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WorksheetsMicro test 2
Total questions: 115
Worksheet time: 58mins
In this scanning electron micrograph of Borrelia burgdorferi, which of the following structures is visible?
the outer sheath
cytoplasmic filaments
the genome
flagellar motors
The cell wall is part of the
cell membrane.
cytoplasm.
cell envelope.
proteome.
Lipopolysaccharides are found in
Gram-positive bacteria.
Gram-negative bacteria.
archaea.
eukaryotic microbes.
In Gram-negative bacteria, peptidoglycan is found in the
cytoplasm.
inner membrane.
outer membrane.
periplasm.
In this model of a Gram-negative bacterial cell envelope, which line is drawn to the periplasm?
1
2
3
4
In this model of a Gram-negative bacterial cell envelope, which line is drawn to lipopolysaccharides?
1
2
3
4
The majority of the bacterial cell cytoplasm (by total weight) is
DNA
RNA
Protein
Water
In an E. coli cell, which molecule is found in only 1–2 copies per cell?
DNA
RNA
Protein
Phospholipids
Which bacterial cellular constituent is most liable to change under changing environmental conditions?
DNA
Peptidogylcan
Polyamines
Proteins
The cell membrane stores energy by maintaining a separation of
DNA
Proteins
Ions
Lipids
In Gram-negative bacteria the cell membrane separates the
periplasm from the external environment.
cytoplasm from the external environment.
cytoplasm from the nucleoid.
DNA from the RNA.
In the image shown the circles and squares indicate molecules. The circles are at a higher concentration outside the cell and the squares are at a higher concentration inside the cell. Which of the following statements is correct?
Energy is released if the circles move into the cell or if the squares move out of the cell.
Energy is released if the circles move into the cell or if the squares move into the cell.
Energy is released if the circles move out of the cell or if the squares move out of the cell.
Energy is released if the circles move out of the cell or if the squares move into the cell.
In this image the energy released by the transport of the circles out of the cell is used to drive the import of the squares into the cell. This is an example of
passive transport.
facilitated diffusion.
symport coupled transport
antiport coupled transport.
In this image a transmembrane protein moves circles out of the cell, providing energy to move squares into the cell. Which of the following is correct?
Both the circles and the squares move down their concentration gradients.
Both the circles and the squares move against their concentration gradients.
The circles move down their concentration gradient and the squares move against their
The circles move against their concentration gradient and the squares move down their
concentration gradient.
What is the cellular target of penicillin (the first antibiotic discovered)?
genome
the cell wall
ribosomes
ABC transporters
How does the cell wall protect bacterial cells from osmotic shock?
The wall forms a rigid cage that withstands turgor pressure.
The wall is impermeable to water, preventing turgor pressure.
The wall is impermeable to ions and other solutes, preventing osmotic imbalance.
The wall ensures cells are only found in environments where turgor pressure will not
occur.
The bacterial cell wall is an attractive target for antibiotics because
bacterial cells cannot develop resistance to antibiotics that target the cell wall.
animal cells lack a cell wall.
the cell wall is unimportant for bacterial survival.
the cell wall is the only structure bacteria require for survival.
Mycoplasma lost their cell walls via reductive evolution. This was possible because
their cell membranes became extra thick to compensate.
it allowed them to not be sensitive to antibiotics that target the cell wall.
as obligate parasites they live in environments with constant osmolarity.
they live in soils with plenty of available moisture.
This image models a
Gram-positive cell envelope.
Gram-negative cell envelope.
eukaryotic cell membrane.
mycobacterial envelope.
Which of the following is FALSE of teichoic acids?
They reinforce the cell wall.
They may help pathogens attach to host cells
They are recognized by the host immune system.
They repel the Gram stain.
This transmission electron micrograph shows a
Gram-positive cell envelope.
Gram-negative cell envelope.
eukaryotic cell membrane.
mycobacterial envelope.
Murein lipoprotein is a part of the ________ of the ________.
outer leaflet, outer membrane.
inner leaflet, outer membrane.
outer leaflet, inner membrane.
inner leaflet, inner membrane.
Which of the following is a function of lipopolysaccharide?
helps cells resist phagocytosis
aids in outer membrane cell wall attachment
allows for mobility to promote chemotaxis
provides energy to the cell
Which of the following helps compact bacterial DNA?
the origin of replication site
supercoils
porins
pilins
Which of the following is true of growing bacteria?
DNA synthesis occurs continuously.
DNA synthesis occurs during a defined period.
They suspend flagella rotation to put energy toward DNA replication.
DNA synthesis cannot occur at the same time as transcription.
The arrows indicate the partition that separates a bacterial cell into two new daughter cells. This partition is called the
stalk
S-layer.
septum
termination site
Bacterial cells that expand their cell walls during septation (not before) and septate in parallel planes will form
chains of rods (bacilli).
tetrads of rods (bacilli)
chains of spheres (cocci)
tetrads of spheres (cocci)
This electron micrograph shows staphylococci, spherical cells that cluster together like grape bunches. This form occurs when cell wall expansion occurs
prior to septation and septation occurs in parallel planes.
prior to septation and septation occurs in random orientations.
during septation and septation occurs in parallel planes
during septation and septation occurs in random orientations.
Which of the following structures is obligatory for all bacterial cells?
nucleoid
flagella
pili
magnetosomes
Pili and stalks enable bacterial
adherence
chemotaxis
photosynthesis
symport
While most wild E. coli usually have flagella, many lab strains have lost their flagella. What is a likely
cause of this loss?
reductive evolution due to an increased need for chemotaxis
reductive evolution due to an unchanging environment
reductive evolution due to an increased need for magnetotaxis
reductive evolution due to a decreased need for magnetotaxis
Flagella are required for bacterial
chemotaxis
growth
adherence
buoyancy
This transmission electron micrograph of a marine microbe shows internal structures such as thylakoids. This microbe has what capability that is not present in all bacterial species?
adherence
chemotaxis
DNA replication
photosynthesis
Magnetotactic bacteria swim along a magnetic field. To do this these bacteria have which of the following structures that are not present in all bacterial species?
storage granules
sulfur
flagella
gas vesicles
Which organelle is NOT part of the endomembrane system?
mitochondrion
lysosome
peroxisome
Golgi complex
Ribosomes associate with which endomembrane organelle?
Golgi complex
endoplasmic reticulum
lysosomes
peroxisomes
Which of the following shows the correct path a secreted protein takes in a eukaryotic cell?
Golgi complex, rough ER, vesicle, cell membrane
vesicle, rough ER, Golgi complex, cell membrane
rough ER, Golgi complex, vesicle, cell membrane
rough ER, Golgi complex, cell membrane, vesicle
Which organelle houses a eukaryotic cell’s genome?
rough endoplasmic reticulum
contractile vacuole
ribosome
nucleus
Which organelle arose via endosymbiosis?
chloroplast
Golgi apparatus
lysosome
nucleus
ATP synthase is found in bacterial cell membranes. In eukaryotic cells, ATP synthase is found in the
cell membrane.
cytoplasm.
mitochondrial inner membrane.
mitochondrial matrix.
Mycobacterium leprae, or leprosy disease, often takes years to develop. Naranjan must use a long-term multidrug therapy to cure it. Why is it necessary to take the drugs for such a long period, and why must he take so many drugs at once?
Mycobacteria are Gram-negative organisms. They must be killed slowly to prevent release of toxic LPS
Mycolic acid within the cell wall reduces nutrient uptake, resulting in slow growth, and excludes some antibiotics.
Mycobacteria are all highly resistant to antibiotics.
Mycobacteria don’t have cell walls, so must be treated with antibiotics that target other
structures.
Given the incredibly fast division times of bacterial cells, which of the following could explain why
we are NOT surrounded by large mountains of bacterial cells?
Bacteria produce too much toxic iron.
Bacteria require a host cell to grow.
Bacteria are outcompeted by viruses.
Bacteria run out of nitrogen.
Which of the following is needed as an important enzyme cofactor for microbial growth?
Na+
Mg2+
sulfur
oxygen
Examine the media recipes shown. What ingredients make Luria Bertani a complex medium as opposed to a chemically defined minimal medium?
tryptone and NaCl
tryptone and yeast extract
NaCl and yeast extract
Luria Bertani is a chemically defined minimal medium.
Which of the following could describe the relationship between the cyanobacterium Nostoc and E. coli
related to the carbon cycle?
Nostoc produces carbohydrates from lithotrophy, and E. coli breaks down the
carbohydrates to generate CO2.
Nostoc produces carbohydrates from phototrophy, and E. coli breaks down the
carbohydrates to generate CO2.
Nostoc produces CO2 that E. coli turns into carbohydrates.
E. coli produces carbohydrates that Nostoc uses as energy to produce more carbohydrates.
Which of the following statements regarding examples of chemotrophy is FALSE?
Glucose is an oxidized compound that freely donates electrons to NAD, a more reduced
compound.
Glucose is a reduced compound that freely donates electrons to NAD, a more oxidized
compound.
NAD plays an important role in chemotrophic metabolism.
Glucose is an important chemotrophic carbon source.
What is the correct term for the chemical conversion shown below?
phototrophy
nitrification
denitrification
nitrogen fixation
What advantage does the plating method shown on the left panel below have over the plating method
shown in
the right panel?
It can be used to isolate pure colonies.
It can be used to culture viable organisms.
It can be used to produce confluent growth
It can be used to quantify the number of organisms in a given bacterial sample
Fastidious organisms would be best grown on which type of media?
enriched
synthetic
minimal
selective
Mannitol salts agar is a medium that contains a high concentration of salt (7.5%) and mannitol as a fermentable carbon source. Few organisms are able to grow on it because of its high salt concentration. Organisms that can grow and ferment mannitol will produce an acid that interacts with the pH indicator in the media, turning it yellow. Nonmannitol-fermenting organisms grow without any change to the media. Which of the following correctly describes this medium?
selective
differential
selective and differential
neither
Which of the following can be used to directly count bacterial cells without the use of a microscope?
viable counts
optical density
fluorescence-activated cell sorter
Petroff-Hauser counting chamber
Which of the following is NOT a problem with the viable count method of cell quantification?
underestimation of the number of living cells in the culture
takes too long if you want to immediately study cells at a particular growth phase
not accurate for organisms whose cells remain attached (for example, Streptococci
growing in chains)
not useful for living cells
Which of the following can be most efficiently used to measure bacterial growth in real time?
FACS
spectrophotometer
Petroff-Hauser counting chamber
fluorescent microscope
Which of the following is NOT required for microorganisms to grow and divide?
DNA replication
binary fission
equatorial septum formation
conjugation
A culture of Salmonella increases from 20 cells to over 10,000 cells in just three hours. Of what is this an example?
lag phase
doubling time
budding
exponential growth
If you start with 14 organisms at time 0, how many organisms will you have after 9 generations, assuming exponential growth?
126
512
7,168
14,336
Which of the following is NOT happening during the lag phase of growth?
Cells are at their largest.
Genes for growth in the specific environment are turned on.
Cell components are being synthesized.
Cells are detecting their environment.
Bacteria begin to participate in quorum sensing at which stage of growth?
late log phase
log phase
stationary phase
stationary
A new enzyme that helps protect a bacterial cell from reactive oxygen species has been discovered. During which phase of growth would you expect the gene that codes for this enzyme to be expressed?
lag phase
log phase
late log phase
stationary phase
Which of the following occurs when a microorganism is found in an environment below its minimum
growth temperature?
The cell dies.
Growth stops because the cell membrane melts.
Growth stops because enzymatic processes become sluggish.
Growth slows but does not stop.
What classification is also given to barophilic organisms that grow at the ocean floor?
mesophilic
psychrophilic
halophilic
acidophilic
Which of the following is true regarding an environment with a high osmolarity?
It has a low salt concentration.
It has a high pH.
It has a high water activity.
It has a low water activity.
Which of the following cellular components could be found in high concentrations in a halophilic microorganism?
Na+/K+ ion pump
citric acid
cold-tolerant enzymes
asuperoxide dismutase
Production of urease by Helicobacter pylori allows it to do which of the following?
sense when it has entered the intracellular environment of its host
survive in basic conditions
increase production of ion pumps
neutralize stomach pH to survive in acidic conditions
Which of the following is NOT a toxic by-product of oxygen metabolism?
superoxide
hydroxide radicals
hydrogen peroxide
dihydrogen oxide
Consider the tube shown. What type of organism would grow only at the bottom of the tube?
microaerophile
aerotolerant anaerobe
strict anaerobe
strict aerobe
Why do strict anaerobes die in the presence of oxygen?
They are vulnerable to reactive oxygen species.
They are not able to get enough energy without using oxygen as a terminal electron
acceptor.
They do not use oxygen as a terminal electron acceptor
Strict anaerobes do not die in the presence of oxygen.
Why might a facultative organism prefer aerobic respiration over fermentation when carbohydrates
become scarce?
Facultative organisms never prefer aerobic respiration to fermentation.
It gets more energy from fermentation.
It gets more energy from aerobic respiration.
It gets less energy from aerobic respiration.
What is the purpose of the palladium packet in the anaerobic jar?
to catalyze a reaction between H2 and residual O2 in the jar to remove all the O2
to remove CO2 that can be converted to O2
to provide O2 for aerobic respiration
to provide N2 for protein synthesis
Which of the following is NOT an example of a bacterial organism that can form a biofilm?
All bacterial organisms can form biofilms.
Pseudomonas aeruginosa
Escherichia coli
Bacillus anthracis
Why do bacterial organisms form a biofilm?
to claim territory and fight off competing organisms of a different species
to attach to a surface in an area where food is plentiful
to find a food source when nutrients are scarce
to mate with other bacterial organisms of the same or different species
Which of the following is NOT involved in biofilm formation or function?
rorespore engulfment
quorum sensing
exopolysaccharide formation
antibiotic resistance
Which of the following is NOT necessary for endospore formation?
exopolysaccharide formation
peptidoglycan synthesis
dipicolinic acid synthesis
calcium transport
If an error occurred during the sporulation process and small acid-soluble proteins were not included in
the spore, what would be the effect?
The spore would only exist for 100 years.
The spore will be more likely to germinate.
The spore will be less resistant to heat.
The spore will be less resistant to ultraviolet light.
The blood agar plates used to culture Mirembe’s sample contain intact red blood cells and agar. Organisms that are capable of lysing the red blood cells may produce green-appearing zones of partial hemolysis or clear-appearing zones of complete hemolysis around colonies that are easily visually distinguishable. This medium is best described as:
selective
differential
chemically defined
synthetic
Which of the following is found in eukaryotic but not prokaryotic genomes?
promoters
operons
introns
genes
Each bacterial species has a unique
cell shape
cel wall
genome
glycolytic pathway
Which of the following is true of plasmids?
They can be the entire genome.
They are common in eukaryotic cells.
They are usually linear
They may contain antibiotic resistance genes.
Plasmids usually contain genes that are
important for cell survival in all environments.
important for cell survival in particular environments.
not important for cell survival in any environments.
composed of single-stranded DNA.
In this image of a nucleoside, which arrow is pointing to the 2¢ carbon of deoxyribose?
1
2
3
4
In this image of a nucleoside, which arrow is pointing to the 5¢ carbon of deoxyribose?
1
2
3
4
In the active site of DNA polymerase, which monomer will form correct base pairs with a C in the
template strand?
dATP
dCTP
dGTP
dTTP
An E. coli cell whose DNA contains N14 is placed in media with dNTPs containing a heavy isotope of nitrogen, N15, which incorporates into newly synthesized DNA. After one cell division, what will the DNA in the daughter cells look like?
One cell will have both strands of the helix N14; the other cell will have both strands of the helix N15.
One cell will have mostly N14 with a little bit of N15; the other cell will have mostly N15 with a little N14.
Each cell will have one strand of N14 and one strand of N15.
It is impossible to predict what the DNA in the daughter cells will look like.
If you wanted to radioactively tag newly synthesized DNA, which numbered phosphate would need to be radioactive?
1
2
3
Either 1, 2, or 3 would work.
DNA replication begins at a chromosomal region called the
activator
initiator
origin
promoter
The activity of what enzyme is modeled here?
gyrase
helicase
DNA polymerase
primase
Which of the following lists enzymes involved in DNA replication in the order they act?
primase, helicase, DNA polymerase
helicase, DNA polymerase, primase
primase, DNA polymerase, helicase
helicase, primase, DNA polymerase
TAT is a codon for the amino acid tyrosine (Tyr). If a mutation changes TAT to TAA, what kind of mutation has occurred?
frameshift
missense
nonsense
silent
TAT is a codon for the amino acid tyrosine (Tyr). If a mutation changes TAT to CAT, what kind of mutation has occurred?
frameshift
missense
nonsense
silent
A mutation known as a pyrimidine dimer is usually caused by
acridine orange
DNA polymerase errors.
UV light
X-rays
Which repair process leads to an abasic site as part of the repair pathway?
base excision repair
methyl mismatch repair
recombination
SOS repair
During gel electrophoresis the ________ DNA fragments migrate more quickly and move further
down the gel toward the ________ pole.
larger; negative
larger; positive
smaller; negative
smaller; positive
RFLP analysis requires which tools?
restriction enzymes and gel electrophoresis
restriction enzymes and PCR
gel electrophoresis and PCR
gel electrophoresis and DNA sequencing
Recombinant human insulin is safely produced in bacteria. Which of the following is the correct
sequence of steps needed to produce such a transgenic bacterium?
transform bacteria, ligate, hybridize insulin cDNA and plasmid
hybridize insulin cDNA and plasmid, ligate, transform bacteria
hybridize insulin cDNA and plasmid, transform bacteria, ligate
ligate, hybridize insulin cDNA and plasmid, transform bacteria
What technique is illustrated in this diagram?
DNA hybridization
DNA sequencing
recombinant DNA production
PCR
Which of the following RNAs gets translated into protein?
mRNA
rRNA
tRNA
sRNA
If a portion of the template strand of a gene has the sequence 5¢ TTGCAGCT 3¢, what is the sequence of the RNA transcribed from this template?
5¢AACGTCGA3¢
5¢AACGUCGA3¢
5¢ AGCUGCAA3¢
5¢ AGCTGCAA3¢
During transcription termination
sigma disengages from RNA polymerase.
RNA polymerase disengages from the DNA.
ribosomes disengage from the mRNA.
DNA replicates the termination sequence.
What enzyme is used to produce cDNA?
DNA polymerase III
DNA ligase
RNA polymerase
reverse transcriptase
Which of the following is NOT normally found in human cells?
cDNA
DNA
mRNA
tRNA
Which of the following is most likely a signature of an operon?
large distances between consecutive coding regions and functional association of the gene products
large distances between consecutive coding regions and gene products involved in different pathways
short distances between consecutive coding regions and gene products involved in different pathways
l
short distances between consecutive coding regions and functional association of gene products
Ribosomes are composed of
protein only
RNA only
both protein and rRNA
both protein and tRNA
What energy source is used to drive translation?
ATP
GTP
NADPH
the energy released when peptide bonds form
An antibiotic that inhibits peptidyl transferase activity likely binds to
aminoacyl-tRNA synthetase.
mRNA
a 30S ribosome subunit.
a 50S ribosome subunit.
Except for the initiating fMet tRNA, what is the order of sites that tRNAs take through a ribosome?
first E, then P, and finally A
irst A, then P, and finally E
first E, then A, and finally P
first P, then A, and finally E
EF-G is involved in
transcription initiation.
transcription elongation.
translation initiation.
translation elongation.
After translation
all proteins are folded and secreted.
some proteins are folded but all are secreted.
all proteins are folded and some are also secreted.
some proteins are folded and another subset are secreted.
Phase variation controls protein levels by
altering the DNA sequence.
changing the rate of mRNA translation.
changing the rate of mRNA stability.
changing the rate of protein stability.
Bacteria regulate virulence gene expression because
he genes need to be expressed all the time.
the genes do not need to be expressed all the time, and regulation saves energy.
the genes do not need to be expressed all the time; if they were, the bacterial cell would
die.
it does not cost them any energy to keep the gene expressed all the time.
The gene that codes for a protein involved in detoxifying an environmental toxin is only expressed in the presence of the toxin. A repressor protein controls transcription of the gene. Which of the following is true?
The toxin mediates induction of the gene by relieving repression imposed by the repressor.
The toxin mediates induction of the gene by stimulating activation mediated by an
activator.
The toxin mediates repression of the gene by relieving repression imposed by the
repressor.
The toxin mediates repression of the gene by stimulating activation mediated by an
activator.
PrfA protein is a global regulator of virulence genes in Listeria, a bacterium that can cause severe food poisoning. Below host body temperatures PrfA mRNA exists in a conformation that hides the ribosome binding site. Upon entry into a host and a rise in temperature, hydrogen bonds in the mRNA break, exposing the ribosome binding site. What level of gene regulation is seen here?
changing the DNA sequence
transcription control
translation control
posttranslational control
In a typical two-component signal transduction system
the sensor kinase senses the environment and the response regulator directly alters transcription.
both the sensor kinase and the response regulator sense the environment.
both the sensor kinase and the response regulator directly alter transcription.
the sensor kinase directly alters transcription and the response regulator senses the
environment.
In the lac operon, a mutation in the operator, LacO, that prevents repressor binding will cause which of the following changes compared to wild type cells?
more expression of the lac operon when lactose is present
more expression of the lac operon when lactose is absent
less expression of the lac operon when lactose is present
less expression of the lac operon when lactose is absent
In a two-component signal transduction system the response regulator activity is altered via phosphorylation. This is an example of
changing the DNA sequence.
transcription
translation control
posttranslational control.
Doxycycline is an antibiotic that binds to the bacterial ribosome. How does this antibiotic interfere
with the creating of proteins in bacterial cells?
Binding to the ribosome prevents DNA strands from being separated properly, preventing
transcription.
Binding to the ribosome prevents mRNA strands from being properly assembled from
single-stranded DNA templates.
Binding to the ribosome prevents mRNA from being properly read and translated into an
amino acid sequence.
Binding to the ribosome prevents completed proteins from being exported to the cell
surface.
