D. Their nucleic acid can be translated as soon as the virus uncoats.
E. They must carry a polymerase as a virus-associated enzyme.

Answer 146

They must carry a polymerase as a virus-associated enzyme.

Question 147

How is the membrane assembled in an enveloped virus?
A. Lipids synthesized by the virus assemble with the nucleocapsid in the cytoplasm.
B. Virally-synthesized lipids insert in the host membrane and are added to the budding virus.
C. Lipids are synthesized as polymers and then broken into their monomers during assembly.
D. The membrane is simply the host cell membrane that surrounds the virus during budding.
E. Lipids are synthesized in the cytoplasm and added to the viral nucleic acid in the nucleus.

Answer 147

The membrane is simply the host cell membrane that surrounds the virus during budding.

Question 148

To monitor the course of a viral infection, a doctor samples a patient’s blood and tests for the presence of a viral matrix protein. Over the course of several years, the results are shown in the graph at the right. What can you conclude about this virus?
A. It causes a latent infection.
B. It causes a chronic infection.
C. It causes an acute infection.
D. It is a retrovirus.
E. It probably lyses the host’s cells as it exits

Answer 148

It causes a chronic infection.

Question 149

Can viruses that don’t have a proviral form cause cancer?
A. Yes, if they contain a capsid protein that causes cancer.
B. Yes, if they are latent and relapse often enough.
C. Yes, if they carry a cell replication gene with a strong promoter.
D. No. It is the proviral protein that causes cancer.
E. No. Only by integrating in the middle of a gene can a virus cause cancer

Answer 149

Yes, if they carry a cell replication gene with a strong promoter.

Question 150

Given how they infect cells, plant viruses have somewhat different anatomy from animal viruses. Which of the following is true?
A. Plant viruses do not have capsid proteins.
B. Plant viruses do not have nucleic acid.
C. Plant viruses are composed of tiny RNA molecules and nothing else.
D. Plant viruses have many more spike proteins than animal viruses do.
E. Plant viruses are almost always naked.

Answer 150

Plant viruses are almost always naked.

Question 151

How do plant viruses typically enter plant cells?
A. Through holes or pores in the cell wall
B. By budding from one cell into another
C. By receptor-mediated endocytosis
D. By fusion of viral envelope and plant cell membrane
E. They are injected by bacteria with Type III secretory systems

Answer 151

Through holes or pores in the cell wall

Question 152

Which part(s) of the virus come(s) only from the host cell?
A. the part labeled D
B. the part labeled B
C. the parts labeled A and F
D. the parts labeled B, C and D
E. No part of a virus comes only from the host cell

Answer 152

part labeled D - outer membrane

Question 153

Which part of the virus can be either icosahedral or helical?
A. The entire virus is either helical or icosahedral.
B. the part labeled A
C. the part labeled C
D. the part labeled D
E. the part labeled E

Answer 153

part labeled E - outer membrane

Question 154

What can enveloped viruses do that naked viruses cannot?
A. attach to specific host cell receptors
B. carry viral polymerase proteins within the capsid
C. translate RNA into proteins
D. be released from host cells by budding
E. survive dry conditions for a longer decimal reduction time

Answer 154

be released from host cells by budding

Question 155

Viruses in the Herpes family are examples of latent viral infections. Which of the following would be true one year after a person is infected by a Herpesvirus?
A. Neither DNA nor capsomeres from Herpes could still be detected in the person.
B. Small amounts of both DNA and capsomeres from Herpes could be detected in the person.
C. Viral capsomeres could be detected in the person, even though viral DNA could not.
D. Viral DNA could be detected in the person, even though viral capsomeres could not.
E. Lots of both DNA and capsomeres from Herpes could be detected in the person

Answer 155

Viral DNA could be detected in the person, even though viral capsomeres could not

Question 156

Animal viruses, but not plant viruses, commonly do which of the following?
A. cause tumors
B. enter a host cell by membrane fusion
C. travel throughout a host tissue
D. be transmitted to a host by an insect vector
E. change the pigmentation of a host’s tissue

Answer 156

enter a host cell by membrane fusion

Question 157

Which part of this virus is derived entirely from a part of the host cell?
A. A
B. B
C. C
D. D
E. No part of this virus is derived entirely from host cell material.

Answer 157

No part of this virus is derived entirely from host cell material.

Question 158

What is the difference between a virus in Baltimore group I and one in group II?
A. Presence or absence of an envelope
B. Whether or not the nucleic acid is segmented
C. The shape of the viral capsid
D. The mechanism used to replicate the nucleic acid
E. Whether the virus is classed as a prokaryote or a eukaryote

Answer 158

The mechanism used to replicate the nucleic acid

Question 159

Which is the unique step in the life cycle of retroviruses?
A. Production of an RNA/DNA hybrid during replication
B. Entry into the cell by endocytosis
C. Use of a polyprotein protease during assembly
D. Viral latency within host cells
E. Mechanism by which new virions are released from a host cell

Answer 159

Production of an RNA/DNA hybrid during replication

Question 160

Epstein-Barr virus is responsible for many tumors, but it does not exist as a provirus. How can it cause tumor formation?
A. It can integrate into and disrupt a tumor suppressor gene.
B. It can insert into and disrupt an oncogene’s promoter.
C. It can carry its own unregulated copy of an oncogene.
D. It can lyse too many host cells by prolonged budding over a long time.
E. It can produce interferon that transforms the host into a tumor cell.

Answer 160

It can carry its own unregulated copy of an oncogene.

Question 161

What happens after prions cause protein misfolding?
A. The growth of the infected host can become stunted.
B. Neurons can proliferate uncontrollably, resulting in a tumor.
C. Protein synthesis in a host cell is inhibited.
D. Neuron death leads to brain tissue becoming porous.
E. Death of infected cells leads to inflammation of tissues.

Answer 161

Neuron death leads to brain tissue becoming porous.

Question 162

On the diagram of a virus at the right, which is the matrix protein?

Answer 162

C - inner part of outer membrane

Question 163

An antiviral agent inhibits the formation of a provirus. What would be a consequence of that?
A. None of the viral capsomeres would be found within the host cell.
B. The drug would reduce the likelihood of tumor formation by this virus.
C. The drug would also prevent membrane fusion by this virus.
D. The virus would not be able to replicate its nucleic acid at all.
E. None of the viral nucleic acid would be found inside the host cell

Answer 163

The drug would reduce the likelihood of tumor formation by this virus.

Question 164

EBV is a type of virus that can cause a latent infection. Electron micrographs reveal small ring-
shaped molecules in the nuclei of infected host cells. Which of the following is true about a latent EBV
infection?
A. More copies of the virus are being made all the time.
B. The rings eventually integrate into the host cell’s chromosome.
C. The rings are non-replicating copies of the viral nucleic acid.
D. The patient continues to show symptoms of infection, even without viral replication.
E. The rings will eventually be cleared from the nuclei by the immune system

Answer 164

The rings are non-replicating copies of the viral nucleic acid

Question 165

which of the following would NOT be a good bacterial target for an antibiotic with a high therapeutic index?

A. protein synthesis
B. lipid synthesis
C. DNA synthesis
D. peptidoglycan synthesis
E. folic acid synthesis

Answer 165

lipid synthesis

Question 166

what is the mode of action of the antiviral medication aceyclovir?

A. protein synthesis inhibitor
B. inhibits viral assembly
C. nucleoside analog DNA/RNA synthesis inhibitor
D. non-nucleoside reverse transcriptase inhibitor
E. inhibits uncoating of the virus

Answer 166

nucleoside analog DNA/RNA synthesis inhibitor

Question 167

what destroys cell membrane, therefore has low therapeutic index?
A. vancomycin
B. Tetracycline
C. trimethoprim
D. Cephalosporins
E. Polymyxin

Answer 167

polymyxin

Question 168

what is a protein synthesis inhibitor?
A. vancomycin
B. Tetracycline
C. trimethoprim
D. Cephalosporins
E. Polymyxin

Answer 168

tetracycline

Question 169

what prevents viral entry and uncoating?

A. Amantadine (symmetrel)
B. Synercid
C. Acyclovir
D. Tamiflu (oseltamivir)
E. Protease inhibitor

Answer 169

amantadine (symmetrel)

Question 170

what is a nucleoside analog that does not allow continued DNA or RNA synthesis?
A. Amantadine (symmetrel)
B. Synercid
C. Acyclovir
D. Tamiflu (oseltamivir)
E. Protease inhibitor

Answer 170

acyclovir

Question 171

A cutaneous case of tinea corporis could best be treated with . . .
A. Penicillin
B. Fluconazole
C. Ivermectin
D. Mupirosin
E. Bacitracin

Answer 171

fluconazole

Question 172

Which of the following would you expect to be true when comparing a first generation
antimicrobial drug with a second generation drug?
A. The first generation drug would have a broader activity spectrum.
B. The second generation drug would have a higher therapeutic index.
C. The second generation drug would be more likely to be the substrate of a bacterial
efflux pump.
D. The second generation drug would likely only be useful topically.
E. The first generation drug would have a lower MIC.

Answer 172

the second generation drug would have a higher therapeutic index

Question 173

The first antibiotic to be used commercially is a competitive inhibitor of bacterial folic acid
biosynthesis. What antibiotic is this?
A. Penicillin
B. Cephalosporin
C. Tetracycline
D. Polymyxin
E. Sulfanilamide

Answer 173

Sulfanilamide

Question 174

One of the antifungal drugs that is the least toxic in humans interferes with fungal ergosterol
biosynthesis. It is frequently taken orally.
A. Amphotericin B
B. Griseofulvin
C. Metronidazole
D. Fluconazole
E. Amantadine

Answer 174

Fluconazole

Question 175

Why has the existence of R-plasmids made antibiotic overuse dangerous?
A. Using antibiotics creates R-plasmids more rapidly.
B. Using antibiotics makes it more likely for R-plasmids to transfer between cells.
C. Using antibiotics makes it more likely for R-plasmids to pick up bacterial genes.
D. Many bacteria contain multiple toxin genes on R-plasmids.
E. Using one antibiotic can select for growth of bacteria with multiple drug resistance.

Answer 175

Using one antibiotic can select for growth of bacteria with multiple drug resistance.

Question 176

Which of the following would be a desirable property in an antimicrobial agent?
A. It has a low therapeutic index.
B. It is activated only in infected cells.
C. It initiates an immune response in the patient.
D. It targets phospholipid biosynthesis.
E. It must be administered intravenously

Answer 176

It is activated only in infected cells.

Question 177

Which of the following is NOT used as a target for antiviral agents?
A. nucleic acid synthesis
B. receptor binding
C. proteolysis of a polyprotein
D. viral budding from a host cell
E. viral folic acid metabolism

Answer 177

viral folic acid metabolism

Question 178

What is the mode of action of the fluoroquinolone antibiotics such as ciprofloxacin?
A. inhibit protein synthesis
B. inhibit cell wall cross-linking
C. collapse the bacterial PMF
D. interfere with the action of DNA gyrase
E. interfere with the assembly of the cell membrane

Answer 178

interfere with the action of DNA gyrase

Question 179

One advantage of the Kirby-Bauer test compared to MIC testing is that the Kirby-Bauer
test. . .
A. is more accurate
B. can determine the MIC for multiple antibiotics simultaneously
C. is cheaper and easier to perform in a clinical setting
D. provides results in minutes rather than the hours required for MIC testing
E. can determine the toxic dose of an antibiotic as well as the therapeutic dose

Answer 179

is cheaper and easier to perform in a clinical setting

Question 180

Which of the following targets for antimicrobial drugs would be associated with the LOWEST
therapeutic index?
A. Bacterial cell membrane
B. Viral uncoating
C. Folate metabolism
D. Bacterial protein synthesis
E. Bacterial PMF maintenance

Answer 180

Bacterial cell membrane

Question 181

What is the mode of action of rifampin?
A. inhibits ergosterol biosynthesis
B. looks like a nucleoside, and inhibits DNA replication
C. inhibits bacterial RNA polymerase
D. inhibits peptidoglycan crosslinking
E. inhibits bacterial DNA gyrase

Answer 181

inhibits bacterial RNA polymerase

Question 182

Which of the following genes would you be surprised to find on an R-plasmid?
A. structural genes for mating pili
B. genes for a polyprotein protease
C. genes for a Type I secretion system
D. mutant genes for ribosomal proteins
E. genes for an enzyme that hydrolyzes this structure:

Answer 182

genes for a polyprotein protease

Question 183

A student who frequently goes caving in southern Indiana presents
with respiratory distress. An X-ray shows lung granulomas. The sample
shown at the right was isolated from bronchial washes. The patient was
prescribed fluconazole. What is the purpose of this medicine?
A. To inhibit mycolic acid synthesis
B. To prevent ergosterol synthesis in the fungus
C. To prevent the bacterium from secreting a toxin
D. To prevent the virus from infecting new cells
E. To inhibit the glycosidic bonds in the cell wall

Answer 183

To prevent ergosterol synthesis in the fungus

Question 184

Which of the following is a desirable property for a new antibiotic to have?
A. It should be acid-sensitive.
B. It should be able to be recognized by antibodies.
C. It should have a high therapeutic index.
D. It should be strong enough to “clean out” (kill) the native flora as well as the infection.
E. It should be bacteriolytic for Gram negative bacteria.

Answer 184

It should have a high therapeutic index.

Question 185

Usually antibacterial, antiviral and antifungal agents target different processes, but there is one
process that can be targeted by all three agents. It is . . .
A. cell wall synthesis
B. metabolism
C. neuraminidase function
D. nucleic acid replication
E. ribosome assembly

Answer 185

nucleic acid replication

Question 186

A traveler to Brazil is given a prescription for Chloroquine. Why?
A. He doesn’t want to get bacterial diarrhea from the food he will eat.
B. He probably has a viral infection that he might spread to other people on the plane.
C. He may be exposed to malaria while in Brazil, and this will prevent an infection.
D. If he plans to go barefoot on the beach, this will prevent him from getting schistosomiasis.
E. Coccidioidomycosis is endemic to Brazil, and he will probably inhale the spores.

Answer 186

He may be exposed to malaria while in Brazil, and this will prevent an infection.

Question 187

Tamiflu (oseltamivir) works by . . .
A. inhibiting DNA replication
B. inhibiting folic acid biosynthesis
C. inhibiting ergosterol biosynthesis
D. inhibiting a viral protease
E. preventing release of viruses from infected cells

Answer 187

preventing release of viruses from infected cells

Question 188

Tetracycline is very commonly used in the US. It kills bacteria by . . .
A. inhibiting cell wall cross-linking
B. preventing the attachment of tRNA to the A site of the ribosome
C. inhibiting DNA gyrase
D. hydrolyzing the beta-1,4 bonds in peptidoglycan
E. collapsing the PMF that bacteria use to generate energy

Answer 188

preventing the attachment of tRNA to the A site of the ribosome

Question 189

An E-test would be very useful when treating a Pseudomonas infection. Why?
A. R-plasmids and antibiotic resistance are very common in Pseudomonas
B. to figure out whether the patient is making antibodies against Pseudomonas
C. to determine how the bacterium was transmitted epidemiologically
D. to check if the patient might be allergic to a particular antibiotic
E. to check for the potentially dangerous IgE protease that Pseudomonas produces

Answer 189

R-plasmids and antibiotic resistance are very common in Pseudomonas

Question 190

Which of the following properties might be expected in a second generation (GEN2) antibiotic, but
not in a first generation one?
A. The GEN2 would be more acid resistant than the GEN1.
B. The GEN2 would be more likely to be a hapten than the GEN1.
C. The GEN2 would suppress native flora in addition to pathogens.
D. The GEN2 would be bacteriostatic, where the GEN1 was only bacteriocidal.
E. The GEN2 would target cell membranes instead of cell walls.

Answer 190

The GEN2 would be more acid resistant than the GEN1.

Question 191

Acyclovir is commonly prescribed to treat Herpes virus infections. How does it work?
A. It interferes with viral envelope synthesis.
B. It is a nucleoside analog that inhibits viral replication.
C. It is a protease inhibitor that interferes with viral assembly.
D. It interferes with the neuraminidase that viruses need to bind to host cells.
E. It inhibits the exocytosis process that releases new viruses from a host cell.

Answer 191

It is a nucleoside analog that inhibits viral replication.

Question 192

Which of the following is a commonly used, but highly toxic antifungal agent?
A. Streptogramin
B. Cephazolin
C. Amantadine
D. Metronidazole
E. Amphotericin B

Answer 192

Amphotericin B

Question 193

Ivermectin is commonly used to treat . . .
A. malaria
B. systemic fungal infections
C. helminth infections
D. MRSA
E. Influenza

Answer 193

helminth infections

Question 194

When performing a Kirby-Bauer test on a particular bacterium, 8 antibiotic disks are placed on a
lawn of the bacteria. It is found that there are no clear zones around any of the antibiotic disks. Which
of the following is likely to be true?
A. An infection with this bacterium should be easy to treat.
B. The MIC for most of the antibiotics would be low.
C. An E-test may succeed in finding antibiotic resistance, but this test has failed.
D. The bacterium probably has an R-plasmid.
E. This is an invalid test; only one disk should be used per plate.

Answer 194

The bacterium probably has an R-plasmid.

Question 195

Two antibiotics that prevent bacterial protein synthesis are . . .
A. Bacitracin and Cephalosporins
B. Rifampin and SxT
C. Chloramphenicol and Bacitracin
D. Azithromycin and Tetracycline
E. Sulfa drugs and Polymyxin B

Answer 195

Azithromycin and Tetracycline

Question 196

Most antiviral drugs target . . .
A. viral nucleic acid synthesis
B. viral protein synthesis
C. assembly of new virions
D. an unusual glycosidic bond in capsid carbohydrates
E. viral metabolism

Answer 196

viral nucleic acid synthesis

Question 197

Which of the following genes would be LEAST likely to be found on an R-plasmid?
A. Genes encoding a Type I secretion system
B. Genes encoding a beta lactamase
C. Genes encoding an ergosterol synthase
D. Genes encoding the structural proteins of a pilus
E. Genes encoding a mutant form of DNA gyrase

Answer 197

Genes encoding an ergosterol synthase

Question 198

The basic mechanism that leads to the formation of an R-plasmid is . . .
A. Horizontal Gene Transfer
B. Genetic Crossover (recombination)
C. Evolutionary Selection
D. Random Transposition
E. Spontaneous Mutation

Answer 198

Genetic Crossover (recombination)

Question 199

Cephlex is a very common prescription in the United States. What is its mode of action?
A. It disrupts cell membrane lipids.
B. It inhibits bacterial protein synthesis.
C. It interferes with viral DNA replication.
D. It competitively inhibits a metabolic enzyme.
E. It inhibits bacterial cell wall cross-linking.

Answer 199

It inhibits bacterial cell wall cross-linking.

Question 200

Which of the following antimicrobial agents would most successfully reduce the symptoms if
prescribed for a case of Herpes in a patient?
A. Polymyxin
B. Tetracycline
C. Chloroquine
D. Acyclovir
E. Amphotericin

Answer 200

Acyclovir

Question 201

Which of the following is prescribed to treat both anaerobic bacterial infections and infections
caused by flagellated protozoans such as Giardia?
A. Metronidazole
B. Sulfa drugs
C. Penicillin
D. Neuraminidase inhibitors
E. Cubicin

Answer 201

Metronidazole

Question 202

Before the antibiotic era, R-plasmids were . . .
A. nonexistent
B. present at low levels, but did not confer a selective advantage
C. even more common than they are now
D. present only in the Hfr form
E. resistant to antibodies instead of antibiotics

Answer 202

present at low levels, but did not confer a selective advantage

Question 203

The recently developed anti-MRSA drug mupirosin . . .
A. inhibits transglycosylation of peptidoglycan
B. blocks export from Type III secretory systems
C. inhibits the initiation of protein translation
D. inhibits an aminoacyl-tRNA synthetase
E. has a lower therapeutic index than previous generations of drugs in this family

Answer 203

inhibits an aminoacyl-tRNA synthetase

Question 204

Non-nucleoside polymerase inhibitors . . .
A. block replication because they lack a 3’ OH
B. could allosterically inhibit an RNA-dependent RNA polymerase
C. include drugs like amantadine
D. block viral neuraminidase as well as polymerase
E. prevent processing of viral polyproteins

Answer 204

could allosterically inhibit an RNA-dependent RNA polymerase

Question 205

A stockman notices that many of his sheep have acquired an intestinal worm infestation.
Which of the following would he most likely use to treat the infected sheep?
A. Fluconazole
B. Metronidazole
C. Ivermectin
D. Artemisinin
E. Amphotericin B

Answer 205

Ivermectin

Question 206

Which of the following is NOT involved in the inflammatory response?
A. Activation of B cells by cytokines from TH cells.
B. Adhesins, which cause phagocytes to adhere to capillary walls.
C. Secretion of IL-6, a pyrogen.
D. Dilation of capillary walls.
E. Secretion of PMNs to the tissues through capillary walls.

Answer 206

Activation of B cells by cytokines from TH cells.

Question 207

How does a phagocyte “know” not to phagocytose your own cells?
A. Your cells don’t have PMPs for the phagocyte to recognize.
B. The phagocytes that recognize self antigens are clonally deleted.
C. The phagocyte must be activated by a TC cell before it can engulf other cells.
D. The phagocytes antibodies cannot bind to your own cells.
E. The pathogen sends phagocytosis signals to the phagocyte before it is engulfed.

Answer 207

Your cells don’t have PMPs for the phagocyte to recognize.

Question 208

Why does a bacterium produce antioxidants?
A. To help your body fight off infections from other bacteria.
B. To signal phagocytes to engulf it.
C. To survive the oxidative burst inside the phagolysosome.
D. The bacterium is producing its own chemoattractants.
E. They are electron acceptors for its electron transport chain.

Answer 208

To survive the oxidative burst inside the phagolysosome.

Question 209

Which of the following is NOT a part of the innate immune system?
A. skin
B. lysozyme
C. ciliated epithelial cells
D. macrophages
E. natural killer (NK) cells

Answer 209

macrophages

Question 210

Polymorphonuclear cells (PMNs) are both . . .
A. antigen presenting cells and macrophages
B. nucleocytes and lymphocytes
C. granulocytes and phagocytes
D. macrophages and dendritic cells
E. lymphocytes and monocytes

Answer 210

granulocytes and phagocytes

Question 211

How do phagocytes recognize pathogens?
A. The pathogens are tagged first by antibodies.
B. Non-specifically, by random contact.
C. Cytokines direct the pathogens to the phagocytes.
D. Surface molecules on the pathogens are recognized by receptors on the phagocyte.
E. Mannan-binding Lectin (MBL) binds to and “tags” the pathogen’s cell membrane.

Answer 211

Surface molecules on the pathogens are recognized by receptors on the phagocyte.

Question 212

How does the lactoferrin secreted by human cells help to prevent bacterial colonization of a human
host?
A. It breaks down peptidoglycan in the bacterial cell wall.
B. It makes the skin pH too basic for bacteria to grow.
C. It makes the skin too moist for bacterial cells to adhere well.
D. It reduces iron availability, preventing bacteria from synthesizing cytochromes.
E. It doesn’t; it aids colonization by probiotic native flora.

Answer 212

It reduces iron availability, preventing bacteria from synthesizing cytochromes

Question 213

Cytokines do all of the following EXCEPT . . .
A. allow bacteria to bind specifically to phagocytes
B. recruit PMNs to the site of a bacterial infection
C. kill cancer cells
D. prevent the spread of viruses within a host
E. cause fever and inflammation

Answer 213

allow bacteria to bind specifically to phagocytes

Question 214

Which of the following is NOT a function of the innate immune system?
A. The low pH of your stomach helps you avoid foodborne infections.
B. Dendritic cells in your tissues engulf invading bacterial pathogens.
C. Infection results in inflammation and fever.
D. Antibodies produced against the flu virus make reinfection less likely.
E. Complement C3b opsonizes bacteria, allowing macrophages to recognize them better.

Answer 214

Antibodies produced against the flu virus make reinfection less likely.

Question 215

Which of the following is a phagocyte but is NOT an antigen presenting cell (APC)?
A. Polymorphonuclear Neutrophil (PMN)
B. Macrophage
C. Dendritic Cell
D. B-cell
E. Lymphocyte

Answer 215

Polymorphonuclear Neutrophil (PMN)

Question 216

A cytokine that is secreted by one type of white blood cell to stimulate the growth of another white
blood cell is a / an . . .
A. chemokine
B. interleukin
C. interferon
D. tumor necrosis factor
E. leukocidin

Answer 216

interleukin

Question 217

Which of the following is an example of a PAMP?
A. TLR12
B. CD14
C. B-lymphocyte
D. lysozyme
E. LPS

Answer 217

LPS

Question 218

Lymphocytes are different from other white blood cells (WBCs) because . . .
A. they are the only WBCs that secrete cytokines
B. they have very unusually-shaped nuclei
C. they are derived from a different stem cell lineage
D. they have many small enzyme granules in their cytoplasm
E. they can engulf bacteria and viruses by endocytosis

Answer 218

they are derived from a different stem cell lineage

Question 219

When comparing TC cells to TH cells, one difference is that . . .
A. TC cells produce antibodies
B. TH cells have MHC class II surface receptors rather than class I
C. TC cells can phagocytize bacteria
D. TH cells activate other lymphocytes; TC cells kill infected cells
E. TC cells secrete cytokines; TH cells secrete perforins

Answer 219

TH cells activate other lymphocytes; TC cells kill infected cells

Question 220

An important innate immune function of the skin is . . .
A. its cilia, which sweep away bacteria
B. its ability to produce antibodies
C. if kept clean, very few bacteria can colonize it
D. its secretion of an iron-binding protein
E. its moisture and balanced pH, which discourage bacterial attachment

Answer 220

its secretion of an iron-binding protein

Question 221

Which of the following is a leukocyte that is NOT phagocytic?
A. Polymorphonuclear Neutrophil
B. Macrophage
C. Dendritic Cell
D. Monocyte
E. Lymphocyte

Answer 221

Lymphocyte

Question 222

What is a PAMP?
A. A macrophage surface protein to which bacteria bind specifically
B. A type of cytokine responsible for T cell activation
C. A molecule on the surface of a bacterium to which phagocytes bind
D. A disease in which blood begins to clot in capillaries, leading to organ failure
E. A type of phagocyte that is specialized for engulfing viruses and prions

Answer 222

A molecule on the surface of a bacterium to which phagocytes bind

Question 223

How does opsonization help to kill bacterial cells?
A. It pokes holes in the bacterial membrane, causing the bacterium to lyse.
B. It triggers fever, which raises the body temperature just enough to kill most bacteria.
C. It prevents bacteria from colonizing body tissues.
D. It allows bacteria to be recognized and engulfed more easily by phagocytes.
E. It increases the number of PMNs during a key stage in a bacterial infection.

Answer 223

It allows bacteria to be recognized and engulfed more easily by phagocytes.

Question 224

Gram negative bacterial blood infections are often more serious than Gram positive. Why?
A. A Gram (-) PMP causes excess cytokine production, resulting in too much diapedesis.
B. Fever that gets too high allows Gram (-) bacteria to multiply very rapidly.
C. Macrophages kill host cells infected by Gram (-) bacteria; not just the bacteria.
D. Gram (-) bacteria insert a membrane attack complex into blood cells.
E. Gram (-) toxins lyse cells lining the blood vessels, allowing bacteria to spread.

Answer 224

A Gram (-) PMP causes excess cytokine production, resulting in too much diapedesis.

Question 225

Which of the following is a function of the innate immune system?
A. The acidic pH and dryness of skin make it difficult for pathogens to colonize.
B. T lymphocytes engulf invading pathogens.
C. Lactoferrin causes capillary expansion and diapedesis, bringing blood serum to the tissues.
D. Native flora covers the surface of the heart so there is no room for pathogens to attach.
E. Antibodies made against bacterial surface proteins induce the complement system.

Answer 225

The acidic pH and dryness of skin make it difficult for pathogens to colonize.

Question 226

Which of the following cytokines is correctly matched with its function?
A. Chemokines – anti-cancer therapeutic agents
B. Interferon – induces recruitment of macrophages and neutrophils to an infection site
C. Tumor necrosis factor – causes vascular permeability and inflammation
D. Interleukins – stimulate B cells to differentiate into plasma cells and produce antibodies
E. Leukocidins – stimulate fusion of lysosome and phagosome in phagocytic cells

Answer 226

Interleukins – stimulate B cells to differentiate into plasma cells and produce antibodies

Question 227

Which of the following groups of cells are all phagocytes?
A. Macrophages, Dendritic cells, and B lymphocytes
B. B lymphocytes, T lymphocytes, and NK cells
C. Neutrophils, Dendritic cells, and Macrophages
D. Granulocytes, Macrophages, and Lymphocytes
E. Myeloid cells, Lymphocytes, and Dendritic cells

Answer 227

Neutrophils, Dendritic cells, and Macrophages

Question 228

The inflammatory response . . .
A. involves mainly the adaptive immune response rather than the innate
B. causes leukocytes to adhere to, and then to leak through, blood vessel walls
C. involves constriction of capillaries to reserve blood for vital organs
D. can only occur in response to bacterial replication in the body
E. results in an large increase in blood pressure and volume

Answer 228

causes leukocytes to adhere to, and then to leak through, blood vessel walls

Question 229

Which of the following best describes the role of PMNs (“Polys”) in the immune response?
A. They produce antibodies, especially after a second exposure to an infectious organism.
B. They seek out and destroy infected “self” cells.
C. They are phagocytes that also secrete cytokines.
D. They secrete complement proteins in response to an infection.
E. Spaces between them allow leukocytes to spread from capillaries into infected tissues

Answer 229

They are phagocytes that also secrete cytokines.

Question 230

Which of the following does not describe a role the complement system plays in your body’s
response to an infection?
A. Complement proteins make invading bacteria easier to phagocytize.
B. Complement proteins induce inflammation.
C. Complement proteins enhance new capillary growth to promote wound healing.
D. Complement proteins lyse invading bacteria.
E. Complement proteins induce B cells to become plasma cells.

Answer 230

Complement proteins induce B cells to become plasma cells.

Question 231

The inflammatory response involves all of the following EXCEPT . . .
A. cytokine release
B. T lymphocyte stimulation
C. leukocyte adhesins
D. diapedesis
E. pyrogenesis (fever development)

Answer 231

T lymphocyte stimulation

Question 232

What is the role of TH cells in the adaptive immune response?
A. to phagocytize pathogens
B. to secrete perforins that kill infected cells
C. to produce antibodies
D. to secrete stimulatory interleukins
E. to secrete complement proteins that begin the complement cascade

Answer 232

to secrete stimulatory interleukins

Question 233

Which of the following correctly describes the role of skin in the innate immune response?
A. Its moisture and balanced pH make it a good environment for many bacteria to grow.
B. Its harsh conditions completely prevent colonization and growth of native flora.
C. Its ciliated epithelial cells sweep away bacteria to keep it sterile.
D. It has T-cells that phagocytize bacteria when bacteria try to penetrate the skin.
E. It secretes proteins that bind iron to reduce the amount of iron available for bacteria.

Answer 233

It secretes proteins that bind iron to reduce the amount of iron available for bacteria.

Question 234

You are a histologist working in a hospital lab. You get a tissue sample to analyze that contains
very many cells like the ones shown at the right. What can you most probably conclude?
A. The tissue came from a patient with a worm infestation.
B. The tissue came from a patient with a bacterial infection.
C. The tissue came from a patient with a chronic viral infection.
D. The tissue was taken from unbroken skin.
E. The tissue came from a lymphoid organ like the spleen

Answer 234

The tissue came from a patient with a bacterial infection.

Question 235

What is the main function of TC cells in the immune system?
A. to activate PMNs
B. to activate TH cells
C. to activate B cells
D. to initiate one of the complement pathways
E. to use perforin to kill infected cells

Answer 235

to use perforin to kill infected cells

Question 236

What do macrophages and neutrophils have in common?
A. Both are granulocytes
B. Both are phagocytes
C. Both are professional APCs
D. Both are lymphocytes
E. Both are part of the adaptive immune system

Answer 236

Both are phagocytes

Question 237

Which of the following is NOT a part of the inflammatory response?
A. Increased blood flow to the affected area
B. Diapedesis of neutrophils
C. Adhesion of phagocytes to capillary walls
D. Activation of B cells to secrete cytokines
E. Secretion of proteins that affect the hypothalamus

Answer 237

Activation of B cells to secrete cytokines

Question 238

Why are Gram negative bacterial infections more often associated with disseminated intravascular
coagulation than Gram positive bacterial infections are?
A. A component of the G(-) outer membrane binds to a protein that triggers excessive
cytokine production by macrophages.
B. Thick peptidoglycan is harder to degrade than thin peptidoglycan is.
C. G(-) cells cause the production of CD14, which kills so many macrophages that the
body has trouble overcoming the infection.
D. A component of G(-) flagella causes excess pyrogen production.
E. G(-) bacteria are more likely to grow at body temperature than G(+) are

Answer 238

A component of the G(-) outer membrane binds to a protein that triggers excessive
cytokine production by macrophages.

Question 239

Which of the following directly activate all aspects of the immune response - innate, humoral and
cellular?
A. Macrophages
B. TH cells
C. Lectins
D. Chemokines
E. PMNs

Answer 239

TH cells

Question 240

Which of the following is NOT a barrier to invasion that is typically found at a portal of entry?
A. Sticky mucus
B. A rich growth of non-pathogenic bacteria
C. Ciliated epithelial cells
D. A large concentration of PMNs
E. “Sentinel” cells that sense when the barrier is broken

Answer 240

A large concentration of PMNs

Question 241

Cytokines called interleukins are responsible for . . .
A. killing tumor cells, viruses and infected host cells
B. fever, inflammation and leukocyte maturation
C. inflammation, apoptosis and death of infected cells
D. recruiting macrophages, dendritic cells and neutrophils
E. chemotaxis of macrophages, death of viruses, and maturation of leukocytes

Answer 241

fever, inflammation and leukocyte maturation

Question 242

Viruses, such as measles, that infect this type of cell do great harm to the immune system, since
without this type of cell, humoral, cellular and innate immunity are all compromised. What type of cell
is it?
A. granulocytes
B. B cells
C. TC cells
D. TH cells
E. phagocytes

Answer 242

TH cells

Question 243

Gram negative blood infections often result in disseminated intravascular coagulation (DIC), septic
shock and death. What causes these very serious symptoms?
A. Bacterial toxins lyse cells lining the blood vessels, allowing bacteria to spread.
B. Fever that gets too high allows bacteria to multiply very rapidly.
C. Macrophages digest not only the bacterial cells, but the host’s cells, too.
D. Bacteria insert a membrane attack complex into blood cells, resulting in coagulation
E. a bacterial PMP causes excess cytokine production, resulting in too much diapedesis

Answer 243

a bacterial PMP causes excess cytokine production, resulting in too much diapedesis

Question 244

The adaptive immune system involves which of the following responses?
A. A lectin binds to bacterial surface sugars to initiate the complement cascade.
B. Phagocytes stimulate TH cells to produce cytokines.
C. Infected macrophages produce pyrogens, which can travel to the brain.
D. Dendritic cells in your tissues engulf invading bacterial pathogens.
E. The bacteria that live in your colon compete with pathogens for nutrients.

Answer 244

Phagocytes stimulate TH cells to produce cytokines.

Question 245

Complement peptide C5a is an example of . . .
A. an interleukin
B. a type of interferon
C. a chemokine
D. a granulocyte
E. an opsonin

Answer 245

a chemokine