Microbiology Final Exam HW Questions

Which product of anoxic sewage treatment can be used to heat and power an entire water treatment facility? A. CH4 B. O2 C. CO2 D. H2

A. CH4

T/F: Phototrophic organisms in SIP experiments are often observed releasing 14CO2 as a way of measuring photosynthetic activity.

False

With increased levels of oxidizable materials, the biochemical oxygen demand (BOD) will A. increase. B. decrease. C. remain the same. D. increase or decrease depending on the nature of the materials involved.

A. increase.

Diptheria is caused by bacteria that have been infected by a bacteriophage. This bacteriophage is a lysogenic phage and contains the genes to produce the diphtheria toxin, which inhibits protein synthesis. Which of the following is the correct term for the phage while its genetic material is integrated into the bacterial chromosome? A. The genetic material is called a viroid. B. The genetic material is called a prion. C. The genetic material is called a transposon and the change in the host cell's properties is called competence. D. The genetic material is called a prophage and the change in the host cell's properties is called lysogenic conversion.

D. The genetic material is called a prophage and the change in the host cell's properties is called lysogenic conversion.

Ecologically, which transformation is most important in degrading chlorinated xenobiotics? A. reductive dechlorination B. chlorination C. dechlorination D. oxidative chlorination

A. reductive dechlorination

The number of Roseobacter in the ocean describes A. species abundance. B. species diversity. C. species prevalence. D. species richness.

A. species abundance.

A NASA ecologist wants to design an instrument to send to Mars on the next space probe to determine whether living organisms ever carried out carbon fixation on that planet. Suggest an assay that she could use on Martian soil samples. A. NanoSIMS B. MAR-FISH C. 13C/12C stable isotope analysis D. 34S/35S stable isotope analysis

C. 13C/12C stable isotope analysis

T/F: most wastewater treatment facilities employ methods designed to detect each pathogenic organism that may be present in a given sample.

FALSE

T/F: A toxoid is an attenuated form of a toxin that retains both its antigenicity and toxicity.

False

T/F: Chemoheterotrophic bacteria are primary producers.

False

T/F: Endotoxins are released in large amounts only when cells lyse.

True

Which of the following is a benefit of studying the human microbiome? A. It may allow for the development of personalized medical treatments. B. It may allow for increased recognition of disease biomarkers. C. It may allow for more finely targeted probiotics. D. All of these answer choices are possible benefits.

D. All of these answer choices are possible benefits.

Which of the following statements is TRUE about HIV infections? A. T-helper cells are greatly reduced in number. B. The cDNA can integrate into the host chromosome. C. The viral nucleocapsid of the virus enters the host cell when the viral and host membranes fuse. D. All of these statements are true.

D. All of these statements are true.

Which type of vaccine could possibly cause a person to develop the disease? A. Toxoid vaccine and inactivated killed vaccine B. Toxoid vaccine C. Inactivated killed vaccine D. Attenuated live vaccine

D. Attenuated live vaccine

What is meant by selective toxicity? A. Chemotherapeutic agents should work on many different targets on a pathogen. B. Chemotherapeutic agents should have only one mode of action. C. Chemotherapeutic agents should work on certain types of pathogens. D. Chemotherapeutic agents should act against the pathogen and not the host.

D. Chemotherapeutic agents should act against the pathogen and not the host.

New vaccine strategies resulting from progress in biochemistry and molecular biology include the production of A. synthetic peptide vaccines. B. DNA vaccines. C. recombinant vector vaccines. D. DNA, recombinant vector, and synthetic peptide vaccines.

D. DNA, recombinant vector, and synthetic peptide vaccines.

Which fluorescent molecule enables visualization of living microorganisms? A. DAPI B. SYBR® Green C. acridine orange D. GFP

D. GFP

The Spanish flu of 1918 was caused by an ________ influenza virus. A. H2N1 B. H2N2 C. H5N1 D. H1N1

D. H1N1

How would you label and separate the DNA of unknown methylotrophs in a sample? A. Use DGGE to separate the strands of DNA in the sample. B. Hybridize the DNA to FISH probes. C. Use T-RFLP to identify the methylotroph DNA in the sample. D. Incubate the sample with 13C-methane.

D. Incubate the sample with 13C-methane.

Widespread antimicrobial drug resistance is usually passed by A. horizontal gene transfer. B. gene splicing. C. heterologous gene expression. D. reverse transcription.

A. horizontal gene transfer.

According to the animation, surgical infections account for what percentage of nosocomial infections? A. 20% B. 8% C. 40% D. 15% E. 11%

A. 20%

A mutant of Rhizobium leguminosarum is able to survive and reproduce in the laboratory outside of plant roots, but can no longer initiate root nodule formation. What type of genes are most likely mutated in this mutant? A. rhz genes B. nif genes C. myc genes D. nod genes

D. nod genes

T/F: Cyclic di-guanosine monophosphate is upregulated as Pseudomonas aeruginosa cells are declining.

False

T/F: Pathogenicity islands are clusters of genes for virulence factors that are located together on the bacterial chromosome.

True

T/F: Reassortment of the genes of the influenza virus is facilitated by the fact that the genome is segmented.

True

T/F: Streptococcus pneumonia strains with capsules were called smooth because of their appearance on plates.

True

The diphtheria component of the DTaP vaccine is a(n) A. antitoxin. B. toxoid. C. antitoxoid. D. toxin.

B. toxoid.

Influenza virus targets ______________ A. oral cavity cells. B. gastrointestinal cells. C. throat epithelium. D. respiratory epithelium.

D. respiratory epithelium.

The respiratory tract has multiple systems to help protect against airborne diseases. Which of the following summarizes some of these systems? A. A mucociliary blanket to remove contaminants, secretion of lysozyme and other antimicrobial chemicals, and alveolar macrophages helps protect against airborne diseases. B. A filtering system of white and red blood cells, like that found in the spleen, helps protect against airborne diseases. C. Changes in air pressure as the air moves through the respiratory tract are sufficient to prevent pathogens from reaching the lower lungs. D. There are many antibodies within the lungs because it is so important to prevent infection.

A. A mucociliary blanket to remove contaminants, secretion of lysozyme and other antimicrobial chemicals, and alveolar macrophages helps protect against airborne diseases.

What are activity measurements? A. Activity measurements are collective estimates of the physiological reactions in an entire microbial community. B. Activity measurements are any measurements taken in situ. C. Activity measurements are an example of metagenomics, which can be used when genetic analysis is difficult. D. Activity measurements are any measurements taken in vitro.

A. Activity measurements are collective estimates of the physiological reactions in an entire microbial community.

How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic? A. Antibiotics can be used in aerosols, thereby entering the environment. B. Health care workers being treated with antibiotics may pass the antibiotic on to the patient. C. Visitors currently being treated with antibiotics can pass them on to the patient.

A. Antibiotics can be used in aerosols, thereby entering the environment.

Which of the following hypotheses could be tested using microautoradiography fluorescence in situ hybridization (MAR-FISH)? A. Archaea are the main autotrophs in marine water samples taken 300 m below the surface of the ocean. B. Bacteriorodopsin uses light energy to translocate protons. C. The ammonia monooxygenase gene is present in members of the phylum Verrucomicrobium. D. The microbial community of agricultural soils is more phylogenetically diverse than the microbial community of native prairie soils

A. Archaea are the main autotrophs in marine water samples taken 300 m below the surface of the ocean.

What type of nosocomial infection is likely to arise from intravenous catheterizations? A. Bacteremia B. Urinary tract C. Cutaneous D. Lower respiratory E. Surgical

A. Bacteremia

________ use inorganic electron donors released from deep-sea hydrothermal vents. A. Chemolithotrophs B. Photolithotrophs C. Chemoheterotrophs D. Photoheterotrophs

A. Chemolithotrophs

Most people experience several colds each year. Why is it that people do NOT develop immunity to the viruses that cause the common cold? A. Even when only the colds caused by rhinoviruses are considered, there is enough variation in the antigens presented by these viruses that they are often not recognized by the immune system even in an individual who has only recently recovered from a cold. B. Cold viruses produce capsules, shielding them from recognition by the immune system. C. Cold viruses do not stimulate T cells, which means that memory cells are not produced. Memory cells are needed to allow a more rapid response to future infection. D. Cold viruses do not stimulate B cells, which are responsible for producing memory cells to allow a more rapid response to future infection.

A. Even when only the colds caused by rhinoviruses are considered, there is enough variation in the antigens presented by these viruses that they are often not recognized by the immune system even in an individual who has only recently recovered from a cold.

What happens when mice grown in the absence of microbes are inoculated with healthy cecal material from other mice? A. Genes associated with glucose uptake, lipid absorption, and lipid transport are activated and the mice gain body fat without increasing energy intake. B. Genes associated with glucose uptake, lipid absorption, and lipid transport are activated and the mice gain body fat as a result of taking in more food. C. Genes associated with protein uptake, lipid break down, and lipid transport are deactivated and the mice lose body fat as a result of taking in less food. D. Genes associated with protein uptake, lipid break down, and lipid transport are activated and the mice lose body fat without changing their food intake.

A. Genes associated with glucose uptake, lipid absorption, and lipid transport are activated and the mice gain body fat without increasing energy intake.

When a person has previously been vaccinated against a viral pathogen, which cells are activated if that same pathogen re-enters the host's cells months or years later? A. Memory cytotoxic T cells B. Memory B cells C. Bacterial pathogens D. Helper T cells

A. Memory cytotoxic T cells

Compared with an endotoxin, would a bacterial exotoxin generally be more likely to function after it had been significantly heated? A. No, because exotoxins are heat-labile and less resistant to heating than endotoxins. B. Yes, because exotoxins are very heat stable compared to endotoxins. C. Yes, because exotoxins are proteins and non-living but endotoxins are part of the bacterial cell wall. D. No, because exotoxins are carbohydrates and endotoxins are proteins.

A. No, because exotoxins are heat-labile and less resistant to heating than endotoxins.

A farmer wants to stock small fish in a pond on his property, but the water looks a bit murky to him. He asks a microbiologist friend to analyze the pond water to see if fish could survive there. The microbiologist finds that the water has a very high BOD. Should she tell the farmer to stock the pond with fish? A. No; the pond is likely to be anoxic. B. No; the pond water is toxic. C. Yes; the pond water is high in nutrition for the fish. D. Yes; the pond is likely to be aerated.

A. No; the pond is likely to be anoxic.

How can health care workers reduce the occurrence of nosocomial infections? A. Practice more stringent aseptic techniques B. Administer all medications orally instead of through injections C. Limit the number of visitors who can see the patient D. Reduce the number of times they visit a patient

A. Practice more stringent aseptic techniques

For several months a graduate student has been working with a pure culture of a suspected bacterial pathogen in an attempt to determine whether it causes disease in various animal models. She had initially found that the organism was highly virulent in mice, but when she attempted to replicate her early experiments weeks later, all of the new experimentally infected mice survived. The student has brought her surprising findings to the lab's weekly research meeting. What advice could you give her? A. The bacterial strain may have become attenuated. B. The bacterial culture may not have been viable. C. The bacterial culture may have been contaminated. D. The mice may have become immune to the disease.

A. The bacterial strain may have become attenuated.

Which statement is TRUE about the fluid from the hydrothermal vents? A. The fluid contains large amounts of reduced inorganic materials. B. The fluid usually contains about equal amounts of organic and inorganic material. C. The fluid contains large amounts of organic material. D. The fluid contains large amounts of oxidized inorganic materials.

A. The fluid contains large amounts of reduced inorganic materials.

Why is U4+ a preferred form of uranium over U6+? A. U4+ is insoluble, so it will not contaminate groundwater. B. U4+ is soluble, so it can move from its initial site to other places and be diluted by groundwater. C. Uranite is insoluble; U4+ is soluble. D. U6+ is insoluble, which makes it difficult to work with.

A. U4+ is insoluble, so it will not contaminate groundwater.

A chemical that comes from outside the ecosystem is referred to as a(n) ________ chemical. A. allochthonous B. lithotrophic C. pleomorphic D. synthropic

A. allochthonous

The gut microbiota resembles the adult microbiota A. around age 3. B. by 12 months of age. C. by 1 month of age. D. around age 15.

A. around age 3.

All of the following are true of biofilms EXCEPT that __________. A. biofilms are composed of only one species at a time B. biofilms protect organisms from antibiotics C. biofilms form on virtually all submerged surfaces in nature D. biofilm formation and dispersal are regulated processes

A. biofilms are composed of only one species at a time

Increases in atmospheric carbon dioxide concentrations leads to acidification of the oceans as CO2 dissolves in the water and forms carbonic acid. This acidification is predicted to have a major effect on the carbon cycle, as well as the calcium and silica cycles, due to the roles of Ca+ and Si in __________. A. building the shells and frustules of microscopic algae and some animals B. the formation of carbonate rocks C. mercury oxidation D. the formation of fossil fuels

A. building the shells and frustules of microscopic algae and some animals

The calcium cycle is tightly coupled to the A. carbon cycle through calcium carbonate formation in ocean waters. B. silica cycle through calcium silicate formation in coastal ocean sediments. C. phosphorus cycle through calcium phosphate formation in sediments and rocks. D. nitrogen cycle because nitrogenase requires calcium ions.

A. carbon cycle through calcium carbonate formation in ocean waters.

Whooping cough is frequently observed in A. children under 6 months of age. B. individuals with compromised immunity. C. health care providers. D. elderly residents of nursing homes.

A. children under 6 months of age.

Staphylococcus aureus produces ________, an enzyme that results in the accumulation of fibrin around the bacterial cells. A. coagulase B. M protein C. collagenase D. lipase

A. coagulase

Geobacter sulfurreducens uses its pili to form direct connections with insoluble ferric iron particles. As the organism carries out respiration, the Fe3+ is acting as a(n) __________. A. electron acceptor B. carbon source C. electron donor D. micronutrient

A. electron acceptor

Phylogenetic analysis of microbial communities in nature using various PCR techniques has revealed that only a minority of phylotypes have been cultured from the environment and the most common phylotypes have not been grown in in the laboratory. This is due in part to __________. A. enrichment bias B. lack of sufficient sampling of the community C. poor technique D. the uncultured organisms' being rare in the community

A. enrichment bias

What technique(s) can be used to characterize the phylogenetic composition of a microbial community without culturing any of the members? A. fluorescent in situ hybridization (FISH) B. stable isotope techniques C. green fluorescent protein tagging D. radioisotope experiments

A. fluorescent in situ hybridization (FISH)

Metatranscriptomics and metaproteomics are favored over metagenomics when ________ is of more interest than ________. A. function or gene expression / gene presence B. gene presence / function or gene expression C. phylogeny / gene presence D. gene presence / phylogeny

A. function or gene expression / gene presence

Horizontal gene transfer between insects and their symbionts A. has been observed, but is considered a rare event. B. happens frequently because of coevolution. C. causes genome reduction in both the host and the symbiont. D. causes genome reduction in the symbiont and genome expansion in the host.

A. has been observed, but is considered a rare event.

Secondary disinfection of drinking water is necessary to A. maintain sufficient residual in the water distribution system to inhibit microbial growth. B. kill Cryptosporidium and other resistant pathogens. C. prevent the formation of biofilms on pipes in the water distribution system. D. neutralize taste- and odor-producing organic compounds.

A. maintain sufficient residual in the water distribution system to inhibit microbial growth.

Which technique would be used to estimate the concentration of naturally occurring Escherichia coli in a wastewater sample? A. most probable number (MPN) method B. agar dilution tube method C. laser tweezers method D. cell tagging using GFP method

A. most probable number (MPN) method

Ecological theory states that for every organism there is at LEAST one ________, and the microenvironment where the organism is most successful is called the ________. A. niche / prime niche B. community / population C. population / community D. prime niche / niche

A. niche / prime niche

Many nutrient cycles are coupled and changes in one cycle will affect another. This means that a change in the amount of carbon dioxide fixed is intimately affected by the amount of __________. A. nitrogen available in an ecosystem B. methane available in an ecosystem C. hydrogen available in an ecosystem D. oxygen available in an ecosystem

A. nitrogen available in an ecosystem

What role does Acidithiobacillus ferrooxidans play in the copper leaching process? A. oxidation of reduced iron (Fe2+) to oxidized iron (Fe3+) B. reduction of sulfate to sulfide C. oxidation of sulfide to sulfate D. reduction of oxidized iron (Fe3+) to reduced iron (Fe2+)

A. oxidation of reduced iron (Fe2+) to oxidized iron (Fe3+)

Epsilonproteobacteria are most dominant in hydrothermal vents because they A. oxidize sulfide and sulfur as electron donors. B. reduce nitrogen. C. bind divalent cations. D. use oxygen as electron acceptors.

A. oxidize sulfide and sulfur as electron donors.

Nitrous oxide (N2O) is a A. potent greenhouse gas that is a product of denitrification. B. direct product of ammonification. C. direct product of nitrogen fixation. D. potent greenhouse gas that is a product of nitrification.

A. potent greenhouse gas that is a product of denitrification.

As a microbiologist, you have been asked to advise a town council on the possible ways to remove PCB contaminants from the local groundwater. Which microbial process is most likely to have bioremediation potential in this case? A. reductive dechlorination B. aerobic dechlorination C. containment and stabilization D. leaching

A. reductive dechlorination

In insects, primary symbionts are ________, while secondary symbionts are ________. A. required for host reproduction / not required for host reproduction B. obligate symbionts / sometimes free-living C. able to replicate outside of the host / obligate symbionts D. heritable / not heritable

A. required for host reproduction / not required for host reproduction

An engineer working for the Peace Corps is helping a small town in Africa design a drinking water purification system. The raw water supply from the nearby river has high levels of suspended solids, dissolved organic carbon, and bacterial load. What would be the most effective order for the water treatment processes? A. sedimentation, coagulation, filtration, disinfection B. filtration, coagulation, sedimentation, disinfection C. disinfection, sedimentation, coagulation, filtration D. sedimentation, disinfection, coagulation, filtration

A. sedimentation, coagulation, filtration, disinfection

You would like to test the hypothesis that ammonia-oxidizing Archaea are more active and abundant than ammonia-oxidizing Bacteria in coastal marine water. What technique(s) or experiment(s) could you use to test this hypothesis? A. stable isotope probing using 15N labeled ammonia B. stable isotope ratios of ammonia and nitrite C. environmental proteomics D. fluorescent in situ hybridization (FISH)

A. stable isotope probing using 15N labeled ammonia

Among the recommendations from the Centers for Disease Control and Prevention to limit the development of antibiotic resistance are __________. A. to treat with the oldest, effective antimicrobial B. to treat with the newest, effective antimicrobial C. to treat with broad spectrum drugs D. to stop taking the antimicrobial as soon as symptoms disappear

A. to treat with the oldest, effective antimicrobial

The process of acquiring antibiotic resistance by means of bacteriophage activity is called A. transduction. B. R-plasmid acquisition. C. point mutation. D. transformation.

A. transduction.

All AB toxins have which of the following? A. two subunits B. hemolytic activity C. lipid A D. immunogenic properties

A. two subunits

Phylogenetic analyses of marine prokaryotic diversity in both shallow and deep-sea marine sediments have found that both types of sediments are dominated by A. Firmicutes. B. Proteobacteria. C. Planctomycetes. D. Chloroflexi.

B. Proteobacteria.

A soil clump has an oxic (oxygen containing) zone containing aerobic and facultatively aerobic organotrophs, and an anoxic zone containing fermentative bacteria, sulfate reducers, and denitrifyers. This soil clump has at least __________ different habitats, __________ different communities and __________ different guilds. A. 5, 5, 20 B. 2, 2, 5 C. 5, 2, 5 D. 2, 2, 20

B. 2, 2, 5

Assuming exposure to the same climate, which of the following aquatic systems would be most stratified? A. 50 m deep marine water fjord B. 300 m deep freshwater lake C. 200 m deep saltwater lake D. 20 m deep freshwater river

B. 300 m deep freshwater lake

What is the primary benefit of vaccination? A. Unvaccinated persons can never mount an immune response to a pathogen. B. An immune response will occur quicker upon future exposure to the pathogen. C. Vaccinated persons get used to the symptoms of a disease. D. Vaccines provide antibodies against the pathogen that persist forever in the body.

B. An immune response will occur quicker upon future exposure to the pathogen.

Decomposition of organic carbon ultimately results in the formation of __________. A. CH4 in aerobic environments and CO2 in anoxic environments B. CO2 in aerobic environments and CO2 plus CH4 in anoxic environments C. CO2 plus CH4 in aerobic environments and CH4 in anoxic environments D. CO2 in aerobic environments and CH4 in anoxic environments

B. CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

When Beijerinck enriched for nitrogen fixers, he inoculated soil into two types of liquid media: one containing mineral salts and mannitol but no nitrogen source (flask A), and one containing mineral salts, mannitol, and an ammonium salt (flask B). After incubation in the presence of air, what types of organisms did he expect to find in each flask? A. Flask A would contain ammonium utilizers, and flask B would contain nitrogen fixers that could grow without the presence of ammonium. B. Flask A would contain nitrogen fixers that could grow both without ammonium; flask B would not contain nitrogen fixers but would contain organisms that could use ammonium. C. Flask A would contain nitrogen fixers that could not tolerate the presence of ammonium; flask B would contain ammonium utilizers. D. Flask A would contain ammonium utilizers and flask B would contain nitrogen fixers that could not tolerate the presence of ammonium.

B. Flask A would contain nitrogen fixers that could grow both without ammonium; flask B would not contain nitrogen fixers but would contain organisms that could use ammonium.

Riftia tube worms contain unusual hemoglobins that bind(s) A. high concentrations of O2 produced by their photosynthetic symbionts. B. H2S and O2 in order to transport these chemicals to their bacterial symbionts. C. ammonia that their bacterial symbionts produce. D. sulfate to transport this ion away from their bacterial symbionts.

B. H2S and O2 in order to transport these chemicals to their bacterial symbionts.

Some mercury-resistant bacteria can convert toxic forms of mercury to less toxic forms using the mer operon under transcriptional regulation the merR protein. What molecule would you predict binds to merR to cause it to act as a repressor or as an activator of transcription for this operon? A. NADH B. Hg2+ C. MerP periplasmic binding protein D. H0

B. Hg2+

One group of medications used to treat HIV infections is the reverse transcriptase inhibitors. There are two types of these medications, nucleoside reverse transcriptase inhibitors (like AZT) and non-nucleoside reverse transcriptase inhibitors. AZT resembles thymine and is inserted into DNA during replication, leading to the termination of replication. Non-nucleoside reverse transcriptase inhibitors bind to reverse transcriptase and inhibit it in that manner. Non-nucleoside reverse transcriptase inhibitors tend to have fewer side effects. Which of the following best describes why this is the case? A. Non-nucleoside reverse transcriptase inhibitors are less likely to stimulate cell growth. B. Nucleoside reverse transcriptase inhibitors may interfere with DNA replication by the host, not just by the virus. C. HIV can rapidly develop resistance to nucleoside reverse transcriptase inhibitors. D. Non-nucleoside reverse transcriptase inhibitors are less specific and therefore more effective.

B. Nucleoside reverse transcriptase inhibitors may interfere with DNA replication by the host, not just by the virus.

________ are the main primary producers in freshwater environments. A. Heterotrophic microorganisms B. Phototrophic microorganisms C. Viral microorganisms D. Chemolithotrophic microorganisms

B. Phototrophic microorganisms

Based upon microbiome projects, the dominant microbial species on the skin is A. Corynebacterium species. B. Propionibacterium species. C. Staphylococcus species. D. Streptococcus species.

B. Propionibacterium species.

Autoimmune diseases sometimes develop shortly after an infection. This is the case with rheumatic fever. Which of the following is the most likely reason that there is often a relationship between autoimmune disorders and infection? A. Pathogens (like S. pyogenes) that can cause multiple types of diseases cause a stronger immune response, which can lead to an autoimmune disease. B. Some pathogens, like the rheumatogenic strains of S. pyogenes, contain antigens that resemble normal cell surface proteins. As the immune system responds to them, it attacks the cells with similar antigens as well. C. The immune system becomes highly active during an acute infection and is less selective about what it attacks D. Some exotoxins are superantigens and elicit a strong immune response

B. Some pathogens, like the rheumatogenic strains of S. pyogenes, contain antigens that resemble normal cell surface proteins. As the immune system responds to them, it attacks the cells with similar antigens as well.

Why are some xenobiotics biodegraded slower than crude oil and petroleum products? A. Chlorinated compounds are so toxic that biodegradation is not possible. B. Some xenobiotics are novel compounds that differ from naturally occurring chemicals, thus microorganisms have not yet evolved to effectively degrade them. C. Xenobiotics were designed to inhibit microbial growth. D.Only cometabolic microbial processes degrade xenobiotics.

B. Some xenobiotics are novel compounds that differ from naturally occurring chemicals, thus microorganisms have not yet evolved to effectively degrade them.

Native peoples often experience an increase in the incidence of dental caries after they are introduced to imported processed foods. This finding could be explained by the fact that __________. A. Only purified sucrose and fructose can be fermented or produce acids in the oral cavity. B. Sucrose is required for the production of adhesive dextran by Streptococcus mutans. C. Lactobacilli require sucrose in order to form biofilms on tooth surfaces. D. Sucrose and other purified sugars cause pitting of the tooth surfaces.

B. Sucrose is required for the production of adhesive dextran by Streptococcus mutans.

If the biochemical oxygen demand (BOD) of a lake is very high, how will that affect the aquatic life in the lake? A. There will be more oxygen available for the aquatic life due to the microbial activity. B. There will be less oxygen available for the aquatic life due to the microbial activity. C. There will be more oxygen available for the aquatic life but much less oxygen available to the microbial populations. D. The BOD does not have an impact on available oxygen in the lake.

B. There will be less oxygen available for the aquatic life due to the microbial activity.

What is the hallmark of a conjugated vaccine? A. They contain only the non-pathogenic elements of a pathogen, not the entire cell. B. These vaccines contain weakly antigenic elements plus a more potent antigenic protein. C. They contain the DNA from a pathogenic virus.

B. These vaccines contain weakly antigenic elements plus a more potent antigenic protein.

Considering that they require an oxygen-free environment, how do obligate anaerobes survive in the human body? A. They are able to use enzymes to convert reactive oxygen species to harmless molecules. B. They are able to survive in places where aerobic organisms quickly use the available oxygen. They can also survive in areas with impaired blood flow (reducing oxygen availability). C. Obligate anaerobes are unable to survive in the human body. D. They live inside of organelles, such as peroxisomes.

B. They are able to survive in places where aerobic organisms quickly use the available oxygen. They can also survive in areas with impaired blood flow (reducing oxygen availability).

A woman mentions to her physician during a prenatal check-up that she plans to clean her house from "top-to-bottom" before the baby arrives, and intends to protect her newborn from as many "germs" as possible to prevent any possible infections. If you were the physician, how would you advise this patient? A. Cleanliness is a good thing in general. In particular, the patient should consider sterilizing as much of the infant's food and water as possible, since diarrheal diseases can be very serious in infants. B. Too much cleanliness can be a bad thing for an infant, as the bacteria they acquire at an early age help to "train" the immune system to correctly recognize pathogens but not attack beneficial bacteria in the body. Attacking the "normal" bacteria and nonharmful substances can cause too much inflammation, allergies, or asthma later in life. C. Her plan is a good one, as long as she plans to deliver her child vaginally rather than by Cesarean section and if she breast-feeds her child. During a vaginal delivery the infant will be dosed with all of the bacteria it needs to get a good start on colonizing its "normal" bacteria, and breast milk foster the growth of the right ones. D. The patient's plan is a good one. You never know when the infant might encounter a serious pathogen. Since infants do not have a well-developed immune system yet, pathogens can be very dangerous. She should disinfect all surfaces in her home daily.

B. Too much cleanliness can be a bad thing for an infant, as the bacteria they acquire at an early age help to "train" the immune system to correctly recognize pathogens but not attack beneficial bacteria in the body. Attacking the "normal" bacteria and nonharmful substances can cause too much inflammation, allergies, or asthma later in life.

The insect symbiont Wolbachia can be used to suppress disease transmission by mosquitoes because A. Wolbachia supplies essential nutrients to the mosquito Culex quinquefasciatus. B. Wolbachia-infected male mosquitoes sterilize uninfected female mosquitoes. C. only Wolbachia-infected mosquitoes can transmit viral diseases such as dengue fever. D. Wolbachia infections can spread rapidly through a mosquito population, killing all the mosquitoes.

B. Wolbachia-infected male mosquitoes sterilize uninfected female mosquitoes.

While most of the oil spilled into the Gulf of Mexico from the Deepwater Horizon drilling rig in 2010 has disappeared, some of the oil spilled from the Exxon Valdez oil tanker into Prince William Sound, Alaska, in 1989 still remains in the coastal sand and sediments. What possible differences in these two spills could account for the different rates of petroleum degradation? A. the types of bacteria present and the amount of oxygen in the water B. ambient temperatures and the types of hydrocarbons present C. seawater salt composition and types of bacteria D. the amount of oil spilled and the seawater salts composition

B. ambient temperatures and the types of hydrocarbons present

Which are the most dominant chemolithotrophs in pelagic waters? A. Prochlorococcus B. ammonia-oxidizing Archaea C. ammonia-oxidizing Bacteria D. sulfate-reducing Bacteria

B. ammonia-oxidizing Archaea

Analyses of sulfur isotopes have been used as evidence against life on the Moon, because the sulfides in lunar rocks have A. an isotope composition most similar to marine mud, which is enriched in 34S. B. an isotope composition most similar to igneous rocks. C. exactly equal amounts of 34S and 32S. D. an isotope composition most similar to marine sulfate, which is enriched in 34S.

B. an isotope composition most similar to igneous rocks.

A pathogen must __________ in order for it to cause disease. A. enter a host B. attach and multiply C. attach D. secrete a toxin

B. attach and multiply

An organism living in the bottommost region of a body of water is described as being A. litoral. B. benthic. C. neritic. D. pelagic.

B. benthic.

The strategy for bioremediation of large sites contaminated by inorganic pollutants like toxic metals and radionuclides is usually to __________. A. completely remove the contaminants from the site B. contain the pollutants by converting them into a less mobile form C. break down the pollutants to less harmful products D. completely oxidize the pollutants to carbon dioxide and water

B. contain the pollutants by converting them into a less mobile form

By isolating total community RNA, using reverse transcriptase to make cDNA copies of it, and then sequencing the cDNA, ecologists can __________. A. determine the community genomic potential at the moment of sampling B. determine the community genome expression at the moment of sampling C. determine the community metabolic activity at the moment of sampling D. determine the community genome translation at the moment of sampling

B. determine the community genome expression at the moment of sampling

When treating a fungal infection, the best target for selective toxicity would be __________. A. polypeptide elongation B. ergosterol synthesis C. cell division proteins D. lipid synthesis

B. ergosterol synthesis

Bacteria, such as Leptothrix, must have a mechanism to manage the end products when utilizing iron for oxidation, because __________. A. A large amount of energy can be conserved from the oxidation of ferrous iron to ferric iron. B. ferric iron is insoluble and will build up in or on the cell C. A large amount of energy can be conserved from the oxidation of ferric iron to ferrous iron. D. ferrous iron is insoluble and will build up in or on the cell

B. ferric iron is insoluble and will build up in or on the cell

Which of the following microbial groups is most resistant to desiccation due to their cell wall? A. viruses B. gram-positive C. gram-negative D. mycoplasmas

B. gram-positive

Agricultural application of nitrogen fertilizer A. reduces global warming by increasing the storage of carbon dioxide in plant biomass. B. increases global warming by increasing the production of nitrous oxide (N2O) by denitrification in agricultural soils. C. increases global warming by increasing microbial respiration in agricultural soils. D. has little to no effect on the carbon cycle.

B. increases global warming by increasing the production of nitrous oxide (N2O) by denitrification in agricultural soils.

The primary metal sulfides emitted from the black smokers are ________ sulfides. A. copper B. iron C. magnesium D. zinc

B. iron

Which of the following is a major growth-limiting micronutrient that influences microbial growth? A. sugar B. iron C. vitamin K D. water

B. iron

Toxic shock syndrome __________. A. is associated only with Staphylococcus species B. is life-threatening because of the superantigen toxin produced C. is life-threatening because of the endotoxin produced D. is always associated with tampon usage

B. is life-threatening because of the superantigen toxin produced

Which approach would help to identify biologically produced sulfur in a sediment sample? A. microelectrodes B. isotopic fractionation C. microautoradiography D. enrichment

B. isotopic fractionation

Helicobacter pylori is a bacterium found in the stomachs of roughly half of the human population. It is considered to be a pathogen because __________. A. it is found in the stomach mucosa rather than the lumen B. it can cause chronic inflammation C. it is the only bacterium found in the human stomach D. when present, it accounts for the vast majority of stomach microbial biomass

B. it can cause chronic inflammation

The role of the iron-containing leghemoglobin in the rhizobial root nodules of soybeans is to __________. A. carry iron to the rhizobial bacteria B. lower the amount of free O2 in the root nodule C. carry O2 from the leaves to the root nodule D. carry O2 from the root nodule to the leaves

B. lower the amount of free O2 in the root nodule

Both ammonium (NH4+) and nitrate (NO3-) are assimilated by primary producers, but ammonium is the preferred form of nitrogen for fertilizers used in agriculture because __________. A. ammonium is converted to nitrate by microbial nitrification B. nitrate leaches out of soils easily due to its negative charge C. ammonium leaches out of soils easily due to its positive charge D. ammonium does not cause eutrophication (algal blooms) if it enters aquatic ecosystems

B. nitrate leaches out of soils easily due to its negative charge

Which of the following is the first, or initiator, reaction in acid mine drainage and leaching? A. microbial sulfate reduction B. oxidation of reduced sulfides to sulfate and the release of reduced iron (Fe2+) C. rapid oxidation of sulfides to sulfate by oxidized iron (Fe3+) D. rapid spontaneous reduction of oxidized iron (Fe3+)

B. oxidation of reduced sulfides to sulfate and the release of reduced iron (Fe2+)

Biomass generation due to heterotrophic organisms is called ________ production. A. auxotrophic B. secondary C. regulatory D. primary

B. secondary

Which metabolic strategy is most common in chemolithotrophic mats? A. nitrate reduction B. sulfur oxidation C. iron oxidation D. ammonia oxidation

B. sulfur oxidation

Based on your knowledge of hydrocarbon degradation, what factors most likely limited the rate of petroleum degradation after the Exxon Valdez oil spill off the coast of Alaska? A. inorganic nutrient concentrations B. temperature and inorganic nutrient concentrations C. temperature D. salt concentration

B. temperature and inorganic nutrient concentrations

One important difference between the C, N, and S cycles and the P, Ca, and Si cycles is that A. P, Ca, and Si are NOT cycled in terrestrial environments. B. the P, Ca, and Si cycles do NOT involve redox changes or gaseous forms that can alter Earths atmospheric chemistry. C. the P, Ca, and Si cycles do NOT involve microbial activity. D. the P, Ca, and Si cycles are NOT affected by global warming or other human activity.

B. the P, Ca, and Si cycles do NOT involve redox changes or gaseous forms that can alter Earths atmospheric chemistry.

Microbial leaching of valuable metals from low-concentration ores is carried out in open-air leaching dumps for copper recovery, but in closed bioreactors for gold recovery because __________. A. the microbes used for gold leaching are obligate anaerobes B. the bioreactor prevents release of toxic waste products from gold-containing ores C. the bioreactor prevents the loss of any valuable gold D. more oxygen is required for copper leaching

B. the bioreactor prevents release of toxic waste products from gold-containing ores

Radioisotopes are useful when A. very high sensitivity is required. B. very high sensitivity is required, turnover rates need to be determined, and the fate of portions of particular molecules need to be followed. C. turnover rates need to be determined. D. the fate of portions of particular molecules need to be followed.

B. very high sensitivity is required, turnover rates need to be determined, and the fate of portions of particular molecules need to be followed.

It is difficult to attain good selective toxicity with antiviral drugs because of the fact that __________. A. viruses can hide in an envelope from the host cell B. viruses require host cells to replicate themselves C. viruses are not living organisms D. viruses are not cells

B. viruses require host cells to replicate themselves

Both active and passive immunotherapy are based on antibody-mediated responses. Which of the following statements about active immunotherapy is true? A. Unlike passive immunotherapy, active immunotherapy does not require the use of a booster injection. B. Active immunotherapy can lead to serum sickness. C. Active immunotherapy provides long-term protection due to the generation of memory cells. D. Active immunotherapy provides immediate protection against infection.

C. Active immunotherapy provides long-term protection due to the generation of memory cells.

What is the function of boosters? A. Boosters help to kill the pathogens used in inactivated killed vaccines. B. Boosters are the highly antigenic portions of the conjugated vaccines. C. Boosters are injections that are given periodically to maintain immunity. D. Boosters are vaccines containing no pathogenic portions of the pathogen.

C. Boosters are injections that are given periodically to maintain immunity.

Quinolones and fluoroquinolones act against what bacterial target? A. Cell walls B. Metabolic pathways unique to bacteria C. DNA gyrase D. Bacterial ribosomes E. Cell membranes

C. DNA gyrase

________ are toxic proteins released from the pathogen during normal growth. A. Macrotoxins B. Microtoxins C. Exotoxins D. Endotoxins

C. Exotoxins

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug? A. They are less expensive that other chemotherapeutic agents. B. Bacteria are especially sensitive to these compounds. C. Humans and other animal hosts lack peptidoglycan cell walls. D. The drugs also work against DNA gyrase.

C. Humans and other animal hosts lack peptidoglycan cell walls.

Antibiotic resistance is a major concern as microbes can rapidly develop resistance when antibiotics are not used appropriately. Which of the following examples best describes how this occurs? A. Exposure to too much of an antibiotic causes resistance. B. Microbes respond to the presence of antibiotics by deliberately developing resistance mechanisms. C. In any population of microbes, some individuals may have resistance genes. When exposed to an antibiotic, there is selection for the microbes that have these genes. D. Antibiotics are mutagenic. They cause mutations, like other mutagenic chemicals.

C. In any population of microbes, some individuals may have resistance genes. When exposed to an antibiotic, there is selection for the microbes that have these genes.

A clinical lab was not able to isolate any pathogenic bacteria from a patient suffering from a high fever and elevated white blood cell count. The physician suspects a viral infection may be to blame. What detection assay may the lab want to try next? A. immunofluorescence B. an immunoblot (Western blot) assay C. PCR followed by a nucleic acid hybridization technique to detect viral DNA or RNA D. an agglutination test

C. PCR followed by a nucleic acid hybridization technique to detect viral DNA or RNA

Which of the following mutations would not result in antibiotic resistance? A. Missense mutation B. Nonsense mutation C. Silent mutation D. Frameshift insertion E. Frameshift deletion

C. Silent mutation

A small farm pond containing many species of microorganisms (bacteria, cyanobacteria, algae, and protozoa) was perturbed when runoff from a manure pile entered the pond. The added nutrients soon turned the water green due to a bloom of cyanobacteria. How did this affect the microbial community in the pond? A. Species richness decreased and species abundance decreased. B. Species richness increased and species abundance increased. C. Species richness decreased and species abundance increased. D. Species richness increased and species abundance decreased.

C. Species richness decreased and species abundance increased.

The causative agent of streptococcal pharyngitis, also known as strep throat, is A. Streptococcus mutans. B. Streptococcus lactis. C. Streptococcus pyogenes. D. Streptococcus pneumoniae.

C. Streptococcus pyogenes.

The Hepatitis B vaccine is which type of vaccine? A. Inactivated killed vaccine B. DNA vaccine C. Subunit vaccine D. Toxoid vaccine

C. Subunit vaccine

What is meant when a bacterium is said to become "resistant" to an antibiotic? A. The antibiotic kills or inhibits the bacterium. B. The antibiotic is metabolized by the bacterium, providing more energy for growth of the cell. C. The bacterium is neither killed nor inhibited by the antibiotic. D. The antibiotic mutates in a way that benefits the bacterium.

C. The bacterium is neither killed nor inhibited by the antibiotic.

Which of the following is NOT true about breast fed infants compared with those fed formula? A. They have greater numbers of Bifidobacterium longum. B. They have greater numbers of Citrobacter spp. C. They have greater numbers of Clostridium difficile. D. They have greater numbers of Enterobacter cloacae.

C. They have greater numbers of Clostridium difficile.

What does a vaccine contain? A. Live active pathogens B. B cells against a pathogen C. Weakened or killed pathogen or parts of a pathogen D. T cells against a pathogen

C. Weakened or killed pathogen or parts of a pathogen

Why would using nitrogenous fertilizer near a body of water affect the organisms in the body of water? A. It would not affect the organisms in the water, only those in the soil where the fertilizer is applied. B. When runoff enters the body of water, the nitrogen level significantly decreases, which increases the activity of the microorganisms there and upsets the balance of the ecosystem. C. When runoff enters the body of water, the nitrogen level significantly increases, which increases the activity of the microorganism there and upsets the balance of the ecosystem. D. When runoff enters the body of water, the nitrogen level significantly increases, which decreases the activity of the microorganisms there and upsets the balance of the ecosystem.

C. When runoff enters the body of water, the nitrogen level significantly increases, which increases the activity of the microorganism there and upsets the balance of the ecosystem.

When measuring microbial community metabolic activity, __________ is always necessary. A. DNA extraction and sequencing B. radioisotopes C. a killed control D. enrichment culture

C. a killed control

The mouse model of obesity suggests that __________ is linked to increased body mass. A. a reduction in Firmicutes B. a reduction in methanogens C. a reduction in Bacteroidetes D. All of the listed responses are correct.

C. a reduction in Bacteroidetes

R-plasmids are most likely acquired via A. translation. B. transformation. C. bacterial conjugation. D. transduction.

C. bacterial conjugation.

Influenza A virus can be identified by which of the following surface glycoproteins? A. HA B. NA C. both HA and NA D. M protein

C. both HA and NA

Clostridium perfringens causes gas gangrene, a serious infection of the muscle tissues that can lead to amputation. Clostridium are Gram-positive endospore-formers and obligate anaerobes that are killed when exposed to oxygen. Which of the following virulence factors would be most helpful to this organism in establishing an infection? A. endotoxin B. a neurotoxin C. collagenase, an enzyme that destroys collagen, which is a major protein of connective tissues D. nuclease, an enzyme that breaks down nucleic acids

C. collagenase, an enzyme that destroys collagen, which is a major protein of connective tissues

Obligate anaerobes are likely to be found in the __________. A. mouth B. nasal cavity C. colon D. urogenital tract

C. colon

The colon has been described as a living fermentation vessel. Which type of culture system would it most resemble? A. batch culture B. immobilized cell culture C. continuous culture D. None of the listed responses is correct.

C. continuous culture

Sulfide is toxic to respiring organisms, because it can combine with metals present in ________ that serve a critical function in respiration. A. NADH B. oxidases C. cytochromes D. glycolysis enzymes

C. cytochromes

Sudden nutrient perturbations in an environment generally ________ the overall prokaryotic diversity. A. replicate B. maintain C. decrease D. increase

C. decrease

C. difficile infections are on the rise, both in elderly hospitalized patients receiving antibiotics and in younger populations having no previous contact either with a hospital environment or antibiotics. What is the most effective treatment for chronic C. difficile infections? A. high doses of antibiotics B. surgical removal of the colon if antibiotic therapy fails C. fecal transplants from a healthy donor D. medical management with intravenous fluids to prevent dehydration and shock

C. fecal transplants from a healthy donor

Bacterial symbionts most often provide marine invertebrates in hydrothermal vents with A. cellulolytic enzymes to help digest plant material. B. sulfate and other sulfur compounds. C. fixed carbon dioxide in the form of organic compounds. D. fixed nitrogen in the form of ammonia.

C. fixed carbon dioxide in the form of organic compounds.

Microarrays are useful for assessing A. gene expression only. B. enzyme activity. C. gene expression and the presence of specific rRNA sequences. D. the presence of specific rRNA sequences only.

C. gene expression and the presence of specific rRNA sequences.

Blood agar is an example of amedium that supports the growth of many microbes. Medium that supports a wide variety of growth is called ________ medium. A. halophilic B. stable C. general-purpose D. selective

C. general-purpose

Genomic analysis of Prochlorococcus has revealed A. that no regions are shared between cultured representatives and environmental populations. B. the presence of bacteriorhodopsin. C. high levels of gene conservation between cultured representatives and environmental populations. D. complete congruence of genes and genome structure within the same phylotype.

C. high levels of gene conservation between cultured representatives and environmental populations.

The phylogenetic diversity analysis of complex microbial communities often targets small subunit (SSU) ribosomal RNA genes. This is because rRNA is found in all organisms and __________. A. is easier to extract from samples B. has more genes than mRNA C. is highly conserved over evolutionary time D. is made by cells only at certain times

C. is highly conserved over evolutionary time

Based on comparative studies of agricultural soils or polluted soils compared with undisturbed soils, disturbance of soil microbial communities tends to lead to __________. A. higher microbial abundance B. no change in microbial community composition C. lower prokaryotic diversity D. greater microbial metabolic activity

C. lower prokaryotic diversity

From the aquatic systems below, where are heterotrophic Bacteria the most abundant? A. open ocean B. deep sea C. marine coastal waters D. Sargasso Sea

C. marine coastal waters

The two major forms of carbon that remain following microbial degradation are A. lignin and fossil fuels. B. organic matter and hydrocarbons. C. methane and carbon dioxide. D. methane, organic matter, and fossil fuels.

C. methane and carbon dioxide.

To prevent the souring of crude oil, ________ is added to oil well injection water to encourage ________ instead of ________. A. oxygen / aerobic respiration / sulfate reduction B. sulfate / sulfate reduction / nitrate reduction C. nitrate / nitrate reduction / sulfate reduction D. sulfate / sulfate reduction / fermentation

C. nitrate / nitrate reduction / sulfate reduction

Which of the following can be completely degraded to carbon dioxide by microorganisms? A. chlorinated organics B. uranium C. petroleum and chlorinated organics D. petroleum

C. petroleum and chlorinated organics

Thirty organisms containing the same phylogenetic marker, with identical or similar orthologous genes, are all considered to be within the same A. functional group. B. species. C. phylotype. D. phylogenetic tree.

C. phylotype.

Opportunistic pathogens such as Legionella, Pseudomonas, and Mycobacterium species have the ability to grow within ________, which may enhance their ability to survive in water distribution systems. A. human saliva B. fish C. protists D. UV irradiated water

C. protists

The inflammatory response to Corynebacterium diphtheriae infection results in the production of a lesion called a A. lesion. B. chancre. C. pseudomembrane. D. pustule.

C. pseudomembrane.

Staining methods are suitable for obtaining A. information about physiology from natural samples. B. phylogenetic information from natural samples. C. quantitative information from natural samples. D. neither qualitative nor quantitative information from natural samples.

C. quantitative information from natural samples.

What would the result be when a soil is supplemented with S0? A. organic carbon production due to anaerobes B. syntrophic utilization of sulfite C. soil acidification due to chemolithotrophs D. dimethyl sulfide production due to mixotrophs

C. soil acidification due to chemolithotrophs

Which of the following is NOT a staphylococcal disease? A. acne B. boils C. strep throat D. meningitis

C. strep throat

Industrial production of nitrogenous fertilizers from N2 now equals or exceeds the amount of nitrogen fixation carried out by microbes in the biosphere. The resulting increase in primary production is an example of the fact that __________. A. there is a fixed quantity of N on Earth B. N is generally not a limiting nutrient for primary production C. the C and N cycles are closely coupled D. synthetic fertilizers work better than natural N sources for primary production

C. the C and N cycles are closely coupled

When a patient is treated with antibiotics, __________. A. mutations occur in all of the bacterial cells B. sensitive bacterial cells multiply uncontrollably C. the drug will kill or inhibit the growth of all of the sensitive bacterial cells D. the drug will kill or inhibit the growth of all of the resistant bacterial cells E. mutations will occur in the sensitive bacterial cells, but not in the resistant bacterial cells

C. the drug will kill or inhibit the growth of all of the sensitive bacterial cells

Which of the following is TRUE of Riftia tube worm symbionts? A. they have an unusually small genome, even for a symbiont B. they have never been maintained in laboratory culture C. they have a free-living stage D. they are obligate symbionts

C. they have a free-living stage

Single-cell genomics may help us A. understand the physiology of uncultured microbes. B. develop better enrichment culture methods. C. understand the physiology of uncultured microbes and develop better enrichment culture methods. D. predict which microbes will be abundant based on the environmental conditions.

C. understand the physiology of uncultured microbes and develop better enrichment culture methods.

Why is polymyxin only used on the skin? A. It can disrupt the metabolic pathways found in humans. B. It has no effect on bacteria that live in the GI tract. C. It is sensitive to degradation by acid, making oral delivery unsuitable. D. It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.

D. It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.

Some microbial transformations of mercury yield more toxic forms of mercury, including the most toxic form, methylmercury (CH3Hg+). Which of the following properties of methylmercury in an aquatic ecosystem would be most problematic for humans? A. Methylmercury is water-soluble. B. Methylmercury is a neurotoxin. C. Methylmercury absorbs readily through the skin. D. Methylmercury accumulates in animal muscle and is biomagnified in the food chain.

D. Methylmercury accumulates in animal muscle and is biomagnified in the food chain.

The most abundant prokaryotic organism in the ocean is of the ________ genus. A. Prochlorococcus B. Puniceispirillum C. Roseobacter D. Pelagibacter

D. Pelagibacter

According to bacterial abundance studies done so far on soils, the ________ represent the most abundant phylum. A. Acidobacteria B. Firmicutes C. Actinobacteria D. Proteobacteria

D. Proteobacteria

Which of the following statements is NOT true regarding the evolution of antibiotic resistance in bacteria? A. Resistance can emerge due to mutations in chromosomal genes. B. Bacteria can acquire plasmids conferring resistance through horizontal gene transfer. C. Due to natural genetic variation within populations, resistant bacteria will be present--even in the absence of antibiotic. D. The exposure of bacteria to an antibiotic causes the bacteria to produce resistance genes.

D. The exposure of bacteria to an antibiotic causes the bacteria to produce resistance genes.

Collectively, metagenomic studies of the human microbiome have shown ALL BUT one of the following statements are true. A. Similarities in microbial diversity between individuals are more evident at higher bacterial taxonomic levels (such as phyla). B. Certain microbial genes appear to be linked to certain human body sites. C. Microbial diversity in the human microbiome is so great that no one microbial species is present in the greatest abundance in all individuals. D. There is no general pattern of similarity in the microbiomes of humans; they are unpredictable.

D. There is no general pattern of similarity in the microbiomes of humans; they are unpredictable.

Why are invasive procedures likely to increase the risk of nosocomial infections? A. These procedures are carried out by health care workers, who carry resistant microbes. B. Invasive procedures require long term hospital stays, thereby increasing the number of visitors seen by the patient. C. Invasive procedures must use antibiotics. D. These procedures allow microbes from the skin to enter the bloodstream of the patient.

D. These procedures allow microbes from the skin to enter the bloodstream of the patient.

What is the drawback of live attenuated vaccines? A. They do NOT provide a long-lasting secondary immune response. B. They are not effective in adults. C. They require more secondary reimmunizations than other vaccines. D. They can cause disease in some immunocompromised individuals.

D. They can cause disease in some immunocompromised individuals.

What is the role of fecal transplants in medicine? A. They remove the unhealthy microbes, allow the individual an opportunity to have recolonization by non-pathogens ingested with food. B. They can be used to treat infections caused by the overgrowth of Lactobacilli. C. They act as prebiotics to encourage healthy microbial growth. D. They can provide a healthy microbiota to help treat Clostridium difficle infections.

D. They can provide a healthy microbiota to help treat Clostridium difficle infections.

Why do obligate symbionts often contain lower G+C content when compared to free-living organisms? A. Ancestral symbionts had low GC content genomes by chance, and these low GC content genomes are passed onto their progeny. B. It is more difficult to replicate high G+C content genomes than to replicate low G+C content genomes. C. Organisms with a low G+C content organisms are at a selective disadvantage to those with a high G+C content when free-living. D. Two common spontaneous mutations change GC pairs into AT pairs and symbionts usually have fewer DNA repair mechanisms to fix these compared with free-living organisms.

D. Two common spontaneous mutations change GC pairs into AT pairs and symbionts usually have fewer DNA repair mechanisms to fix these compared with free-living organisms.

Why is it difficult to find good chemotherapeutic agents against viruses? A. There is no effective way to deliver the drug to the virus. B. Viruses are not cells, and therefore not sensitive to such compounds. C. Viruses infect both bacteria and human cells. D. Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.

D. Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.

The CD4 molecule is A. an HIV surface glycoprotein. B. found only on T-helper cells. C. an HIV surface glycoprotein that is found only on T-helper cells. D. a cell-surface protein that allows HIV to infect a cell.

D. a cell-surface protein that allows HIV to infect a cell.

The ocean has mitigated the impact of anthropogenic carbon dioxide production by A. absorbing 500 billion tons of atmospheric carbon dioxide. B. absorbing over 80% of the trapped heat energy. C. storing 600 billion tons of organic carbon. D. absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

D. absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

Symbionts can be acquired by an individual host organism horizontally (from the environment) or vertically (from a parent). In humans, there is evidence that infants are largely colonized by their parents' microbes, and family members living in the same household have microbiomes that are more similar than those of individuals living nearby. However, no two humans have identical microbiota, and certain factors, such as diet and antibiotics, can alter the microbiome. This indicates that humans may be colonized by __________. A. horizontal transmission B. neither vertical nor horizontal transmission C. vertical transmission D. both vertical and horizontal transmission

D. both vertical and horizontal transmission

A patient admitted to the hospital with muscle weakness and paralysis is put on a ventilator because of breathing difficulties. It is determined that the symptoms are the result of a bacterial exotoxin. How would she have obtained this? A. airborne bacteria B. a puncture wound C. contaminated water D. canned food

D. canned food

The element(s) that have proven most useful for stable isotope studies are A. nitrogen only. B. carbon only. C. sulfur only. D. carbon, sulfur, and sometimes nitrogen.

D. carbon, sulfur, and sometimes nitrogen.

Mutualisms may become prolonged, intimate and obligate symbioses through the process of __________. A. horizontal gene transfer B. endocytic colonization C. parasitism D. coevolution

D. coevolution

Which of the following techniques can link prokaryotic phylogeny and metabolic function? A. DAPI staining B. stable isotope probing only C. environmental genomics only D. environmental genomics and stable isotope probing

D. environmental genomics and stable isotope probing

Environmental damage due to acid mine drainage occurs only once ores containing pyrite (FeS2) are __________. A. mixed with other toxic metals like lead and cadmium B. increased in temperature to at least 50 degrees C. C. reduced from Fe3+ to Fe2+ oxidation states D. exposed to oxygen and water

D. exposed to oxygen and water

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________. A. cellular respiration B. metabolism C. glycolysis D. fermentation

D. fermentation

Metagenomics is a more sensitive analysis of community diversity than rRNA-based analyses because __________. A. rRNA genes are not found in all of the organisms present in the environment B. more clone libraries can be assembled C. the extraction of the DNA from the environmental samples is more efficient D. genes do not have to be amplified by PCR before being sequenced

D. genes do not have to be amplified by PCR before being sequenced

The influenza vaccine is an example of a(n) A. DNA vaccine. B. conjugated vaccine. C. toxoid vaccine. D. inactivated killed vaccine.

D. inactivated killed vaccine.

Which of the following is a cause of drug-specific resistance in disease-causing organisms? A. nosocomial infectionin B. appropriate hygiene C. poor immunity D. indiscriminate nonmedical use of antimicrobials

D. indiscriminate nonmedical use of antimicrobials

Initiation of biofilm formation in many organisms is at least in part regulated by c-di-GMP, which alters gene expression and enzyme activity leading to all of the following EXCEPT __________. A. initiation of extracellular polysaccharide production B. production of intercellular signaling molecules C. formation of cell surface attachment proteins D. initiation of flagella formation

D. initiation of flagella formation

Which of the following is most likely to cause disease? A. injection of 10^3 cells of a moderately virulent bacterial species into a mouse B. injection of 10^6 cells of a low virulent bacterial species into a mouse C. injection of 10^1 cells of a highly virulent bacterial species into a mouse D. injection of 10^5 cells of a highly virulent bacterial species into a mouse

D. injection of 10^5 cells of a highly virulent bacterial species into a mouse

Which of the following is a way to prevent attenuation and maintain virulence in a bacterium? A. laboratory subculture B. antibiotic therapy C. polymerase chain reaction (PCR) D. inoculating an animal with the bacterium

D. inoculating an animal with the bacterium

A farmer finds that his soybean plants do not look healthy. They appear stunted and the leaves are a yellowish color, indicating possible lack of nitrogen. To have a more successful crop next year, he should consider__________. A. increasing irrigation of his fields. B. fertilizing with ammonia fertilizer C. fertilizing his fields with iron. D. inoculating his fields with the appropriate cross-inoculation group of rhizobia

D. inoculating his fields with the appropriate cross-inoculation group of rhizobia

Carbon dioxide and methane are potent greenhouse gases, with methane having 20 times more warming potential in the atmosphere than CO2. As global warming progresses, there is the real possibility that increased temperatures on land and in the oceans will lead to a positive feedback effect leading to accelerated warming. From the carbon reservoirs listed below with their percentage of the total carbon on Earth, what would be the most dangerous potential source of C that could be released to potentiate further warming? A. rocks and sediments (99.5%) B. fossil fuels (0.006%) C. oceans and terrestrial biosphere (0.053%) D. methane hydrates (0.014%)

D. methane hydrates (0.014%)

It is thought that attenuation occurs especially in a laboratory setting because A. patients can be treated with drugs that induce attenuation. B. there is selection for more virulent strains in the laboratory. C. pathogens lose virulence with age and survive longer in laboratory cultures. D. nonvirulent or weakly virulent mutants grow faster in laboratory media when there is no selective advantage to virulence.

D. nonvirulent or weakly virulent mutants grow faster in laboratory media when there is no selective advantage to virulence.

Bacterial abundance (102 to 108) and generation times (days to centuries) vary by many orders of magnitude in the deep subsurface mainly due to __________. A. oxygen levels B. temperatures C. variations in water availability D. nutrient limitations

D. nutrient limitations

Gut microbiota is known to be linked with A. inflammatory bowel syndrome and Crohn's disease only, but not with ulcerative colitis. B. inflammatory bowel syndrome, but not with obesity. C. obesity, but not with inflammatory bowel syndrome. D. obesity and inflammatory bowel syndrome.

D. obesity and inflammatory bowel syndrome.

Nitrification and anammox both A. are aerobic processes, but nitrification produces NO3- and annamox produces N2 gas. B. occur in soils at neutral pH. C. create nitrogen gas, but nitrification is aerobic while anammox is anaerobic. D. oxidize ammonia, but nitrification uses O2 as an electron acceptor and anammox uses NO2-.

D. oxidize ammonia, but nitrification uses O2 as an electron acceptor and anammox uses NO2-.

Exotoxins are ________, but endotoxins are ________. A. lipopolysaccharide-lipoprotein complexes / proteins B. lipids / proteins C. carbohydrates / proteins D. proteins / lipopolysaccharide-lipoprotein complexes

D. proteins / lipopolysaccharide-lipoprotein complexes

Aerobic secondary treatment is usually best for ________ wastewater. A. industrial B. agricultural C. chemical D. residential

D. residential

Enrichment cultures are often effective for isolating bacteria from complex communities in natural samples because they __________. A. do not select for or against any bacteria; they help every organism to grow B. select for certain bacteria C. select against certain bacteria D. select both for and against certain bacteria

D. select both for and against certain bacteria

Which of the following is/are used to identify methicillin-resistant Staphylococcus aureus? A. selective media only B. differential media only C. PCR only D. selective media, differential media, and PCR can all be used

D. selective media, differential media, and PCR can all be used

An antimicrobial compound that targets a pathway or structure that is present in a pathogen but not in the host exhibits __________. A. antibiotic resistance B. complete toxicity C. narrow spectrum activity D. selective toxicity

D. selective toxicity

The overall purpose of DGGE is to A. separate genes that differ in length. B. measure the activity of cells that use DGGE as an energy source. C. detect cells that utilize a specific radiolabeled substrate. D. separate genes of the same length that have different sequences, resulting in different denaturation profiles.

D. separate genes of the same length that have different sequences, resulting in different denaturation profiles.

Which group of organisms is thought to be responsible for the corrosion of submerged metal structures and pipelines? A. acidophilic iron-oxidizers B. fermentative microorganisms C. hydrocarbon-degrading anaerobes D. sulfate reducers

D. sulfate reducers

In the soil, oxygen concentrations are highly variable even within a soil particle. The center of the particle may be anoxic even if the outer portions are oxygen rich. In this context, facultative anaerobes could be found A. in the middle regions of the particle. B. at the surface of the particle. C. in the center of the particle. D. throughout the particle.

D. throughout the particle.

For what purpose would a microbial ecologist use a microsensor? A. to determine the concentration of cells in small increments in a sediment or water column B. to determine the expression of a particular gene in a microbial community C. to quantify the uptake of a radioactive material D. to determine the concentration of O2, N2O, or other chemical species in small increments in a sediment or water column

D. to determine the concentration of O2, N2O, or other chemical species in small increments in a sediment or water column

Compared with pure cultures grown in the lab, microbes in nature usually experience a wider range of environmental conditions, more variation in conditions over time, and more contact with other organisms. Therefore, the same organism in nature will __________. A. typically grow faster than in pure culture B. carry out completely different metabolisms than in pure culture C. typically grow only on surfaces D. typically grow slower than in pure culture

D. typically grow slower than in pure culture

Resident staphylococci are commonly found in the ________ and these seldom cause disease. A. eyes B. kidneys C. lungs D. upper respiratory tract

D. upper respiratory tract

A higher number of methanogenic Archaea are found in the guts of mice and humans who are obese. It is thought that the methanogens help to foster obesity by__________. A. preventing the production of methane, thus enhancing nutrient absorption by the host B. creating a more oxidative environment, thus allowing respiration to occur. C. preventing further fermentation of substrates, thus allowing them to be used by the host D. using H2, thus allowing further fermentation of substrates

D. using H2, thus allowing further fermentation of substrates

Symbionts such as Rickettsia in whiteflies and Buchnera in aphids are transmitted ________ to ensure the safe transfer of the symbiont to the next host generation. A. vertically through the air B. horizontally through infected water C. horizontally through infected secondary hosts D. vertically to offspring

D. vertically to offspring

The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures? A. They are composed of a mixture of lipids and carbohydrates. B. They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume. C. They must block water and small molecules in order to regulate the exchange of matter and energy with their environment. D. They must permit information transfer between the cell's cytoplasm and the nucleus. E. They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.

E. They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.

T/F: Functional differences can be observed by using 16S rRNA gene phylogenetics of a microbial community.

False