Microbiology 2
Strictly fermentative organisms have ATPases which are used to generate a proton gradient. True False
True
One alternative to autoclaving for sterilization of liquids is filtration. Imagine that you are using a filter to sterilize a drug solution. You use a filter with a 0.22 micron pore size. Which of the following microbes will effectively be removed by this filter? Select all that apply. a. yeast b. small viruses c. bacteria such as E. coli d. fungi
a. yeast c. bacteria such as E. coli d. fungi
From a plate count experiment in which you spread 0.1 ml onto each of two different agar plates from a 1:100,000 dilution of a culture, you count 150 colonies on one plate and 122 colonies on a duplicate plate. How many bacteria/ml were there in the original sample? a. 1.36 × 10^8 bacteria/ml b. 1.36 × 10^6 bacteria/ml c. 1.36 × 10^5 bacteria/ml d. 136 bacteria/ml
a. 1.36 × 10^8 bacteria/ml
Which statement is FALSE? a. Amino acids are the most frequently required microbial growth factors. b. Sugars transported via the phosphotransferase system always travel down their concentration gradient. c. E. coli can synthesize all its needed organic molecules from glucose. d. Streptococci require more growth factors than E. coli. e. Iron is typically required in larger amounts than other trace elements.
a. Amino acids are the most frequently required microbial growth factors.
Under which of the following conditions is a long lag phase LEAST likely to occur? a. An exponentially growing culture is transferred into the same medium under the same growth conditions. b. An inoculum of damaged cells is transferred into the same medium. c. A microbial population is transferred from a rich culture medium to a poor one. d. An inoculum is taken from a stationary-phase culture and transferred into the same medium. e. An innoculum of endospores is transferred to the medium.
a. An exponentially growing culture is transferred into the same medium under the same growth conditions.
Researchers suggested that Archaeal flagella be renamed as archaella because a. Archaea have no homologues to Bacterial genes involved in flagellum structure and assembly. b. Archaeal flagella are similar to Bacterial sex pili. c. they are more similar to eukaryotic flagella. d. All the choices are correct. e. Archaeal flagella are driven by proton motive force.
a. Archaea have no homologues to Bacterial genes involved in flagellum structure and assembly.
Given the following reduction potentials for various redox half reactions, in a lithotroph capable of utilizing Fe2+ as an energy source, which substances would be potential terminal electron acceptors for respiration? Fe3+/Fe2+ +0.20V NO2-/NH3 +0.34V O2/H2O +0.82V a. Both O2 and NO2- are possible electron acceptors b. Both NH3 and H2O are possible electron acceptors c. NO2- d. NH3 e. O2
a. Both O2 and NO2- are possible electron acceptors
What makes penicillin and other β-lactam antibiotics effective antibiotics? a. Cells are generally hypertonic relative to their environment, so they burst when a cell wall is damaged. b. Cells are generally hypertonic relative to their environment, so they desiccate when a cell wall is damaged. c. Cells may burst or desiccate when a cell wall is damaged. d. Cells are generally hypotonic relative to their environment, so they burst when a cell wall is damaged.
a. Cells are generally hypertonic relative to their environment, so they burst when a cell wall is damaged.
During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants are true? Select all that apply a. Disinfection can occur by physical or chemical means. b. Disinfectants destroy all microbes present on a surface. c. Disinfectants are used to inhibit or destroy pathogens. d. Disinfection can be used to treat work surfaces as well as workers (i.e., washing hands). e. Endospores and viruses can resist disinfectant treatment.
a. Disinfection can occur by physical or chemical means. c. Disinfectants are used to inhibit or destroy pathogens. e. Endospores and viruses can resist disinfectant treatment.
Microbes have undergone a number of adaptations to survive in the cold. Which of the following statements is FALSE? a. Enzyme flexibility is maintained by increasing the number of hydrogen and ionic bonds. b. Enzyme catalytic functionality arises through more alpha-helical secondary structures. c. Membrane damage can be prevented by the production of molecules such as glycerol. d. Membrane fluidity is maintained by a higher percentage of unsaturated fatty acids.
a. Enzyme flexibility is maintained by increasing the number of hydrogen and ionic bonds.
Which of these statements regarding temperature limits to growth are TRUE? Select all that apply. a. In general, eukaryotic microorganisms can grow at higher temperatures than plants and animals. b. Among eukaryotic microbes, algae can grow at the highest temperatures. c. In general, prokaryotic organisms can grow at higher temperatures than eukaryotic organisms. d. The most thermophilic prokaryotes are species of Archaea. e. Nonphototrophic organisms are able to grow at higher temperatures than phototrophic organisms.
a. In general, eukaryotic microorganisms can grow at higher temperatures than plants and animals. c. In general, prokaryotic organisms can grow at higher temperatures than eukaryotic organisms. d. The most thermophilic prokaryotes are species of Archaea. e. Nonphototrophic organisms are able to grow at higher temperatures than phototrophic organisms.
A microbe growing in a refrigerator is likely a. Psychrotolerant or psychrophilic b. Psychrotolerant c. Thermophilic d. Mesophilic e. Psychrophilic
a. Psychrotolerant or psychrophilic
The site of septum formation in E. coli is determined by the MinCDE proteins. Which of the following statements regarding the positioning of the septum are correct? a. The concentration of MinCDE proteins is lowest in the midpoint of the cell. b. MinCDE proteins are fixed at the site of septum formation. c. MinCDE proteins form the scaffold for septum construction. d. The concentration of MinCDE proteins is highest in the midpoint of the cell.
a. The concentration of MinCDE proteins is lowest in the midpoint of the cell.
Which of the following is/are true regarding reverse electron transport? Select all that apply. a. The endergonic reduction of NAD(P) is driven by the proton motive force. b. Reverse electron transport is required to reduce NAD (E0' = -0.32V) when H2S (E0' = -0.28V) is used as an electron donor. c. Reverse electron transport is unnecessary in chemorganotrophs. d. Electrons move in a reverse direction through an electron transport chain toward increasingly more positive reduction potentials. e. ETC Complex I runs in reverse and transfers electrons to NAD(P).
a. The endergonic reduction of NAD(P) is driven by the proton motive force. b. Reverse electron transport is required to reduce NAD (E0' = -0.32V) when H2S (E0' = -0.28V) is used as an electron donor. c. Reverse electron transport is unnecessary in chemorganotrophs. e. ETC Complex I runs in reverse and transfers electrons to NAD(P).
How does the proton motive force lead to production of ATP? a. Translocation of three to four protons drives the F0 component of ATPase, which in turn phosphorylates one ADP into ATP. b. ATPase requires one proton to make one ATP. c. Oxidative phosphorylation of ADP by ATP synthase requires protons as cofactors in the reaction. d. Protons must be pumped against a concentration gradient from outside of the cell into the cell to rotate the F0 subunit of ATPase for the F1 subunit to make ATP.
a. Translocation of three to four protons drives the F0 component of ATPase, which in turn phosphorylates one ADP into ATP.
Which of the following could find a location in or on human body tissues suitable for growth? Select all that apply a. anaerobes b. psychrophiles c. facultative anaerobes d. mesophiles e. halotolerant bacteria
a. anaerobes c. facultative anaerobes d. mesophiles e. halotolerant bacteria
Fts proteins are essential for bacterial cell division because they __________. Select all that apply. a. are involved in the pulling apart the two copies of the chromosome b. are involved in copying the DNA c. are involved in forming the divisome d. are involved in peptidoglycan synthesis
a. are involved in the pulling apart the two copies of the chromosome c. are involved in forming the divisome d. are involved in peptidoglycan synthesis
To speed up the growth rate in a chemostat, the ___ should be increased. To increase the cell yield as well, _____ should be increased. a. dilution rate / limiting nutrient b. limiting nutrient / dilution rate c. limiting nutrient / limiting nutrient d. dilution rate / dilution rate
a. dilution rate / limiting nutrient
The optimal growth temperature of a bacterium is most closely related to the optimal temperature for a. enzyme function. b. mRNA attachment to ribosomes. c. DNA replication. d. membrane stability e. transcription of DNA.
a. enzyme function.
When water activity is low, an organism must a. increase its internal solute concentration. b. decrease its internal solute concentration. c. increase its external solute concentration. d. decrease its external solute concentration.
a. increase its internal solute concentration.
What is a key difference between substrate level phosphorylation and oxidative phosphorylation? a. oxidative phosphorylation requires ATP synthase b. oxidative phosphorylation occurs in anaerobic organisms c. substrate level phosphorylation requires oxygen d. oxidative phosphorylation occurs when enough energy is released for phosphorylation of ADP e. all the above are key differences between substrate level phosphorylation and oxidative phosphorylation
a. oxidative phosphorylation requires ATP synthase
Both lysozyme and penicillin disrupt the bacterial cell wall peptidoglycan, leading to cell lysis. However, their mechanisms of action are different, based on the fact that __________. a. penicillin kills only growing cells b. lysozyme cleaves the peptide cross-links in peptidoglycan. c. penicillin cleaves the glycosidic bonds in the peptidoglycan d. penicillin kills both bacterial and eukaryotic cells e. penicillin cleaves the peptide cross-links in peptidoglycan.
a. penicillin kills only growing cells
The order Lactobacillales within Firmicutes are also called the lactic acid bacteria, because these bacteria a. produce lactate. b. can aerobically catabolize lactic acid. c. can ferment lactate. d. uniquely require lactic acid as a precursor for cell wall biosynthesis.
a. produce lactate.
Which feature of anaerobic and aerobic respiration is different between the two catabolic strategies? a. terminal electron acceptor b. use of electron transport c. electron donor d. use of proton motive force e. electron donor and terminal electron acceptor
a. terminal electron acceptor
The prokaryotic transport system that involves a substrate-binding protein, a membrane-integrated transporter, and an ATP-hydrolyzing protein is a. the ABC transport system. b. simple transport. c. symport. d. group translocation.
a. the ABC transport system.
Fluorescent in situ hybridization (FISH) can be used to determine: (select all that apply) a. the phylogenetic diversity of an environmental sample b. how many Salmonella typhimirium cells are present in a sample of unpasteurized apple juice c. genes of interest in the genomes of individual microbial cells d. spatial organization of community partners
a. the phylogenetic diversity of an environmental sample b. how many Salmonella typhimirium cells are present in a sample of unpasteurized apple juice c. genes of interest in the genomes of individual microbial cells d. spatial organization of community partners
Transport proteins (transporters) require energy expenditure for each molecule of substrate transported. The reason for this energy requirement is __________. a. the solute must be transported against a concentration gradient b. the solute must be chemically altered c. the solute must be forced through the hydrophobic membrane d. the conformational shape of the solute must be changed during transport
a. the solute must be transported against a concentration gradient
Superoxide dismutase and catalase work together to convert superoxide into a. water and oxygen. b. peroxide. c. oxygen. d. water.
a. water and oxygen.
Identifying carboxysomes in a bacterium suggests it a. will use the Calvin cycle to convert the concentrated CO2 into biomass. b. contains the reverse citric acid cycle. c. has a deficient Calvin cycle and accumulated CO2. d. is in a carboxylic acid rich environment and is storing excess quantities for potentially harsh conditions.
a. will use the Calvin cycle to convert the concentrated CO2 into biomass.
A cell culture in exponential growth contained 10^6 cells/ml at 1 pm, and at 4 pm the cell density was 1.6 × 10^7 cells/ml (log10 = 7.204). How many generations did this amount of growth represent? a. 2 b. 4 c. 1 d. 16 e. 8
b. 4
The energy required for nutrient transport is supplied by a. ATP. b. ATP, the proton motive force, or phosphoenol pyruvate. c. the proton motive force. d. phosphoenol pyruvate.
b. ATP, the proton motive force, or phosphoenol pyruvate.
Which statement is FALSE? a. The most extreme extremophiles typically are Archaea. b. An organism's optimal pH for growth refers to the pH of its intracellular environment. c. Some alkaliphiles utilize a sodium motive force instead of a proton motive force. d. Enzymes from thermophiles and hyperthermophiles are more resistant than their mesophilic counterparts to denaturing agents such as organic solvents and pH extremes. e. None of the statements are false.
b. An organism's optimal pH for growth refers to the pH of its intracellular environment.
What will happen to a cyanobacterium that has its photosystem II (PSII) blocked? a. Additional electron acceptors, such as NADP+, will be required to oxidize oxygen and overcome the lost PSII process. b. Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H2S. c. Photons will generate excessive reactive oxygen species and the cyanobacterium will die as a consequence. d. It will die from being unable to obtain energy for photosynthesis.
b. Anoxygenic photosynthesis only using photosystem I (PSI) could occur by using cyclic photophosphorylation and an alternative electron donor such as H2S.
Different arrangements and structures of flagella contribute to changes in speed and direction when necessary. Which of the following correctly relates motility to flagellation? a. Peritrichously arranged flagella may only rotate counterclockwise. b. Bacteria with peritrichously arranged flagella change direction by changing the flagellar rotation and "tumbling." c. Certain flagellated prokaryotes exhibit gliding motility, a slower and smoother form of movement along the long axis of a cell. d. Bacteria with lophotrichously arranged flagella change direction only by changing the flagellar rotation.
b. Bacteria with peritrichously arranged flagella change direction by changing the flagellar rotation and "tumbling."
Alternative autotrophic routes to the Calvin cycle such as the reverse citric acid cycle and the hydroxypropionate pathway are unified in their requirement for a. NAD(P)H. b. CO2. c. organic compound(s) formed. d. coenzyme A.
b. CO2.
The class of macromolecules in microorganisms that contributes LEAST to biomass is a. carbohydrates b. DNA c. proteins d. RNA e. lipids
b. DNA
Which statement is FALSE? a. Respiration by both chemolithotrophs and chemoorganotrophs depends on oxidative phosphorylation for energy conservation. b. Most chemolithotrophs are heterotrophic. c. In chemolithotrophic metabolism, electrons from the oxidation of an inorganic electron donor directly enter an electron transport chain. d. Chemolithotrophs use aerobic or anaerobic respiration. e. Most chemolithotrophs use reverse electron transport to generate reducing power.
b. Most chemolithotrophs are heterotrophic.
The major shape-determining factor in Bacteria is the protein a. MinD. b. MreB. c. crescentin. d. FtsZ.
b. MreB.
Which of the following is/are true regarding reverse electron transport? Select all that apply. a. Electrons move in a reverse direction through an electron transport chain toward increasingly more positive reduction potentials. b. Reverse electron transport is unnecessary in chemorganotrophs. c. The endergonic reduction of NAD(P) is driven by the proton motive force. d. Reverse electron transport is required to reduce NAD (E0' = -0.32V) when H2S (E0' = -0.28V) is used as an electron donor. e. ETC Complex I runs in reverse and transfers electrons to NAD(P).
b. Reverse electron transport is unnecessary in chemorganotrophs. c. The endergonic reduction of NAD(P) is driven by the proton motive force. d. Reverse electron transport is required to reduce NAD (E0' = -0.32V) when H2S (E0' = -0.28V) is used as an electron donor. e. ETC Complex I runs in reverse and transfers electrons to NAD(P).
Predict the effect of greatly reduced levels of FtsZ proteins in growing E. coli cells. a. The cells will divide uncontrollably, leading to very small, almost coccoid cells. b. The cells will continue to elongate but will be unable to form a septum and divide, leading to very elongated cells. c. The FtsZ ring will form at the center of the cell but will be unable to depolymerize, leading to cells that form septa but are permanently attached and form long chains. d. The cells would stop growing and soon die.
b. The cells will continue to elongate but will be unable to form a septum and divide, leading to very elongated cells.
The preferred method of sterilization during drug production is heat. Heat sterilization can occur in two forms: moist or dry. Autoclaving is the most commonly used application of moist heat for sterilization. Which of the following statements about autoclaving is true? a. When autoclaving solid items, they should be wrapped in foil to help maintain sterility. b. The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature. c. Autoclaving requires extensive exposure times in order to achieve sterilization. d. Autoclaving is preferred over dry heat because it can effectively be used to sterilize a wide variety of items, including liquids, powders, metal instruments, and glassware.
b. The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature.
Which statement below demonstrates why the majority of organisms are heterotrophs? a. The majority of organisms conserve energy from inorganic sources. b. The majority of organisms obtain their carbon from organic sources. c. The majority of organisms obtain their carbon from inorganic sources. d. The majority of organisms conserve energy from inorganic sources and their carbon from organic sources.
b. The majority of organisms obtain their carbon from organic sources.
The use of chemical agents directly on exposed body surfaces to destroy or inhibit vegetative pathogens is a. sterilization. b. antisepsis. c. disinfection. d. sanitization.
b. antisepsis.
Carboxysomes a. restrict nitrogenase access to oxygen b. concentrate CO2 and restrict RubisCO access to oxygen c. occur in cyanobacteria and plants d. are the site of the Calvin cycle and restrict RubisCO access to oxygen e. are the site of the Calvin cycle
b. concentrate CO2 and restrict RubisCO access to oxygen
Proteomic analysis of a microbial community indicated an abundance of phycobiliproteins. Which phototrophic group is likely active and abundant in this community? a. prochlorophytes b. cyanobacteria c. eukaryotic phototrophs d. green bacteria
b. cyanobacteria
All of the following are TRUE statements concerning binary fission of microbial cells EXCEPT a. elongation of the cell occurs and the chromosomes are pushed apart. b. daughter cells produced can be of different sizes. c. the chromosome of the cell is replicated. d. a septum is formed across the midline of the cell.
b. daughter cells produced can be of different sizes.
The Par system is necessary for a. formation of a replication fork in Escherichia coli. b. distribution of genetic material in replicating Caulobacter. c. elongation of bacillus prior to cell division. d. septum formation.
b. distribution of genetic material in replicating Caulobacter.
Organic micronutrients are commonly called __________. a. trace elements b. growth factors c. trace metals d. growth elements
b. growth factors
Proteins MinC, MinD, and MinE interact to a. initiate peptidoglycan synthesis. b. help guide FtsZ to the cell midpoint. c. assist chromosome segregation. d. determine cell shape.
b. help guide FtsZ to the cell midpoint.
In a culture grown in a chemostat (continuous culture), the best way to increase the yield of bacteria (numbers of cells per mL) would be to __________. a. increase the dilution rate (rate of addition of medium) b. increase the concentration of nutrients in the medium c. increase the temperature d. increase the growth rate
b. increase the concentration of nutrients in the medium
Fluorescent microscopy can be used to track the origin of replication (ori) on the chromosome during bacterial cell replication by performing all EXCEPT which of the following steps? a. introducing a sequence of DNA near the ori that will bind a fluorescent protein b. introducing a reporter gene into the chromosome next to the ori c. performing time-lapse fluorescent photomicroscopy of labeled cells during cell replication d. introducing a reporter gene into the chromosome that codes for a fluorescent protein that will bind to a specific DNA sequence near the ori
b. introducing a reporter gene into the chromosome next to the ori
Pasteurization is used to a. sterilize beverages. b. kill any pathogens present and retard spoilage. c. kill any pathogens present. d. retard spoilage. e. sterilize beverages and retard spoilage.
b. kill any pathogens present and retard spoilage.
The metabolic diversity of photosynthetic bacteria stems from different a. unrelated taxa capable of photosynthesis. b. light-harvesting complexes, electron donors, and organic compounds they produce. c. chlorophylls they can have and organic compounds they can produce. d. bacteriochlorophylls and pigments they contain.
b. light-harvesting complexes, electron donors, and organic compounds they produce.
What is a key difference between substrate level phosphorylation and oxidative phosphorylation? a. oxidative phosphorylation occurs in anaerobic organisms b. oxidative phosphorylation requires ATP synthase c. oxidative phosphorylation occurs when enough energy is released for phosphorylation of ADP d. substrate level phosphorylation requires oxygen e. all the above are key differences between substrate level phosphorylation and oxidative phosphorylation
b. oxidative phosphorylation requires ATP synthase
Two separate photosystems involved in electron flow is a hallmark of a. anoxygenic phototrophs. b. oxygenic phototrophs. c. green sulfur bacteria. d. purple bacteria.
b. oxygenic phototrophs.
A student has a pure culture of bacteria growing in a flask and wants to know how many living cells are in the culture at a given time. Which method should she employ to get an estimate? a. Any of these methods would work equally well in this case, assuming that standard curves are produced. b. plate counts c. microscopic counts d. turbidity measurements
b. plate counts
Which intermediate compound(s) in the citric acid cycle is/are often used for biosynthetic pathways as well as carbon catabolism? Select all that apply. a. citrate b. succinyl-CoA c. α-ketoglutarate d. oxaloacetate
b. succinyl-CoA c. α-ketoglutarate d. oxaloacetate
Microbial growth on the two-carbon acetate substrate invokes a. the citric acid cycle for aerobic catabolism. b. the glyoxylate pathway. c. both the citric acid and glyoxylate pathways. d. the glyoxylate and glycolysis pathways. e. glycolysis.
b. the glyoxylate pathway.
All of the following are true regarding energy-rich compounds EXCEPT a. Phosphoenolpyruvate is energy-rich. b. Hydrolysis of coenzyme A derivatives yields sufficient free energy to synthesize ATP. c. All phosphate bonds are energy-rich. d. The energy released in redox reactions is conserved in compounds that contain energy-rich phosphate or sulfur bonds. e. For longer term energy storage, microorganisms produce insoluble polymers that can be used to make ATP.
c. All phosphate bonds are energy-rich.
Which type of active transport protein uses one protein to pump two different molecules? a. Symport b. Uniport c. Antiport and Symport d. Antiport e. Uniport, Antiport, and Symport
c. Antiport and Symport
Distinguish how fermentation and respiration differ. a. Fermentation forms organic acids and takes place in the presence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen. b. Fermentation forms water and carbon dioxide and takes place in the presence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen. c. Fermentation forms organic acids and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen. d. Fermentation forms water and carbon dioxide and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen.
c. Fermentation forms organic acids and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen.
Penicillin inhibits which of the following molecules during cell division? a. MinE b. FtsZ c. FtsI d. FtsA e. FtsK
c. FtsI
Proton motive force generates an energized membrane where __________. a. both H+ and OH- accumulate on the outside of the membrane b. H+ accumulates on the inside of the membrane and OH- accumulates on the outside of the membrane c. H+ accumulates on the outside of the membrane and OH- accumulates on the inside of the membrane d. both H+ and OH- accumulate on the inside of the membrane
c. H+ accumulates on the outside of the membrane and OH- accumulates on the inside of the membrane
Which statement shows which adaptations are necessary for hyperthermophilic proteins to stay functional at temperatures above 80°C? a. Hyperthermophiles have decreased ionic bonds to stabilize the proteins. b. Hyperthermophiles have highly hydrophilic interiors to stabilize the proteins. c. Hyperthermophiles have increased ionic bonds to stabilize the proteins. d. Hyperthermophiles synthesize proteins with completely unique amino acid sequences to stabilize the proteins.
c. Hyperthermophiles have increased ionic bonds to stabilize the proteins.
Molecular adaptations to thermophily include all of the following EXCEPT a. High levels of cytoplasmic solutes b. Disulfide bonds in proteins of hyperthermophilic archaea. c. Proteins with fewer hydrophobic amino acids d. Proteins with increased number of ionic bonds e. Higher content of saturated, long chain fatty acids
c. Proteins with fewer hydrophobic amino acids
The number of organisms in a broth culture was determined using the standard plate count method (SPC) and spectrophotometry (SPEC). Which of the results below would you expect to see from each method? a. SPC = 12 × 106 cfu/ml; SPEC = 12 × 106 cfu/ml b. SPC = 12 × 107 cfu/ml; SPEC = 11 × 103 cfu/ml c. SPC = 12 × 106 cfu/ml; SPEC = 11 × 107 cfu/ml d. SPC = 100 cfu/ml; SPEC = 10 cfu/ml
c. SPC = 12 × 10^6 cfu/ml; SPEC = 11 × 10^7 cfu/ml
Consider solution A (pH 6) and solution B (pH 9). Which of the following statements is CORRECT? a. Solution A is 3 times more acidic than solution B. b. Solution A is 300 times more acidic than solution B. c. Solution B is 1,000 times more alkaline (basic) than solution A. d. Solution B is 3,000 times more alkaline (basic) than solution A.
c. Solution B is 1,000 times more alkaline (basic) than solution A.
How does the proton motive force lead to production of ATP? a. Oxidative phosphorylation of ADP by ATP synthase requires protons as cofactors in the reaction. b. ATPase requires one proton to make one ATP. c. Translocation of three to four protons drives the F0 component of ATPase, which in turn phosphorylates one ADP into ATP. d. Protons must be pumped against a concentration gradient from outside of the cell into the cell to rotate the F0 subunit of ATPase for the F1 subunit to make ATP.
c. Translocation of three to four protons drives the F0 component of ATPase, which in turn phosphorylates one ADP into ATP.
Which statement illustrates the chemical basis for the predominant type of fatty acids in the plasma membrane of a psychrophile? a. Saturated fats have kinked side chains that prevent tight packing as temperatures drop. b. Unsaturated fats have straight side chains that prevent tight packing as temperatures drop. c. Unsaturated fats have kinked side chains that prevent tight packing as temperatures drop. d. Saturated fats have straight side chains that prevent tight packing as temperatures drop.
c. Unsaturated fats have kinked side chains that prevent tight packing as temperatures drop.
A closed system, used for bacterial growth, where nothing is added and nothing is removed is called __________. a. a chemostat b. a continuous culture c. a batch culture d. a lag culture
c. a batch culture
A chemical that denatures proteins is most likely to be classified as a(n) ________ agent. a. bacteriostatic b. detergent c. bacteriocidal d. antiseptic
c. bacteriocidal
The only organisms that perform photosynthesis are ones that produce some form of a. carotenoids. b. phycocyanin. c. chlorophyll or bacteriochlorophyll. d. phycoerythrin.
c. chlorophyll or bacteriochlorophyll.
Which of the following proteins is mismatched with its eukaryotic homologue? a. MreB - actin b. FtsA - actin c. crescentin - tubulin d. FtsZ - tubulin
c. crescentin - tubulin
Which of the following molecules involved in electron transport has the most positive reduction potential? a. quinones b. NADH dehydrogenase c. cytochromes d. flavoproteins
c. cytochromes
Cultures of a bacterial species were incubated in a standard incubator, in an anaerobic jar, and in a candle jar (limited oxygen). After incubation, there was moderate growth of cultures in the candle and anaerobic jars, but heavy growth of the culture in the incubator. This species is a/n a. aerobe b. aerotolerant microbe c. facultative aerobe d. microaerophile e. anaerobe
c. facultative aerobe
At some of the lowest light concentrations, ________ can still grow well due to their ________, which effectively harvest photons for energy. a. purple bacteria / chlorosomes b. purple bacteria / antenna pigments c. green bacteria / chlorosomes d. green bacteria / antenna pigments
c. green bacteria / chlorosomes
Your laboratory supervisor has given you a plastic petri dish filled with soil to sterilize using radiation. What type of radiation will you use? a. microwave radiation b. UV radiation c. ionizing radiation d. solar radiation
c. ionizing radiation
In a batch culture, bacterial cultures typically exhibit four different phases of growth. In which phase are the cells rapidly synthesizing proteins, but cell numbers are not changing? a. exponential phase b. death phase c. lag phase d. stationary phase
c. lag phase
Which method can be used to determine the number of viable microorganisms in a sample? a. measuring total cell mass b. microscopic count c. measuring colony forming units per ml d. turbidity in a spectrophotometer e. all of the above
c. measuring colony forming units per ml
Which term is most relevant in describing the efficacy of an antimicrobial for use in a clinical setting? a. sterilization coefficient b. decimal reduction time c. minimum inhibitory concentration d. lethal dosage e. effective dose
c. minimum inhibitory concentration
Fermentation occurs when there is no usable external electron acceptor (like O2) available for respiration. The fermentation products are made following glycolysis as a result of reactions that __________. a. generate more ATP energy from the substrate b. get rid of toxic waste products generated during glycolysis c. oxidize NADH so that NAD+ can be reused again in glycolysis d. synthesize more NAD+ from substrate molecules
c. oxidize NADH so that NAD+ can be reused again in glycolysis
A halotolerant facultative aerobic bacterium would grow BEST in a ________ environment. a. oxygenated saline b. oxygen depleted saline c. oxygenated non-saline d. oxygen depleted non-saline
c. oxygenated non-saline
In contrast to chlorophylls, carotenoids function a. to convert reactive oxygen species into usable energy. b. as accessory pigments that enable absorption of energy from higher wavelengths c. primarily as photoprotection (but they also transfer some absorbed energy into reaction centers). d. to quench toxic oxygen species.
c. primarily as photoprotection (but they also transfer some absorbed energy into reaction centers).
What is the energy source for the import of an inorganic ion, such as Mg2+, through a simple symporter? a. concentration gradient of the transported molecule b. ATP c. proton motive force d. phosphoenolpyruvate e. any of the choices
c. proton motive force
Listeria monocytogenes is the agent of listeriosis, a serious infection caused by eating food contaminated with the bacteria.The bacteria may grow and accumulate in contaminated food stored in the refrigerator. L. monocytogenes is carried in the intestinal tract of 5-10% of the human population. Based on this information Listeria is a. a mesophile b. a psychromesophile c. psychrotolerant d. a psychrophile e. a xerophile
c. psychrotolerant
The Calvin cycle (select all that apply) a. occurs in carboxysomes. b. synthesizes glucose as its product. c. requires both ribulose bisphosphate carboxylase and phosphoribulokinase. d. utilizes both NAD(P)H and ATP. e. is responsible for the fixation of CO2 into cell material in many autotrophs.
c. requires both ribulose bisphosphate carboxylase and phosphoribulokinase. d. utilizes both NAD(P)H and ATP. e. is responsible for the fixation of CO2 into cell material in many autotrophs.
The number of colonies obtained in a plate count does NOT depend on the a. type of culture medium. b. inoculum volume. c. size of the colonies. d. incubation time.
c. size of the colonies.
The destruction or removal of all viable organisms is called a. sanitization. b. antisepsis. c. sterilization. d. Pasteurization. e. disinfection.
c. sterilization.
Which would NOT be an energy source for a hyperthermophile growing in a boiling hot spring? a. organic molecules b. sulfur c. sunlight d. hydrogen gas e. iron
c. sunlight
Which feature of anaerobic and aerobic respiration is different between the two catabolic strategies? a. electron donor and terminal electron acceptor b. electron donor c. terminal electron acceptor d. use of proton motive force e. use of electron transport
c. terminal electron acceptor
The reduction potential (E0′) of a substance reflects its tendency to donate or accept electrons. The larger the difference (ΔE0′) between the reduction potentials of the electron donor and the electron acceptor, __________. a. the more enzymes will be required to catalyze the reaction(s) b. the closer the substances are on the electron tower c. the greater the change in free energy (ΔG0′), and the greater the energy released d. the greater the change in free energy (ΔG0′), and the less energy is released
c. the greater the change in free energy (ΔG0′), and the greater the energy released
β-lactam antibiotics inhibit peptidoglycan a. autolysins. b. transglycosylation and transpeptidation. c. transpeptidation. d. transglycosylation. e. glycan tetrapeptide precursor formation.
c. transpeptidation.
Applying your knowledge of metabolism, glycolysis via the Embden-Myerhoff pathway starts with one molecule of glucose (6C) and produces a net total of __________. a. one pyruvate; 2 NADH; 4 ATP b. two pyruvate, 1 NADPH, 1 NADH, 1 ATP c. two pyruvate; 2 NADH; 2 ATP d. two pyruvate; 4 NADH; 2 ATP e. one pyruvate; 2 NADH; 2 ATP
c. two pyruvate; 2 NADH; 2 ATP
What is thought to be the maximum temperature for life to exist? a. 250°C b. 500°C c. 125°C d. 150°C
d. 150°C
What is the difference between a coenzyme and a prosthetic group? a. Coenzymes are essential for an enzymes function and prosthetic groups only enhance its reaction rate. b. Coenzymes require additional ions to bind to enzymes but prosthetic groups are able to directly interact with enzymes. c. Coenzymes are organic cofactors and prosthetic groups are inorganic cofactors. d. Coenzymes are weakly bound whereas prosthetic groups are strongly bound to their respective enzymes.
d. Coenzymes are weakly bound whereas prosthetic groups are strongly bound to their respective enzymes.
In which bacteria would you find MreB proteins and why? a. Neisseria gonorrhea, because it is coccus-shaped b. Mycoplasma pneumoniae, because it is pleomorphic c. Staphylococcus aureus, because it is coccus-shaped d. E. coli, because it is rod-shaped
d. E. coli, because it is rod-shaped
A common antimicrobial chemical (or chemicals) used as both an antiseptic and a general disinfectant is a. 70% alcohol. b. iodophors. c. hydrogen peroxide. d. Each of these chemicals at appropriate concentrations can be used as antiseptics or disinfectants.
d. Each of these chemicals at appropriate concentrations can be used as antiseptics or disinfectants.
Which is most abundant and active in divisome complexes? a. Crescentin b. DNA replication forks c. MinCD d. FtsZ e. MreB
d. FtsZ
All of the following are true of surface motility EXCEPT a. Flagella or archaella are not involved in surface motility. b. Gliding motility requires surface contact. c. Surface motility is well adapted for drier habitats. d. Gliding motility is characteristic of both Bacteria and Archaea e. Surface motility occurs via multiple mechanisms.
d. Gliding motility is characteristic of both Bacteria and Archaea
Proton motive force generates an energized membrane where __________. a.. both H+ and OH- accumulate on the inside of the membrane b. H+ accumulates on the inside of the membrane and OH- accumulates on the outside of the membrane c. both H+ and OH- accumulate on the outside of the membrane d. H+ accumulates on the outside of the membrane and OH- accumulates on the inside of the membrane
d. H+ accumulates on the outside of the membrane and OH- accumulates on the inside of the membrane
Which statement is FALSE? a. Respiration by both chemolithotrophs and chemoorganotrophs depends on oxidative phosphorylation for energy conservation. b. Chemolithotrophs use aerobic or anaerobic respiration. c. In chemolithotrophic metabolism, electrons from the oxidation of an inorganic electron donor directly enter an electron transport chain. d. Most chemolithotrophs are heterotrophic. e. Most chemolithotrophs use reverse electron transport to generate reducing power.
d. Most chemolithotrophs are heterotrophic.
Electron carriers used in electron transport chains are always found in membranes. Which one of the following statements is NOT a reason why electron transport chains are found in membranes? a. So that electron-only carriers can be arranged to alternate with electron-plus-proton carriers in the chain. b. So that the electron carriers can be oriented within the membrane such that protons are passed from one side of the membrane to the other. c. So that they can efficiently pass electrons in sequence from the carriers with the more negative reduction potentials to those with the more positive reduction potentials. d. So that they can transport NADH out of the cell to the periplasm.
d. So that they can transport NADH out of the cell to the periplasm.
Electron carriers used in electron transport chains are always found in membranes. Which one of the following statements is NOT a reason why electron transport chains are found in membranes? a. So that the electron carriers can be oriented within the membrane such that protons are passed from one side of the membrane to the other. b. So that electron-only carriers can be arranged to alternate with electron-plus-proton carriers in the chain. c. So that they can efficiently pass electrons in sequence from the carriers with the more negative reduction potentials to those with the more positive reduction potentials. d. So that they can transport NADH out of the cell to the periplasm.
d. So that they can transport NADH out of the cell to the periplasm.
A microbial ecologist wants to study a bacterium that is adapted to growth in lake water containing very low nutrient concentrations. Assuming that a suitable growth medium is available for this organism, which type of culture would be best to use for growing this organism in the lab? a. on Petri plates containing a low-nutrient medium b. This organism cannot be grown in the lab. c. a batch culture using a low-nutrient medium d. a chemostat using a low-nutrient medium
d. a chemostat using a low-nutrient medium
The function of NAD+/NADH in the cell is best described as __________. a. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between similar compounds b. a way to transport protons to the plasma membrane for energy generation in bacteria c. a way to transport electrons to the mitochondria for energy generation in bacteria d. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between dissimilar compounds
d. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between dissimilar compounds
Which statement regarding siderophores is FALSE? Siderophores ________. a. are organic molecules that bind iron tightly b. allow pathogens to outcompete host iron sequestration systems c. have applications in medicine for iron overload therapy d. are transporters that carry iron across cell membranes e. are produced by microorganisms and plants
d. are transporters that carry iron across cell membranes
Based on their energy source, primitive cells, such as those that might have evolved at deep sea vents, were most likely a. phototrophs, chemoorganotrophs or chemolithotrophs b. chemoorganotrophs or chemolithotrophs c. phototrophs d. chemolithotrophs e. chemoorganotrophs
d. chemolithotrophs
The curved-rod shape typical of Caulobacter is due to a. crescentin. b. MreB. c. FtsZ and crescentin d. crescentin and MreB. e. neither crescentin nor MreB.
d. crescentin and MreB.
Which choice illustrates best what occurs in the stationary phase of bacterial growth? a. cryptic growth, where the number of dead cells decreases while the number of new cells increases b. unbalanced growth, where the number of dead cells increases while the number of new cells decreases c. balanced growth, where the number of dead cells equals the number of new cells d. cryptic growth, where the number of new cells equals the number of dying cells
d. cryptic growth, where the number of new cells equals the number of dying cells
Optical density and viable cell concentration are LEAST proportional to each other during the a. lag phase. b. stationary phase. c. exponential growth phase. d. death phase.
d. death phase.
Relative to enzymes in mesophilic microorganisms, which of the following is NOT characteristic of enzymes in psychrophiles? a. fewer hydrogen bonds b. fewer ionic bonds c. decreased beta sheet content d. decreased alpha helix content
d. decreased alpha helix content
The Par system is necessary for a. formation of a replication fork in Escherichia coli. b. distribution of plasmids in E. coli c. elongation of bacillus prior to cell division. d. distribution of genetic material in replicating Caulobacter. e. septum formation.
d. distribution of genetic material in replicating Caulobacter.
The factor that most affects the thermostability of a protein is its a. highly hydrophobic core regions. b. number of hydrogen bonds. c. amino acid sequence. d. folding pattern. e. ionic surface interactions.
d. folding pattern.
Which type of organism will grow in low water activity but grows best at high water activity? a. alkaliphile b. osmophile c. extreme halophile d. halotolerant e. halophile
d. halotolerant
The addition of thioglycolate into a growth medium would LEAST support the growth of a(n) a. aerotolerant anaerobe. b. obligate anaerobe. c. facultative aerobe. d. microaerophilic aerobe.
d. microaerophilic aerobe.
All microorganisms require a. calcium, potassium, and magnesium. b. phosphorus, aluminum, and sodium. c. carbon, iron, and sodium. d. phosphorus, nitrogen, and sulfur.
d. phosphorus, nitrogen, and sulfur.
Which of the following statements regarding transport is FALSE? a. Transport occurs through a conformational change in the transmembrane transport protein. b. In group translocation, the transported substance is chemically modified during the transport process. c. ABC transport systems have high substrate affinity and thus help microorganisms survive in low nutrient environments. d. Energy sources for active transport include the proton motive force, ATP, or other energy-rich compound. e. All three mechanisms of active transport require multiple proteins.
e. All three mechanisms of active transport require multiple proteins.
In the process of binary fission in Bacteria, which action begins first? a. Formation of the divisome b. Cell separation c. Cell elongation d. Nucleoid segregation e. DNA replication
e. DNA replication
Which of the following statements regarding the cell growth cycle is FALSE? a. Microorganisms are most nearly uniform in chemical and physiological properties during exponential phase. b. The total number of viable microorganisms remains ~ constant in stationary phase because there is a balance between cell division and cell death. c. Stationary phase involves global change in cells, resembling differentiation. d. During death phase, viable cells may remain for months or even years. e. During the lag phase of microbial growth, the cells are metabolically inactive.
e. During the lag phase of microbial growth, the cells are metabolically inactive.
Which type of organism is least likely to have superoxide dismutase? a. Aerotolerant aerobe b. Facultative aerobe c. Microaerophile d. Obligate aerobe e. Strict anaerobe
e. Strict anaerobe
Spirochetes (Spirochaetota) move due to a. peritrichous flagella. b. gliding motility. c. twitching motility. d. type IV pili. e. endoflagella.
e. endoflagella.
A rod-shaped cell has a mutation such that when the temperature is raised above 37°C, it can no longer produce FtsZ. If you grew these cells at 40°C and then observed them via a Gram stain, you would see a. lysed cells, the cells would rupture b. small coccus-shaped cells c. large coccus-shaped cells. d. shorter rods than normal e. filaments
e. filaments
You discover a new transport system used by a newly discovered bacterial species. The sugars that are transported using this system are phosphorylated as they enter the bacterial cell. You would describe this transport system as _____. a. a symport b. simple transport c. an ABC transporter d. an antiport e. group translocation
e. group translocation