test_3

Which of the pairs below are matched correctly for these clostridial pathogens involved in food poisoning? C. perfringens: produces enterotoxin C. botulinum: produces endotoxin C. perfringens: requires only a small number of cells to produce toxin C. botulinum: must grow in the body to produce toxin

C. perfringens: produces enterotoxin

Which of the following are NOT found in the gastrointestinal tract of healthy humans? a. Bacteroides b. Escherichia coli c. protists d. Clostridium

C. protists

One microenvironment of the skin is an area where glands produce an oily substance called a. lipid A b. mucus c. sebum d. fimbrae

C. sebum

Which antibiotic is overcome by beta-lactamases? Tetracycline Sulfonamide Penicillin Tetracycline, Penicillin, and Sulfonamide are all affected by beta-lactamase.

Penicillin

Why would an efflux pump for penicillin located on a bacterial cell membrane not be effective at providing resistance to the drug? The efflux pumps would not stop penicillin from blocking metabolic pathways. There are fewer efflux pumps on the cell membrane. The cell membrane is the target of penicillin. Penicillin disrupts the cell wall, which is located outside of the cell membrane.

Penicillin disrupts the cell wall, which is located outside of the cell membrane.

According to the animation, antibodies interact with which innate defenses? A. The complement system B. Phagocytosis, inflammation, and the complement system C. First-line defenses D. Phagocytosis E. Inflammation F. Phagocytosis and the complement system

Phagocytosis and the complement system

Which of the following antibiotics are properly matched with their target of action? macrolide-30S ribosomal subunit Platensimycin-lipid biosynthesis aminoglycoside-50S ribosomal subunit tetracycline-50S ribosomal subunit

Platensimycin-lipid biosynthesis

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

Practice more stringent aseptic techniques

One way to test if someone has immunity to a particular pathogen is to measure the antibody titer. What does it mean if someone has a positive antibody titer? Previous exposure to the pathogen (or through a vaccination) has caused B cells to produce memory B cells. When re-exposed to the pathogen, they rapidly produce antibodies against the antigen (resulting in a positive antibody titer). They must not have been exposed to the pathogen previously, meaning that they were able to rapidly produce antibodies. They must not have been exposed to the pathogen previously, meaning that they were not able to rapidly produce antibodies. Previous exposure to the pathogen has caused T cells to attack the pathogen, leading to a more rapid response by T cells upon repeat exposure.

Previous exposure to the pathogen (or through a vaccination) has caused B cells to produce memory B cells. When re-exposed to the pathogen, they rapidly produce antibodies against the antigen (resulting in a positive antibody titer).

The phylogenetic analysis of complex microbial communities often targets small subunit (SSU) ribosomal RNA genes. This is because rRNA is found in all organisms and __________.

is highly conserved over evolutionary time

The polymerase chain reaction, PCR, has revolutionized molecular genetics. Despite all of the advantages of PCR, it does have limitations. Which of the following is NOT a limitation of PCR? A) It is more error prone than most DNA replication. B) It requires very pure and high-quality DNA samples. C) It is necessary to know something about the sequence of the DNA sample prior to amplifying a specific region. D) PCR is so sensitive that contamination can easily occur.

B) It requires very pure and high-quality DNA samples.

Which domain of the A-B toxin binds to cell surface receptors on the host cell? A. A domain B. B domain C. A-B toxins do not bind to cell surfaces. D. Both the A and B domains have the ability to bind to cell surface receptors.

B domain

Restriction endonucleases are found in nature. They are extremely useful for genetic engineering. Why do organisms produce them? A) Organisms produce them as a way of allowing new genetic material to be inserted. B) Because they cut only at specific sequences in DNA, they are useful in cutting harmful DNA (such as viral DNA) without harming the organism that produces them (which can protect those sequences in its own DNA). C) They are part of the viral life cycle and help in the assembly of new viruses. D) They are involved in DNA replication in prokaryotes.

B) Because they cut only at specific sequences in DNA, they are useful in cutting harmful DNA (such as viral DNA) without harming the organism that produces them (which can protect those sequences in its own DNA).

An animal disease transmitted to humans by direct contact, inhalation of aerosols, or bites is called __________. epizootic a zoophyte enzootic a zoonosis

a zoonosis

Common probiotics include a. Bifidobacterium species. b. Escherichia coli. c. Corynebacterium species. d. Clostridium species.

a. Bifidobacterium species

The type of mycorrhizae found associated with forest trees like pines would be __________. none; not all plants form mycorrhizal associations ectomycorrhizae arbuscular mycorrhizae endomycorrhizae

ectomycorrhizae

The science of microbial ecology deals with

how the activity and biodiversity of microbial communities affect microbial interactions with each other and the environment.

Breaks down tight junctions and connective tissue

hyaluronidase

Which of the following enzymes breaks down the "glue" that holds cells together? Hyaluronidase Streptokinase Fibrinolysin Collagenase

hyaluronidase

The lowest number of pathogens or pathogen produced products that can be detected is a measure of __________. sensitivity specificity discrimination selectivity

sensitivity

Which of the following is an important virulence factor for dental caries? siderophores endotoxin polysaccharide adhesion pili

polysaccharide adhesion

Dissimilatory sulfide-oxidizers use a variety of unique ecological strategies in order to

position themselves at interfaces where sulfide and oxygen meet

H5N1 avian influenza is widely considered to be the most serious global pandemic threat today and is the target of much worldwide surveillance. The human H5N1 infections thus far have resulted in a mortality rate of almost 60%, underscoring the danger of this virus. Currently, the virus is not readily passed person to person, but reports that the virus may have recently entered (or re-entered) the swine population are of concern because of __________. possible antigenic drift humans typically come into more frequent contact with swine than with birds possible reassortment of the influenza genome with swine and human strains influenza more easily passing from pig to human than from human to human

possible reassortment of the influenza genome with swine and human strains

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

two subunits

True or False: Anthrax causes a localized infection when acquired through the mucous membranes of the lungs, but it causes a lethal, systemic infection when acquired through the skin. TRUE FALSE

False

What are leukocidins? A. Molecules that destroy the complement proteins B. Molecules that can degrade IgA C. Molecules that are capable of destroying phagocytes

Molecules that are capable of destroying phagocytes

Which of the following statements about the role of diet as a risk factor is TRUE? A. The number of organisms necessary to induce cholera is greatly increased when Vibrio cholerae is ingested in food. B. Increasing the amount of sucrose in your diet decreases the development of dental caries. C. Diets high in protein and calories alter the normal flora, increasing the host's susceptibility. D. The absence of a particular dietary substance may prevent disease by depriving a pathogen of critical nutrients.

The absence of a particular dietary substance may prevent disease by depriving a pathogen of critical nutrients.

The following compounds are all produced by intestinal microflora EXCEPT vitamin B12. vitamin K. flatus. vitamin C.

Vitamin C

Vibrio cholerae is a human pathogen that causes cholera. It has an unusual shape distinctive of its genus. Considering that it does not have one of the most common bacterial shapes, what is the shape of this species? a rigid spiral shape a spherical shape a curved rod a straight rod

a curved rod

The exotoxin that functions by destroying cell membranes is called __________. a cytolytic toxin an enterotoxin a superantigen toxin an A-B toxin

a cytolytic toxin

Anoxygenic phototrophs

can be either autotrophic or heterotrophic and may use a variety of electron donors for photosynthesis.

Gram-negative, rod-shaped bacteria that are facultative anaerobes, are non-spore formers, and ferment lactose to acid and gas are __________. fecal bacteria pathogens coliforms indicator organisms

coliforms

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

colon

Microbes that have a mutualistic relationship with their host are beneficial to their host, while __________.

commensals have little or no effect on the host

Microbes that have a mutualistic relationship with their host are beneficial to their host, while __________. pathogens kill the host parasites cause disease commensals have little or no effect on the host symbionts benefit at the expense of the host

commensals have little or no effect on the host

In DNA cloning, fragments of DNA need to be joined together (e.g., to add a fragment into a vector). What common enzyme is used for this process? helicases RNA polymerase DNA polymerase ligase

ligase

True or False: Helicobacter pylori is the MOST common single organism found in the stomach. TRUE FALSE

True

Only particles smaller than ___ μm in diameter reach the lungs. a. 40 b. 10 c. 30 d. 20

b. 10

All of the following areas of the human body should be microbially sterile EXCEPT __________. A. the lymphatic system B. the respiratory tract C. the bloodstream D. the nervous system

the respiratory tract

True or False: Hormones that are produced under stress conditions can inhibit normal immune responses and may play a role in stress-mediated disease. TRUE FALSE

True

Organisms that colonize skin __________. A. are never pathogenic B. are mostly gram-positive bacteria C. are always aerobes D. do not include eukaryotes

are mostly gram-positive bacteria

Nitrifying Thaumarchaeota outcompete nitrifying bacteria in many aquatic and terrestrial environments because Thaumarchaeota

are well-adapted to very low nutrient and electron donor concentrations.

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

attach and multiply

The decrease or loss of virulence of a pathogen is referred to as

attentuation

Which of the following is most likely to cause disease? injection of 101 cells of a highly virulent bacterial species into a mouse injection of 106 cells of a low virulent bacterial species into a mouse injection of 105 cells of a highly virulent bacterial species into a mouse injection of 103 cells of a moderately virulent bacterial species into a mouse

injection of 105 cells of a highly virulent bacterial species into a mouse

Adherence factors include ALL of the following EXCEPT A. capsule. B. fimbriae. C. flagella. D. lipopolysaccharide.

lipopolysaccharide

The most important rickettsial diseases in humans include __________. Q fever Lyme disease typhus fever West Nile fever

typhus fever

Benefits of studying the human microbiome

-It may allow for the development of personalized medical treatments. -It may allow for more finely targeted probiotics. -It may allow for increased recognition of disease biomarkers.

Bacterial abundance (10^2 to 10^8) and generation times (days to centuries) vary by many orders of magnitude in the deep subsurface mainly due to __________. temperatures variations in water availability nutrient limitations oxygen levels

nutrient limitations

A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a(n) A. superantigen. B. enterotoxin. C. membrane disrupting toxin. D. neurotoxin.

neurotoxin

In the search for new antimicrobial drugs, to minimize resistance developing scientists should focus on __________. combinations of current antimicrobial compounds new targets of action found only in bacteria new targets of action found only in eukaryotes modifications of current antimicrobial compounds

new targets of action found only in bacteria

In Bacteria, the MOST common oxidized form of nitrogen is ________ and of sulfur is ________.

nitrate/sulfate

Which part of the nitrogen cycle increases the chances for nitrogen to get leached from soils into aquatic ecosystems?

nitrification (ammonium to nitrate)

Some lichen symbionts can survive independently on bare rocks in the absence of any external source of organic matter due to the ability of the phototrophic partner to fix CO2 from the air, and __________. A)acquisition of water by the algal partner B)chemolithotrophy by the bacterial partner. C)nitrogen fixation by the cyanobacterial partner D)production of acids by bacterial fermenters to release minerals from the rock

nitrogen fixation by the cyanobacterial partner

Greenhouse gases

such as CO2, CH4, and N2O trap infrared radiation and heat the Earth.

Which of the following pairs of microorganisms are NOT likely to form close associations or consortia?

nitrogen-fixing cyanobacteria and dissimilative sulfate-reducers

Identification of a pathogen in a patient can be done without having to culture the pathogen using __________. none of the listed responses are correct PCR testing if a host specific genetic sequence is known PCR testing if a pathogen specific genetic sequence is not known PCR testing if growing the pathogen in the lab is common

none of the listed responses are correct

Microorganisms usually found associated with human body tissue

normal microbial flora

Healthcare-associated infections are also called A. opportunistic pathogenic infections. B. attenuated infections. C. virulent infections. D. nosocomial infections.

nosocomial infections

Which of the following is correct pertaining to cytolytic toxins? A. are extracellular proteins. B. cause cell lysis and death. C. damage host cytoplasmic membrane. D. normally form part of the cell wall. E. can lead to pus production.

1. are extracellular proteins 2. cause cell lysis and death 3. damage host cytoplasmic membrane 4. can lead to pus production

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. 2, 2, 20 5, 5, 20 2, 2, 5 5, 2, 5

2, 2, 5

The damaged areas of teeth by organic acids produced by dental plaque are called a. calcified plaque. b. dental caries. c. degenerative plaque. d. pediodontal disease.

B. dental caries

Which of the following is true about hybridization? A) RNA strands must be entirely complementary in order to hybridize, although DNA strands can hybridize with DNA or RNA even if there are some differences in the base sequences. B) DNA strands must be completely complementary in order to hybridize, although RNA strands can hybridize with DNA or RNA even if there are some differences in the base sequences. C) DNA strands that differ in a few bases may still be able to hybridize D) When used as probes, DNA can hybridize only with DNA, and RNA can hybridize only with RNA.

C) DNA strands that differ in a few bases may still be able to hybridize

In mycorrhizal mutualisms between plants roots and fungi, A)the fungus infects the plant roots, stimulating plant growth through myc factors that act as growth hormones in the plant. B)the plant supplies water to the fungus and the fungus supplies essential amino acids to the plant. C)the plant supplies carbohydrates to the fungus and the fungus supplies phosphorus and nitrogen to the plant. D)the plant protects the fungus from predation and the fungus supplies carbohydrates to the plant.

C)the plant supplies carbohydrates to the fungus and the fungus supplies phosphorus and nitrogen to the plant.

Which of these microorganisms is most likely to be found in the human stomach? a. Roseobacter denitrifcans b. Streptococcus mutans c. Heliobacter pylori d. Streptococcus sobrinus

C. Heliobacter pylori

How can capsules enable bacteria to evade the immune system? A. A capsule is a superantigen that distracts the immune system. B. Capsules block the complement biding sites on the surface of the pathogen. C. Capsules can bind up IgA, rendering it inactive.

Capsules block the complement biding sites on the surface of the pathogen.

Based upon microbiome projects, the dominant microbial species on the skin is a. Streptoccocus species. b. Staphyloccocus species. c. Corynebacterium species. d. Propionibacterium species.

D. Propionibacterium species.

Which of the following environmental and host factors influence the composition of the resident micrbiota on the skin? a. weather b. age c. personal hygiene d. age, personal hygiene, and weather

D. age, personal hygiene, and weather

Which of the following is NOT a function of the human gut microbiome? a. production of essential amino acids and vitamins. b. maturation of the gastrointestinal tract. c. production of volatile fatty acids from polysaccharides. d. iron and trace metal absorption.

D. iron and trace metal absorption

TRUE OR FALSE: All microorganisms that live in the human body are harmful.

False

Which bacteria involved in food infections produce toxins to cause host damage? Listeria and Escherichia coli Listeria and Salmonella Campylobacter and Escherichia coli Escherichia coli and Salmonella

Escherichia coli and Salmonella

Ferrous iron (Fe2+) oxidation generally occurs in environments with

High H+ concentrations

Which of the following enzymes breaks down the "glue" that holds cells together? A. Hyaluronidase B. Streptokinase C. Fibrinolysin D. Collagenase

Hyaluronidase

Which of the following is the dominate genera of skin microflora? Bacteriodes Actinobacteria Proteobacteria Firmicutes

actinobacteria

Nitrogen fixation results in the

addition of biologically available N to an ecosystem.

Following exposure to a pathogen, events leading to disease—in the correct order—are A. adherence, virulence, invasiveness B. adherence, invasion, infection, toxicity C. invasion, adherence, virulence D. invasion, adherence, toxicity, infection

adherence, invasion, infection, toxicity

Which of the following environmental and host factors influence the composition of resident microflora on the skin? personal hygiene age weather age, personal hygiene, and weather

age, personal hygiene, and weather

Which bacterium contains a large Ti plasmid and causes crown gall disease in plants? Agrobacterium rhizogenes Aliivibrio fischeri Butyrivibrio fibrisolvens Agrobacterium tumefaciens

agrobacterium tumefaciens

Lyme disease and syphilis are similar in that they __________. are both chronic infections that involve the nervous system are both contracted by person-to-person contact are both caused by spirochetes and are chronic infections that involve the nervous systems are both caused by spirochetes

are both caused by spirochetes and are chronic infections that involve the nervous systems

Microbial mats differ from biofilms in that they __________.

are currently found only in extreme habitats

Microbial mats differ from biofilms in that they __________. A-are found only attached to surfaces B-contain more than one species of microorganism in the community C-are currently found only in extreme habitats D-have different environmental conditions at various depths within the community

are currently found only in extreme habitats

All students that ate in the school dining hall on Monday developed stomach cramps and diarrhea. The student clinic was overwhelmed with patients. However, by Thursday the number of patients seen in the clinic was back to normal. This could have been caused by a __________. host-to-host epidemic common-source epidemic infectious disease vector-borne disease

common-source epidemic

In 2011, the CDC reported a 28-state outbreak of Listeria monocytogenes that killed 33 people in the United States. The victims were found to have eaten portions of whole cantaloupe melons originating from a single farm in Colorado. The FDA traced the source of bacterial contamination to a piece of used equipment that had been recently purchased to wash the melons, nearby puddles of water, and a truck that hauled spoiled melons to a field to be fed to cattle. This would be an example of __________. zoonotic reservoir water-borne transmission person-to-person transmission common-source transmission

common-source transmission

The fate of carbon fixed by primary producers such as phytoplankton occurs by all EXCEPT: A) Consumption by zooplankton grazers B) Consumption by other phytoplankton C) Consumption by heterotrophic bacteria D) Processed by viruses

consumption by other phytoplankton

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

continuous culture

These pathogens show little difference in the number of cells required to kill 100% of the population as compared to 50% of the population

highly virulent pathogens

Two major environmental extremes of the deep sea are high ________ and low ________.

pressure/ nutrient levels

Under what scenario would an oligotroph outcompete a copiotroph in the soil?

under low nutrient conditions

Measure of pathogenicity

virulence

Microbial parasites

pathogen

Leads to systemic shock

toxic shock toxin

Epidemiology is defined as the study of how a disease is transmitted. where and when a disease occurs, and how it is transmitted. where a disease occurs. when a disease occurs.

where and when a disease occurs, and how it is transmitted.

Of the arthropod-borne diseases, there is a vaccine to prevent __________. West Nile fever yellow fever Lyme disease dengue fever

yellow fever

TRUE OR FALSE: The male reproductive tract is generally sterile except for the distal portion of the urethra.

TRUE

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

2,2,5

According to the animation, surgical infections account for what percentage of nosocomial infections? 15% 11% 8% 40% 20%

20%

Place the steps of root nodule formation in the correct order.1. bacteroids 2. Nod factor secretion 3. invasion 4. recognition of partners 5. mature nodule

4 2 3 1 5

Which of the following explains why treatment of symptomatic tetanus requires an antitoxin and an antibiotic? It is always better to use multiple treatments to elicit a stronger response. Because the toxin is within the cell wall of the bacteria, it can only be eliminated by killing the bacteria. Because C. tetani bacteria excrete tetanus toxin, it is important to neutralize the toxin while also killing the bacteria that are producing more. The tetanus toxin binds irreversibly, causing damage to axons. The only way to heal the axons is with an antitoxin.

Because C. tetani bacteria excrete tetanus toxin, it is important to neutralize the toxin while also killing the bacteria that are producing more.

What is TRUE about stomach microbiota? a. the alkaline environment supports a wide variety of species. b. few microbes can survive because it is so acidic. c. despite the acidic of the stomach, diverse phylotypes of resident microbes thrive in the stomach. d. there is rich diversity of transient microbes, but few resident microbes.

C. Despite the acidic of the stomach, diverse phylotypes of resident microbes thrive in the stomach.

Extensive microbial growth in a thick bacterial layer on the teeth is called a. dental biofilm. b. periodontitis. c. dental plaque. d. dental caries.

C. dental plaque

Normal microbiota helps to ________ colonization of pathogenic organisms. a. accelerate b. maintain c. promote d. prevent

D. prevent

The vagina of an adult female is a. highly alkaline. b. highly acidic. c. weakly alkaline. d. weakly acidic.

D. weakly acidic

Endotoxins are also known as A. Lipid A. B. cytokines. C. interleukin-1. D. prostaglandins.

Lipid A

Which of the following are susceptible to HIV infection? A. all primates B. all animals that have the CXCR4 and CCR5 proteins C. all animals that lack the CXCR4 and CCR5 proteins D. only humans

all animals that have the CXCR4 and CCR5 proteins

A hard-core, steak-loving athlete has fallen for a vegan. In order to maintain harmony in their relationship, the athlete has willingly given up meat and all animal products in their diet. They are now on a strictly plant-based diet. What would you expect to see? A. a change in the gut microbiota B. loss of microbiota that secrete proteases C. an increase in microbes that secreate cellulases D. all of the above

all of the above

Which of the following healthcare procedures may unintentionally introduce microorganisms into the patient? A. catheterization B. surgery C. spinal puncture D. all of the above

all of the above

The distribution of disease can change very quickly. An increase in emerging diseases can be attributed to __________. more people being immunized more people moving away from cities unchanging climate an increase in international travel

an increase in international travel

Ouch, you have a gum infection. After flossing you notice blood on the floss and tootbrush. Some bacteria have now entered your blood. This would be called:

bacteremia

R-plasmids are most likely acquired via Check all that apply. transformation. translation. transduction. bacterial conjugation.

bacterial conjugation

All of the following are typical gram-positive organisms found on the skin EXCEPT __________. Bacteroides Staphylococcus Corynebacterium Propionibacterium

bacteroides

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

biofilms are composed of only one species at a time

A person who tests positive for the human immunodeficiency virus but shows no symptoms of AIDS would be termed a __________. vector carrier reservoir vehicle

carrier

How is a bacteroid distinguished from a bacterial cell? A)biochemical tests B)16S rRNA gene sequencing C)cell morphology D)16S rRNA gene sequencing, biochemical tests, and cell morphology

cell morphology

Leads to an overproduction of cAMP and the secretion of chloride and bicarbonate ions from the small intestinal cells into the intestinal lumen

cholera toxin

Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells. coagulase amylase lipase collagenase

coagulase

Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells. A. collagenase B. coagulase C. lipase D. amylase

coagulase

From the aquatic systems below, where are heterotrophic Bacteria the MOST abundant?

coastal waters

Mutualisms may become prolonged, intimate and obligate symbioses through the process of __________.

coevolution

An exotoxin that has the ability to kill or damage host cells is referred to as a(n) A. A-B toxin. B. cytotoxin. C. neurotoxin. D. enterotoxin. E. superantigen.

cytotoxin

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

transduction

The most heavily colonized human organ by bacteria is the _______, containing 10^11 10^12 bacterial cells per gram. a. mouth b. large intestine c. small intestine d. skin

B. large intestine

Following antibiotic therapy, patients are often administered ______ to facilitate recolonization of normal microbiota in the intestines. a. iron. b. probiotics. c. antivirals. d. fluoride.

B. probiotics

Which cells directly attack abnormal cells in the body? A. Helper T cells B. B cells C. Cytotoxic T cells D. Phagocytes

Cytotoxic T cells

Quinolones and fluoroquinolones act against what bacterial target? Metabolic pathways unique to bacteria Cell membranes Bacterial ribosomes Cell walls DNA gyrase

DNA gyrase

TRUE OR FALSE: A healthy vaginal microbiome is dominated by Candida.

FALSE

TRUE OR FALSE: Normal microbiota is usually found in the blood, lymph, and nervous systems of the body.

FALSE

Which of the following would happen if you accidentally drink water contaminated with Clostridium tetani? A. The pathogen would be killed by the acidity of the stomach. B. The pathogen would outcompete the well-developed intestinal flora. C. The pathogen would grow and produce tetanus toxin. D. Death from tetanus would occur.

The pathogen would be killed by the acidity of the stomach.

If the biochemical oxygen demand (BOD) of a lake is very high, how will that affect the aquatic life in the lake?

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

As you move through the digestive tract the amount of available oxygen _____________ while the pH _____________. A. increases / increases B. decreases / decreases C. increases / decreases D. decreases / increases

decreases / increases

In which of the following environments would you expect to find a high number of iron-reducing bacteria?

deep subsurface

Bacteria will become part of a biofilm because __________.

it allows them to remain in a favorable niche

Dissolves fibrin clots

strepokinase

Some nitrifying prokaryotes carry out metabolic cooperation by a process known as

syntrophy

Most nitrogen-fixing bacteria symbiotically associated with plants are called

rhizobia

Metagenomics involves the analysis of a microbial community by __________.

sampling and sequencing all of the genes in an environment

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

viruses require host cells to replicate themselves

Which of the following is NOT produced by microorganisms in the gut of humans? A. vitamin B12 B. vitamin K C. vitamin C D. CO2

vitamin C

A patient is brought to the hospital with severe gastrointestinal distress, including cramps, dehydration and diarrhea. Which of the following symptoms would indicate that the pathogen is Vibrio cholerae? occasional diarrhea but no blood in the stool frequent vomiting voluminous watery diarrhea bloody, foul smelling diarrhea

voluminous watery diarrhea

The vagina of adult female is weakly acidic. weakly alkaline. highly acidic. highly alkaline.

weakly acidic

Rickettsia are obligate intracellular parasites that are transmitted by arthropods. In which of the following places would you most likely find the parasites living in the host organism during the course of infection? within the blood plasma on the surface of heart cells on the outer surface of the skin within macrophages

within macrophages

Damage or injury to the host that impairs host function

disease

The ability of a parasite to inflict damage on the host

pathogenicity

Which of the following is correct pertaining to endotoxins? A. Made up of the lipid A portion of the LPS complex. B. Produced by both Gram positive and Gram negative cells. C. Considered moderately toxic and requires a large amount to be fatal. D. Often encoded on bacterial plasmids. E. Can lead to fever, diarrhea, and vomiting.

1. Made up of the lipid A portion of the LPS complex 2. Considered moderately toxic and requires a large amount to be fatal 3. Can lead to fever, diarrhea, and vomiting

Which of the following would be correct about our microbiota? A. The lower respiratory tract typically lacks microflora in healthy individuals. B. Microflora typically are found on all surfaces of the respiratory tract. C. The bladder is only sterile in males. D. Women are more prone to urinary tract infections. E. Streptococci and Staphylococci are the most common causes of urinary tract infections.

1. The lower respiratory tract typically lacks microflora in healthy individuals 2. Women are more prone to urinary tract infections

As an epidemiologist, Dr. Thompson is interested in determining the frequency with which a specified event occurs within a particular population at a certain instant or during a particular period. This measure is known as a rate. In epidemiologic practice, an attack rate is the most commonly used method of determining the extent or frequency with which a disease is experienced by a population of individuals. In this instance, Dr. Thompson is interested in knowing what percentage of the individuals who attended the July 4 celebration became ill. What is the attack rate of food poisoning among the group who attended the July 4 celebration? 40/65(100)= 61.5% 65/105(100)= 61.9% 40/150(100)= 26.6% 105/150(100)= 70.0%

105/150(100)= 70.0%

Which of the following correctly orders the successful application of epidemiology to control the emergence of SARS? 1. Sales restriction of civets and other wild food sources. 2. Containment and infection-control of virus in healthcare settings 3. Source of SARS traced to bats and civets. 4. Travel restricted to and from endemic areas. 5. Initial outbreak of SARS identified. 5, 4, 1, 3, 2 4, 5, 3, 2, 1 5, 3, 2, 4, 1 3, 5, 4, 2, 1

5, 3, 2, 4, 1

Electrophoresis can be used to separate molecules by size, shape, and charge. When DNA samples are run in an electrophoresis gel, the different bands produced generally represent fragments of different sizes. Why is the size of the fragment the most critical factor in determining how far it migrates on a gel when DNA fragments are compared? A) DNA moves toward a positive charge due to the negative charge on its phosphate groups. The charge is consistent because all DNA nucleotides have a single phosphate group rather than having more diverse patterns of charges. Because the charge is relatively consistent, size is the most important factor determining how far fragments move. B) A special type of gel is used for DNA electrophoresis to minimize the effects of charge. C) The charge on DNA is so small that it has a minimal effect on movement in the gel. D) The shape of the DNA fragments has an even greater effect on movement than size or charge, so charge is relatively unimportant.

A) DNA moves toward a positive charge due to the negative charge on its phosphate groups. The charge is consistent because all DNA nucleotides have a single phosphate group rather than having more diverse patterns of charges. Because the charge is relatively consistent, size is the most important factor determining how far fragments move.

What might be a reason that a researcher would decide to use Northern blotting instead of Southern blotting? A) to determine the extent to which a gene is being transcribed in a particular tissue B) to compare the proteins present in different cells C) to determine whether gene amplification was used to increase transcription of a gene in a particular organism D) to determine the extent to which a gene is being translated in a particular tissue

A) to determine the extent to which a gene is being transcribed in a particular tissue

Which of the following is known to be TRUE about dog owners and their dogs? a. skin microbes are more common between dog owners and their own dogs than between dog owners and other dogs. b. dog owners have more skin microbes than those who don't own dogs. c. dog owners have fewer skin microbes than those who don't own dogs. d. skin microbes are similar between dog owners and dogs in general, with no difference in similarity when dogs and their owners are compared with other human-dog pairs.

A. Skin microbes are more common between dog owners and their own dogs than between dog owners and other dogs.

Clostridium difficle infections most often occur a. following antibiotic treatment. b. following a fecal transplant. c. following a dietary change. d. following the use of a new probiotic.

A. following antibiotic treatment.

Which type of mutation would have a more lethal effect on the bacterium? A mutation preventing production of an exotoxin or a mutation prevention production of the endotoxin? Explain.

An endotoxin because the complex phospholipid-polysaccharide macromolecules form an integral part of the outer membrane. They need the outer membrane for their survival.

Although cholera can be treated with antibiotics, data suggest that antibiotic treatment alone is NOT the most effective therapy. Which of the following statements describes the most likely reason for supplementing antibiotic therapy? The production of cholera toxin helps V. cholerae resist antibiotic treatment. Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae. Because V. cholerae is a gram-negative organism, it is not very effectively treated with antibiotics. As with V. cholerae, the acidic environment of the stomach can have a negative impact on antibiotic activity.

Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae.

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

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

Explain why women of childbearing age often develop a vaginal yeast infection when they are on antibiotics

Antibiotics can destroy "good bacteria" in your vagina. This bacteria helps to keep the body's natural yeast population in check. When the good bacteria gets destroyed, yeast can multiply and potentially cause a yeast infection. This lowers the amount of lactobacilli that help keep the pH of the vagina slightly acid. Yeast can take advantage of the rising pH and increase their growth leading to yeast infection.

Why are antibiotics often ineffective in treating food poisoning (food intoxication)? Oral antibiotics are degraded by stomach acid and, therefore, do not work well in the digestive tract. Pathogens in food pass through the digestive tract too rapidly to be targeted by antibiotics. Food poisoning is caused by viruses, which are not targeted by antibiotics. Antibiotics target bacteria; they do not damage toxins.

Antibiotics target bacteria; they do not damage toxins.

Under what conditions could a member of the gut microbiota become a pathogen?

Any situation that reduces the normal gut flora (giving an organism a chance to take over and cause illness) or allow a member of the normal gut flora to access other body sites could allow it to cause disease. Ruptured appendix Antibiotics Salmonella

In gene cloning, a fragment of interest is placed into an appropriate vector and then replicates within the host cell. Which of the following is NOT an advantage to using a plasmid inserted into an E. coli bacterium for cloning? A0 E. coli has been well studied and its genetics are very well known. B) Plasmids can hold large inserts of DNA. C) Plasmids can be easily inserted into E. coli and it maintains plasmids quite well. D) E. coli is susceptible to a variety of antibiotics.

B) Plasmids can hold large inserts of DNA.

Why is a special polymerase, such as Taq polymerase, required for PCR? A) Taq polymerase can add DNA or RNA, allowing amplification of DNA or RNA. B) Taq polymerase is produced by an extremophile prokaryote and is able to work at relatively high temperatures. C) Taq polymerase adds bases more rapidly than other polymerases, allowing very rapid amplification. D) Taq polymerase can add complementary bases in an extremely accurate way, resulting in a very low error rate.

B) Taq polymerase is produced by an extremophile prokaryote and is able to work at relatively high temperatures.

When a DNA gel is run, a standard sample with fragments of known size is often run in one well. Why is it important to use a standard sample? A) The standard sample helps to make the other samples more visible. B) When an electrophoresis gel is run, small differences in the environment (e.g., the gel composition and current) can influence how far the fragments travel. Having a standard sample allows one to compare the test fragments with fragments of known size that have been run under the same conditions. C) The standard sample is used to make sure that the electrical current is working properly. D) The standard sample is used to demonstrate that the apparatus is working properly; it is a control.

B) When an electrophoresis gel is run, small differences in the environment (e.g., the gel composition and current) can influence how far the fragments travel. Having a standard sample allows one to compare the test fragments with fragments of known size that have been run under the same conditions.

Many restriction enzymes produce sticky ends, which are very useful for genetic engineering. What makes the ends sticky? A) After the restriction enzyme cuts the DNA strands, additional steps are used to add nucleotides to the ends of each strand. These newly added nucleotides can form hydrogen bonds to join with other strands. B) When the restriction enzyme cuts, it cuts the two strands of a double-stranded DNA molecule unevenly. This produces overhanging DNA nucleotides on each fragment. These overhanging fragments are complementary to each other or to other fragments produced using the same restriction enzyme. C) When the restriction enzyme cuts, it separates the two strands of DNA in a similar manner to the way that the strands separate in a replication bubble. Whenever the two strands of a DNA molecule are pulled apart, complementary bases are separated that can easily come back together again. D) Restriction enzymes cut the phosphodiester backbone of the DNA molecule. The broken bonds can easily re-form, rejoining the separated fragments.

B) When the restriction enzyme cuts, it cuts the two strands of a double-stranded DNA molecule unevenly. This produces overhanging DNA nucleotides on each fragment. These overhanging fragments are complementary to each other or to other fragments produced using the same restriction enzyme.

What benefit does the fungal partner get from the lichen relationship? A)The alga anchors the fungus to the substrate. B)The alga provides organic compounds for food to the fungus. C)The alga produces lichen acids that help provide inorganic nutrients from the substrate. D)The alga facilitates water uptake.

B)The alga provides organic compounds for food to the fungus

Bacillus anthracis is an endospore-forming bacterium. Which of the following is most likely? B. anthracis uses spores to reproduce, which develop into new offspring capable of causing anthrax. B. anthracis spores require a moist environment in order to stay dormant for an extended time. These spores will germinate and be capable of causing anthrax when they dry out. B. anthracis spores can remain dormant for hundreds of years without needing nutrients, remaining capable of causing anthrax when they germinate. B. anthracis spores can be killed by boiling water or ultraviolet light, so these can be used to prevent anthrax.

B. anthracis spores can remain dormant for hundreds of years without needing nutrients, remaining capable of causing anthrax when they germinate.

The following compounds are all produced by intestinal microbiota EXCEPT a. vitamin K. b. vitamin C. c. vitamin B12. d. thymine

B. vitamin C

What type of nosocomial infection is likely to arise from intravenous catheterizations? Bacteremia Urinary tract Lower respiratory Surgical Cutaneous

Bacteremia

Penicillin and other β-lactam antibiotics inhibit cell-wall synthesis. What makes them effective at killing bacterial cells? Bacteria are generally hypertonic relative to their environment, so they desiccate when their cell wall is weakened by the action of these antibiotics. Bacteria are generally hypotonic relative to their environment, so they burst when their cell wall is weakened by the action of these antibiotics. Bacteria are generally hypertonic relative to their environment, so they burst when their cell wall is weakened by the action of these antibiotics. Bacteria may burst or desiccate when their cell wall is weakened by the action of these antibiotics.

Bacteria are generally hypertonic relative to their environment, so they burst when their cell wall is weakened by the action of these antibiotics.

All of the following are Gram-positive genera typically found on the skin EXCEPT __________. Propionibacterium Bacteroides Staphylococcus Corynebacterium

Bacteroides

Which of the following is TRUE about research on the human microbiome? a. culture-dependent techniques fully elucidated its microbial diversity. b. cultivation was unimportant in studying its microbial diversity. c. advanced nucleic acid sequencing techniques were needed before a good understanding of its microbial abundance and diversity could be developed. d. none of the answers are correct.

C. advanced nucleic acid sequencing techniques were needed before a good understanding of its microbial abundance and diversity could be developed.

The pouch at the beginning of the large intestine is called the a. cardia b. ileum c. cecum d. colon

C. cecum

Decomposition of organic carbon ultimately results in the formation of __________.

CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

How can capsules enable bacteria to evade the immune system? Capsules block the complement biding sites on the surface of the pathogen. Capsules can bind up IgA, rendering it inactive. A capsule is a superantigen that distracts the immune system.

Capsules block the complement biding sites on the surface of the pathogen.

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

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

Everyone, but particularly individuals who are farmers, gardeners, foresters, or others who spend significant time outdoors, are urged to adhere to a tetanus booster vaccinations schedule, receiving a booster if planning to travel and cannot remember when his or her last one. Why? Clostridium tetani typically causes infection when a wound is contaminated with soil, it's natural habitat. Accidental ingestion of Clostridium tetani toxin would lead to rapid onset of symptoms and an inability to call for help. Clostridium tetani typically causes infection when it produces quick-acting exotoxins that affect the nervous system. Quick treatment would not be available to victims who succumb far from help. There are no antibiotics available to treat this bacterial infection.

Clostridium tetani typically causes infection when a wound is contaminated with soil, it's natural habitat.

What is the role of fecal transplants in medicine? a. they act as prebiotics to encourage healthy microbial growth. b. they remove the unhealthy microbes, allow the individual an opportunity to have recolonization by non-pathogens ingested with food. c. they can used to treat infections cause by the overgrowth of Lactobacilli. 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.

When an individual has severe diarrhea, as can occur with cholera, rehydration solution with glucose, salt, sodium bicarbonate, and potassium chloride can be administered. Why is it important to use a solution like this rather than simply giving the individual water? Hints The salt helps to reduce bacterial contamination and spoilage of the rehydration fluids. This type of solution is hypertonic to human body fluids and, therefore, causes water to flow into cells. It is not necessary; water would be equally effective. Patients suffering from diarrhea loose mainly water through their stools, and dehydration is dangerous. Diarrhea causes the loss of electrolytes, not just fluids. It is important to replace the electrolytes as well as the water.

Diarrhea causes the loss of electrolytes, not just fluids. It is important to replace the electrolytes as well as the water.

Clostridium tetani is an obligate anaerobe that can cause tetanus. When it enters the human body, it can produce tetanus toxin. Considering that C. tetani is an obligate anaerobe, which of the following explains how it can survive and cause disease in the human body? Especially in deep wounds, C. tetani can sometimes survive in areas with damaged tissue that have become anoxic because of poor-to-no blood flow. It doesn't survive but instead simply releases toxin as it dies. C. tetani can't access atmospheric oxygen, so it can grow as long as it stays on the surface of the skin rather than in well-oxygenated deeper tissues. C. tetani can only survive when other bacteria are available to consume oxygen and to keep oxygen levels low.

Especially in deep wounds, C. tetani can sometimes survive in areas with damaged tissue that have become anoxic because of poor-to-no blood flow.

An adult usually has an extensive system of normal flora associated with our ______________ and this prevents botulism bacteria from attaching and releasing their _______________ causing toxin. A. Digestive tract/ spastic paralysis B. Respiratory tract/flaccid paralysis C. Urogenital tract/spastic paralysis D. Digestive tract/flaccid paralysis E. Skin/spastic paralysis

Digestive tract/flaccid paralysis

Why will the microbiota in the vagina of a woman of reproductive age differ from that of the same woman before puberty and after menopause? During the reproductive years, bacterial community in the vagina changes every month due to menstruation. Before puberty and after menopause, the vagina is colonized primarily by Lactobacillus acidophilus, which creates an acidic environment through fermentation. During the reproductive years, bacteria are introduced to the vagina during intercourse and colonize the mucosa. Before puberty and after menopause the vagina is sterile. During the reproductive years, the vagina contains significant amounts of glycogen that is fermented by Lactobacillus acidophilus to produce lactic acid, creating an acidic environment. Glycogen is absent before puberty and after menopause. During the reproductive years, the vagina is colonized only by Lactobacillus acidophilus, which produces lactic acid by fermentation, creating an acidic environment. Before puberty and after menopause the vagina is alkaline.

During the reproductive years, the vagina contains significant amounts of glycogen that is fermented by Lactobacillus acidophilus to produce lactic acid, creating an acidic environment. Glycogen is absent before puberty and after menopause.

Place the stages of maturation of the light organ in Euprymna scolopes in the correct order. A. migration to light organ B. monoculture of bacteria established C. reproduction of bacteriaD. mature light organE. mucus secretion by squid E, A, C, B, D E, C, A, B, D E, B, C, A, D E, B, A, C, D

E, B, A, C, D

Membrane transport proteins are required for which mode(s) of antibiotic resistance? Efflux pumps Modification of a porins Modification of a metabolic enzyme Beta-lactamases Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins.

Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins.

Which of the following is FALSE about the influence of age on susceptibility to infection? A. Infectious diseases are more common in the very old and very young. B. Enlargement of the prostate in men over 50 leads to suppression of the immune response. C. Before the development of adult flora, pathogens have a greater opportunity to become established and cause disease. D. Anatomical changes associated with age may encourage infection.

Enlargement of the prostate in men over 50 leads to suppression of the immune response

TRUE OR FALSE: Probiotics do not contain living microbes.

FALSE

True or False: Endotoxins are the secreted products of living cells, whereas exotoxins are cell bound and released in large amounts ONLY when the cells lyse. TRUE FALSE

False

Which of the following would be the first sign of an infection that resulted in the release of endotoxin? A. Weakness B. Nausea C. Pain D. Fever

Fever

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

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

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

Humans and other animal hosts lack peptidoglycan cell walls.

West Nile Virus is an arbovirus that can be transmitted by birds because they develop viremia when infected. In contrast, infected humans cannot spread the disease because they do not develop viremia. Why is viremia associated with the ability to transmit the disease? Direct contact with blood is required for infection. If there are no viral particles in the blood, then infection can't occur using this mechanism. Because white blood cells are found in the blood, any virus in the blood would be attacked by the immune system. With no viral particles available for the immune system to attack, the virus cannot be spread. The virus is only found within red blood cells if there is no viremia, so it cannot be spread by mosquitoes that do not consume those cells. If there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection.

If there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection.

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? Microbes respond to the presence of antibiotics by deliberately developing resistance mechanisms. Exposure to too much of an antibiotic causes resistance. Antibiotics are mutagenic. They cause mutations, like other mutagenic chemicals. 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.

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.

From the preliminary analysis, it would appear that individuals who consumed barbecue with Bubba-Qs sauce had the highest attack rate, followed by the dry-rubbed barbecue. Some of the individuals who said they ate the barbecue with the sauce did not become ill. Which one of the following is the most likely explanation for such an occurrence? Not everyone who was questioned may accurately remember which foods they consumed. Individuals who did not become ill are genetically less susceptible to the food poisoning agent. Some individuals may have immunity to the illness because they have been previously exposed. Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.

Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.

________ is the growth of microorganisms NOT normally present within a host. A. Disease B. Virulence C. Infection D. Pathogenicity

Infection

Why is polymyxin only used on the skin? 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. It has no effect on bacteria that live in the GI tract. It is sensitive to degradation by acid, making oral delivery unsuitable. It can disrupt the metabolic pathways found in humans.

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.

How does the protozoan Trypanosoma evade detection by the immune system? A. It can change the surface antigens frequently, preventing the immune system from tracking it. B. It can resist oxidation inside macrophages. C. It produces a capsule which is composed of polysaccharides similar to those found in the host. D. It prevents phagosome-lysosome fusion.

It can change the surface antigens frequently, preventing the immune system from tracking it.

How does the protozoan Trypanosoma evade detection by the immune system? It produces a capsule which is composed of polysaccharides similar to those found in the host. It can change the surface antigens frequently, preventing the immune system from tracking it. It prevents phagosome-lysosome fusion. It can resist oxidation inside macrophages.

It can change the surface antigens frequently, preventing the immune system from tracking it.

Why is a release of endotoxin into the bloodstream potentially deadly? A. It causes necrosis of the liver. B. Endotoxin can quickly enter the brain from the bloodstream, causing brain damage. C. It can lower blood pressure and cause the patient to go into shock. D. It results in dehydration of the patient.

It can lower blood pressure and cause the patient to go into shock

Eosin-methylene blue agar inhibits the growth of gram-positive organisms while allowing gram-negative organisms to grow. Colonies of lactose fermenters turn a blackish color while nonfermenters are colorless. How would you classify EMB? Is EMB a differential medium or a selective medium? Think about the meaning of the terms differential and selective to choose your answer. It is a differential medium and a selective medium. It is a selective medium only. It is neither differential nor selective. It is a differential medium only.

It is a differential medium and a selective medium.

Which of the following is FALSE about the Limulus amoebocyte test? A. It is an endotoxin assay. B. It is an exotoxin assay. C. It uses lysates of amoebocytes from the horseshoe crab. D. It detects endotoxins in cerebrospinal fluid.

It is an exotoxin assay.

Discuss two reasons why the lower respiratory tract is not normally colonized with microbiota

It is virtually free of microorganisms, mainly because of the efficient cleansing action of the epithelium which lines the tract. Any bacteria that does reach the lower respiratory is removed by coughing, sneezing, swallowing, etc. Mucus traps microbes and prevents them from moving further through the respiratory system. Cilia sweep the trapped microbes up and away from the lower respiratory tract. The air-flows slows as it moves through the respiratory tract. The abundance of macrophages in the lungs remove most microbes that arrive there.

How does the bobtail squid select only Aliiovibrio fischeri for colonization of the light organ? It produces nitric oxide in the mucus only. It produces nitric oxide in the mucus and light organ. It produces mucus that aggregates gram-negative bacteria. Aliiovibrio fischeri is present in very high numbers in marine environments, so it isn't necessary to select for it.

It produces nitric oxide in the mucus and light organ.

Immunoassays are techniques that use immunology to determine the presence of antigens, antibodies, or both. In one type of enzyme-linked immunoassay test, antibodies are attached to a matrix (such as the bottom of a microtiter plate). Next, the sample to be tested (such as patient serum) is added. An antibody-enzyme complex is then added. Finally, the enzyme substrate is added. The enzyme must catalyze a reaction that is visible (such as a color change), meaning that it is possible to see if the antibodies were present by seeing if there is a color change. The development of the colored product is proportional to the concentration of antibody. What would this sort of test be useful for? It would be useful for detecting whether a patient had antibodies for a particular pathogen. The second antibody (attached to the enzyme) is able to bind because it is specific for the antigen. It would be useful for detecting a virus in a patient's blood, as the antibody on the matrix would bind to the virus. The second antibody (attached to the enzyme) is able to bind because it is specific for the first antibody. It would be useful for detecting whether a patient had antibodies for a particular antigen. The second antibody (attached to the enzyme) is not necessary as the enzyme can react directly with the antigen if the antigen is present. It would be useful for detecting a virus in a patient's blood, as the antibody on the matrix would bind to the virus. The second antibody (attached to the enzyme) is able to bind because it is specific for the antigen.

It would be useful for detecting a virus in a patient's blood, as the antibody on the matrix would bind to the virus. The second antibody (attached to the enzyme) is able to bind because it is specific for the antigen.

Lactose-fermenting bacteria turn eosin-methylene blue medium from colorless to black or red. What causes this change? Lactose fermentation allows pyruvate to build up. This excess of pyruvate causes the color change. Lactose fermentation generates lactic acid. Lactic acid lowers the pH of the medium, causing the medium to change colors. Lactose fermentation generates lactate, making the medium more alkaline and causing the color change. Lactose fermentation generates alcohol. The alcohol reacts with chemicals in the medium to cause the color change.

Lactose fermentation generates lactic acid. Lactic acid lowers the pH of the medium, causing the medium to change colors.

Water supplies are treated with chlorine to kill pathogens. Chlorine reacts well with many other chemicals and bacterial cells because it is a strong oxidant. However, Legionella pneumophila can sometimes evade killing by residual chlorine. How does it do this? Legionella can detoxify chlorine by metabolizing it. Legionella tends to be found in warm waters and in aerosols, both situations in which the chlorine readily evaporates and, thus, is in lower concentration in the water. Legionella tends to form biofilms and infect other microbial cells as intracellular pathogens. Legionella produces cations that bind up the negative chloride ions, thus inactivating them.

Legionella tends to form biofilms and infect other microbial cells as intracellular pathogens.

Antifungal medications are often used topically. Why is this the case? Like human cells, fungal cells are prokaryotic. To develop systemic fungal medications requires finding specific characteristics of fungal cells that can be targeted, such as the ergosterol in fungal cell membranes. Like human cells, fungal cells are eukaryotic. To develop systemic fungal medications requires finding specific characteristics of fungal cells that can be targeted, such as the ergosterol in fungal cell membranes. It is not possible for fungi to cause systemic infections, so only topical treatments are needed. Fungi force cells to help them reproduce, making it difficult to target them without harming the host.

Like human cells, fungal cells are eukaryotic. To develop systemic fungal medications requires finding specific characteristics of fungal cells that can be targeted, such as the ergosterol in fungal cell membranes.

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? PCR followed by a nucleic acid hybridization technique to detect viral DNA or RNA an agglutination test immunofluorescence an immunoblot (Western blot) assay

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

What are leukocidins? Molecules that can degrade IgA Molecules that destroy the complement proteins Molecules that are capable of destroying phagocytes

Molecules that are capable of destroying phagocytes

Meningitis and gonorrhea are caused by A. Neisseria species. B. Pseudomonas species. C. measles virus.

Neisseria species.

Meningitis and gonorrhea are caused by Neisseria species. Pseudomonas species. measles virus.

Neisseria species.

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 in it. 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 water is toxic. B-No; the pond is likely to be anoxic. C-Yes; the pond is likely to be aerated. D-Yes; the pond water is high in nutrition for the fish.

No; the pond is likely to be anoxic.

If an electrophoresis gel is run with RNA and then a DNA probe is used to identify the fragments of interest, what is the process called? Northern blotting Eastern blotting Western blotting Southern blotting

Northern blotting

Which of the following does NOT occur during the development of dental caries? A. Streptococcus mutans produces dextran when sucrose is present. B. Oral microflora produce high concentrations of exoenzymes when sucrose is present. C. Lactic acid dissolves calcium phosphate, causing decalcification of the tooth enamel. D. Oral microflora produce high concentrations of organic acids.

Oral microflora produce high concentrations of exoenzymes when sucrose is present.

Bacteria that are resistant to sulfonamide have enzymes that have a greater affinity for what? PABA Sulfonamide Tetrahyrdrofolic acid Tetracycline

PABA

How might efflux pumps increase antibiotic resistance in bacteria? Resistant bacteria may have a greater number of efflux pumps on their cell surfaces. Some bacteria can decrease the specificity of their efflux pumps, increasing the number of different antibiotics the pumps can eliminate. Some bacteria can change the chemical structure of the antibiotic. Efflux pumps can never be modified to increase antibiotic resistance. Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.

Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.

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?

Species richness decreased and species abundance increased.

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 increased and species abundance decreased. B-Species richness increased and species abundance increased. C-Species richness decreased and species abundance increased. D-Species richness decreased and species abundance decreased.

Species richness decreased and species abundance increased.

Describe two situations in which a pathogen can act as an opportunistic pathogen

Staphylococcus aureus occurs as commensal on human skin but may cause staph infections. Pseudomonas aeruginosa is the most common cause of burn and external ear infections, and is the most frequent colonizer of medical devices (e.g.catheters).

Which of the following virulence factors would be found in Staphylococcus aureus? A. Streptokinase B. Hyaluronidase C. Collagenase D. Staphylokinase

Staphylokinase

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. Lactobacilli require sucrose in order to form biofilms on tooth surfaces. B. Sucrose and other purified sugars cause pitting of the tooth surfaces. C. Only purified sucrose and fructose can be fermented or produce acids in the oral cavity. D. Sucrose is required for the production of adhesive dextran by Streptococcus mutans.

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

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 __________. Sucrose and other purified sugars cause pitting of the tooth surfaces. Sucrose is required for the production of adhesive dextran by Streptococcus mutans. Lactobacilli require sucrose in order to form biofilms on tooth surfaces. Only purified sucrose and fructose can be fermented or produce acids in the oral cavity.

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

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 __________. Only purified sucrose and fructose can be fermented or produce acids in the oral cavity. Sucrose is required for the production of adhesive dextran by Streptococcus mutans. Lactobacilli require sucrose in order to form biofilms on tooth surfaces. Sucrose and other purified sugars cause pitting of the tooth surfaces.

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

How are superantigens different from other types of exotoxins? A. Superantigens only act against host neurons. B. Superantigens cause an overstimulation of the host immune system. C. Superantigens are comprised of two functional domains. D. Superantigens must be endocytosed into a target cell before becoming active.

Superantigens cause an overstimulation of the host immune system

Which of the following defense systems would be involved in fighting a viral pathogen? A. Complement system B. T lymphocytes C. Phagocytosis D. Humoral immunity

T lymphocytes

What is the role of the vir genes on a Ti plasmid? T-DNA transfer to confer resistance to viral infection to cause crow gall disease (virulence) replication of the plasmid

T-DNA transfer

TRUE OR FALSE: Protists are NOT normally found in the gastrointestinal tract of healthy individuals.

TRUE

TRUE OR FALSE: Some yogurts contain probiotics and prebiotics.

TRUE

TRUE OR FALSE: Vaginal acidity in the adult female is due to acid production by Lactobacillus acidophilus.

TRUE

How do arbuscular mycorrhizae (AM) help plants obtain more nutrients from the soil?

The AM increase the total surface area to absorb more nutrients

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

The bacterium is neither killed nor inhibited by the antibiotic.

How does a capsule help certain bacteria evade detection by the immune system? A. Capsules have the ability to destroy antibodies secreted by the immune system. B. The capsule makes the bacterium too sticky to be phagocytosed by the immune cells. C. The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign. D. Capsules allow the bacteria to stick together, creating a larger mass that is too big for immune cells to engulf.

The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.

How does a capsule help certain bacteria evade detection by the immune system? The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign. Capsules allow the bacteria to stick together, creating a larger mass that is too big for immune cells to engulf. The capsule makes the bacterium too sticky to be phagocytosed by the immune cells. Capsules have the ability to destroy antibodies secreted by the immune system.

The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.

How do phototrophic microorganisms benefit when associating with corals? Calcium and carbonate ions are released, which help buffer the pH and prevent dramatic pH shifts. The water's temperature in and around the coral skeleton is much warmer. The coral skeleton is an extremely efficient light-gathering structure that greatly enhances light harvesting for photosynthesis. The coral skeleton is used as a source of bicarbonate for the autotrophic growth of the phototrophs.

The coral skeleton is an extremely efficient light-gathering structure that greatly enhances light harvesting for photosyn

Which statement is TRUE about the fluid from the hydrothermal vents?

The fluid contains large amounts of reduced inorganic materials.

Disease research and epidemiology bring together many different facets to help us better understand disease pathology and spread. Which of the following statements are true? Select all that apply. The interactions that occur between a microbe and host influence the evolution of both. Some pathogens are able to cause disease within a host without penetrating the body. Intoxications result from a bacterial infection in which a large amount of bacterial toxin is produced. The ID50 value refers to the number of microbes needed to cause half of an infected population to die. Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host. The terms pathogenicity and virulence can be used interchangeably to describe the severity of an infection.

The interactions that occur between a microbe and host influence the evolution of both. Some pathogens are able to cause disease within a host without penetrating the body. Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host.

If a human is bitten by an animal that has rabies, then it is recommended that the human receive immune globin (human rabies antibodies) and a rabies vaccination (with inactive virus) as well. Which of the following is the best (and most specific) explanation for why both are recommended in this case? Hints The rabies vaccination is relatively new and ineffective, so it is important to give the immune globin as well to make certain that the viruses cannot cause disease. Because rabies is such a serious illness, using antibodies and a vaccine provides the strongest possible immediate protection. Both antibodies and the vaccine provide a rapid immediate response to prevent illness from developing. Using both is needed because an individual who has received this type of bite is more likely than someone else to receive another bite. While the immune globin is sufficient to prevent rabies infection, the vaccination helps to prevent the individual from the risk of a future bite. The rabies antibodies provide a rapid response but short-lived response while the vaccination provides slower but longer-lasting protection.

The rabies antibodies provide a rapid response but short-lived response while the vaccination provides slower but longer-lasting protection.

Considering that they require an oxygen-free environment, how do obligate anaerobes survive in the human body? They are able to use enzymes to convert reactive oxygen species to harmless molecules. They live inside of organelles, such as peroxisomes. 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). Obligate anaerobes are unable to survive in the human body.

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).

When a child begins to get its first teeth, what happens to the microbiota in the oral cavity? The teeth are rapidly colonized by anaerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms in the gingival crevices. The teeth are rapidly colonized by obligate anaerobes, in particular Fusobacterium, that are specifically adapted to growth in biofilms on the surfaces of the teeth. The teeth are rapidly colonized by aerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms on the surfaces of the teeth. The teeth are rapidly colonized by anaerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms on the surfaces of the teeth.

The teeth are rapidly colonized by anaerobes, in particular Streptococcus, that are specifically adapted to growth in biofilms on the surfaces of the teeth.

The yellow fever virus replicates in lymph nodes and in other immune system cells. How does it arrive in lymph nodes? It is injected there by the mosquitoes that carry the disease. The yellow fever virus is phagocytosed by white blood cells, and then travels through the lymph vessels. Lymph nodes contain white blood cells and filter lymph as it moves through the lymph vessels. White blood cells with yellow fever virus can become established there. Some viruses, like the yellow fever virus, can replicate inside of white blood cells like those in lymph nodes. The virus is carried to the lymph nodes by the blood stream. It is attracted to the lymph nodes by chemoattractants.

The yellow fever virus is phagocytosed by white blood cells, and then travels through the lymph vessels. Lymph nodes contain white blood cells and filter lymph as it moves through the lymph vessels. White blood cells with yellow fever virus can become established there. Some viruses, like the yellow fever virus, can replicate inside of white blood cells like those in lymph nodes.

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

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? Invasive procedures must use antibiotics. These procedures allow microbes from the skin to enter the bloodstream of the patient. Invasive procedures require long term hospital stays, thereby increasing the number of visitors seen by the patient. These procedures are carried out by health care workers, who carry resistant microbes.

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

How are immune cells able to detect foreign pathogens? A. They detect foreign, unfamiliar chemical substances released by the invading cells. B. They are able to detect structures on the surfaces of foreign cells that are not found in the host. C. They can compare the DNA sequences from the foreign cells to host DNA.

They are able to detect structures on the surfaces of foreign cells that are not found in the host.

How are immune cells able to detect foreign pathogens? They are able to detect structures on the surfaces of foreign cells that are not found in the host. They can compare the DNA sequences from the foreign cells to host DNA. They detect foreign, unfamiliar chemical substances released by the invading cells.

They are able to detect structures on the surfaces of foreign cells that are not found in the host.

How do fibrinolysins enhance a pathogen's virulence? A. They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin. B. They destroy the molecules that hold cells together. C. They destroy the fibers that are found at the base of superficial tissues, allowing for deeper penetration by the pathogen.

They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

How do fibrinolysins enhance a pathogen's virulence? They destroy the molecules that hold cells together. They destroy the fibers that are found at the base of superficial tissues, allowing for deeper penetration by the pathogen. They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system? A. They cause the immune system to destroy IgA antibodies. B. They cause fever, which destroys the complement proteins. C. They cause the immune system to turn on itself. D. They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.

They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen

How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system? They cause fever, which destroys the complement proteins. They cause the immune system to destroy IgA antibodies. They cause the immune system to turn on itself. They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.

They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.

A researcher wanted to determine the LD50 (lethal dose that kills 50% of the infected hosts) for a newly isolated bacterial pathogen. Mice were inoculated with diluted cultures containing between 101 and 107 cells. After two days, all of the mice had died EXCEPT for the uninoculated controls. Which of the following is the most likely explanation? Mice are not good model animals for this pathogen. The pathogen has become attenuated. This pathogen is highly virulent in mice. The pathogen has a very high LD50.

This pathogen is highly virulent in mice.

A researcher wanted to determine the LD50 (lethal dose50) for a newly-isolated bacterial pathogen. Mice were inoculated with diluted cultures containing between 101 and 107 cells. After two days, all of the mice had died, EXCEPT for the uninoculated controls. Which of the following is the most likely explanation? A. Mice are not good model animals for this pathogen. B. This pathogen is highly virulent in mice. C. The pathogen has become attenuated. D. The pathogen has a very high LD50

This pathogen is highly virulent in mice.

Our body is protected by the ___________ associated with epithelial tissues unless a pathogen can use _____________ to break through this barrier. A. Gap junctions/ hyaluronidase B. Tight junctions/ streptolysin C. Desmosome/ coagulase D. Tight junctions/ hyaluronidase E. Gap junctions/ lethicinase

Tight junctions/ hyaluronidase

Some studies have indicated that the ID50 for Vibrio cholerae can be as high as 108 organisms. Which of the following most likely explains the requirement for this relatively high ID50? V. cholerae does not produce enough virulence factors to overcome the host response and cause disease. Because V. cholerae cells are relatively small compared to host cells, thousands of bacteria must infect each cell to cause disease. Because the major virulence factor of V. cholerae is cholera toxin, large numbers of bacteria are required to produce enough toxin to cause disease. To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach.

To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach.

What is the role of epidemiology? To learn which organisms cause disease. To learn which medicines are effective at killing pathogens. To learn how to treat and prevent various diseases. To learn what diseases can be caused by respiratory pathogens.

To learn how to treat and prevent various diseases

Which of the following is predicted to result in the largest disease outbreak? a pathogen with a high R0 in an immunologically naïve population a pathogen with a high R0 in an immunized population a pathogen with a low R0 in an immunologically naïve population a pathogen with a high R0 in an immunized population

a pathogen with a high R0 in an immunologically naïve population

Reheating food to a temperature sufficient to kill bacteria is helpful in making food safer. However, is there a way that one can get food poisoning despite food having been reheated? No, it is not possible to develop food poisoning if all of the bacteria have been killed. Toxins may be heat-stable above temperatures that kill bacteria. Even if only a few bacteria survive, those bacteria may be sufficient to start an infection and produce toxins. Even if the toxins have been denatured, they can return to a functional form after cooling.

Toxins may be heat-stable above temperatures that kill bacteria.

Which of the following microorganisms actually grows inside the macrophage? Tuberculosis bacterium Shigella Leishmania Streptococcus pneumoniae Legionella

Tubercolosis bacterium

Which of the following microorganisms actually grows inside the macrophage? A. Legionella B. Tuberculosis bacterium C. Streptococcus pneumoniae D. Shigella E. Leishmania

Tuberculosis bacterium

Which of the following are properties of exotoxins? Select all that apply. Exotoxins are extremely heat stable. Very small amounts of exotoxin can be lethal. Exotoxins are released from the cell during death or replication. Exotoxins are protein molecules. Exotoxins target specific cellular structures or molecules. Exotoxins are produced primarily by gram-negative bacteria.

Very small amounts of exotoxin can be lethal. Exotoxins are protein molecules. Exotoxins target specific cellular structures or molecules.

On a global scale, the most important waterborne bacterial pathogens are __________. Vibrio cholerae and norovirus Salmonella enterica serovar Typhi and Escherichia coli Vibrio cholerae and Legionella pneumoniae Vibrio cholerae and Salmonella enterica serovar Typhi

Vibrio cholerae and Salmonella enterica serovar Typhi

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

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

Why would using nitrogenous fertilizer near a body of water affect the organisms in the body of water?

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 would endotoxins be released from a bacterial cell? A. When the cell dies B. When the cell attaches to a host cell in the human body C. When the cell moves toward a energy source D. During bacterial conjugation

When the cell dies

Wild rodents are the major reservoir of the plague organism, Yersinia pestis, but pandemic plagues were historically associated with crowded, unsanitary urban areas. Why is this the case? Yersinia pestis can be transmitted by fleas from wild rodents to urban rats, which quickly die of the disease. Humans are accidental hosts due to fleas seeking out blood meals after most rats have succumbed to the disease. Wild rodents tended to have high plague mortality rates, but most urban rats survived infection. This allowed the disease to be passed on to nearby humans by the vector. At one time, it was fashionable for city dwellers to keep rats as pets, bringing humans into close contact with these plague hosts. Crowded urban areas have more garbage and filth, allowing plague to spread more easily due to unsanitary conditions.

Yersinia pestis can be transmitted by fleas from wild rodents to urban rats, which quickly die of the disease.

A patient reported a headache, chills, vomiting, and diarrhea that occurred 12 hours after having a meal at home that included chicken. The physician suspected which type of organism? norovirus a food infection, most likely Enterohemorrhagic E. coli or Shigella a food infection, most likely Salmonella a food intoxication, most likely from Staphylococcus

a food infection, most likely Salmonella

The human oral microbiota consists of a. diverse aerobic and anaerobic microorganisms. b. monoculture biofilms on tooth surfaces. c. the small group of phylogenetically related aerobic microorganisms. d. the same phyla that are found in the human gut.

a. diverse aerobic and anaerobic microorganisms.

Which of the following will happen after a person takes an antibiotic orally? A. The growth of normal flora will be inhibited. B. The growth of pathogens will be inhibited. C. Opportunistic microorganisms such as antibiotic-resistant Staphylococcus will become established. D. all of the above

all of the above

An unknown bacterium was isolated from a patient with pneumonia. To determine the minimum inhibitory concentration of the chosen drug to use to treat the respiratory infection, the doctor must take into account __________. pH of growth medium all of the listed responses are correct time of incubation concentration of amino acids in the medium

all of the listed responses are correct

Deaths because of infectious disease are more common in developing countries, such as Africa, compared to the Americas because of __________. all of the listed responses are correct limited access to clean water limited immunization programs inadequate sanitation

all of the listed responses are correct

The rumen is an ________ habitat that depends on ________ to digest cellulose for ruminant animals. aerobic / cellulolytic and fermentative bacteria aerobic / cellulolytic fungi anaerobic / methanogens anaerobic / cellulolytic and fermentative bacteria

anaerobic / cellulolytic and fermentative bacteria

What metabolism would be favored when there is a lack of electron acceptors?

anaerobic fermentation

When the human papillomavirus (HPV) vaccine was first introduced to help prevent cervical cancer as well as anal warts and cancers, it was only recommended for 11- or 12-year-old girls. However, the CDC later expanded its HPV vaccination recommendations to include 11- and 12-year-old boys. By including males, the public health officials hoped to do all of the following EXCEPT __________. decrease the incidence of cervical cancer in women protect men from anal warts and cancer increase herd immunity to HPV decrease the basic reproductive number (R0) of HPV

decrease the basic reproductive number (R0) of HPV

Extensive growth of the streptococci in a thick bacterial layer on acidic glycoproteins on the teeth is called: A. dental plaque. B. dental caries. C. dental biofilm. D. periodontitis.

dental plaque

Extensive growth of the streptococci in a thick bacterial layer on acidic glycoproteins on the teeth is called periodontitis. dental plaque. dental caries. dental biofilm.

dental plaques

Antibiotics can alter gut microbiota. Which of the following is most likely to also alter gut microbiota? A. amount of sunlight a person is exposed to B. diet C. soaps, shampoos and deodorants D. exercise

diet

The structural and trophic foundation of coral reefs is a mutualistic relationship between dinoflagellates and stony corals (Cnidaria). cyanobacteria and sponges (Porifera). cyanobacteria and stony corals (Cnidaria). chemolithotrophic bacteria and stony corals (Cnidaria).

dinoflagellates and stony corals (Cnidaria)

Inactivates elongation factor 2 thus blocking protein synthesis

diphtheria toxin

The emergent H5N1 strain of avian influenza can occasionally be transmitted from birds to humans with a resulting 60% mortality rate (compared with a 2.5% mortality rate for the 1918 pandemic influenza). In 2012, after a single dead chicken in a wholesale market in Hong Kong tested positive for H5N1, all 17,000 chickens in the market and surrounding area were culled. This was an attempt to__________. quarantine . prevent migration. eliminate a vector. eliminate a reservoir.

eliminate a reservoir

A disease that is constantly present in a population at low numbers is a(n) __________. pandemic outbreak endemic epidemic

endemic

The methodology of microbial ecology includes

enrichment and isolation of specific microbes, cell-staining, and gene, transcript, and protein characterization.

Causes vomiting and diarrhea

enterotoxin A

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

ergosterol synthesis

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? high doses of antibiotics medical management with intravenous fluids to prevent dehydration and shock fecal transplants from a healthy donor surgical removal of the colon if antibiotic therapy fails

fecal transplants from a healthy donor

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________.

fermentation

Factors that enhance an organism's ability to adhere to host tissues include __________. A. lipopolysaccharide B. peptidoglycan C. fimbriae D. adherence enzymes

fimbriae

Which of the following is more likely to cause urinary tract infections? A. fimbriated strains of Escherichia coli B. non-fimbriated strains of Escherichia coli C. both fimbriated and non-fimbriated strains of Escherichia coli D. None of the answers are correct.

fimbriated strains of Escherichia coli

Botulinum toxin and tetanus toxin BOTH block the release of neurotransmitters, but botulinum toxin causes ________ whereas tetanus toxin causes ________. A. severe diarrhea / tissue necrosis B. tissue necrosis / severe diarrhea C. spastic paralysis / flaccid paralysis D. flaccid paralysis / spastic paralysis

flaccid paralysis / spastic paralysis

Illness that results from ingestion of pathogen-contaminated food is __________. foodborne disease food infection food poisoning food intoxication

food infection

The ability of Vibrio cholerae to cause disease depends on a number of factors. Which of the following are requirements for causing disease within a host? Select all that apply. gaining access to the host via a portal of entry depleting the host of nutrients at the site of infection adherence to host tissues direct damage of host tissues evasion of host defenses production of exotoxins

gaining access to the host via a portal of entry adherence to host tissues evasion of host defenses

For microbial biodiversity studies, it is common to identify the ________ rather than the ________ as a measure of biodiversity.

genes/ organisms themselves

Bacterial degradation of cellulose and fermentation of glucose occur in the rumen of cows, sheep and other ruminant animals. The main source of energy for the fermenters is __________, while the main source of energy for the ruminant is __________. glucose, volatile fatty acids volatile fatty acids, glucose glucose, methane H2, volatile fatty acids

glucose, volatile fatty acids

Culture-independent approaches avoid issues associated with

growing organisms in the lab

The image below shows a colorized transmission electron micrograph of Clostridium difficile, a Gram-positive, anaerobic member of the gut microbiota. Based on the image and information provided, which features contribute to the spread of C. difficile in a hospital environment? A. waxy walls B. hardy endospores C. ability to tolerate oxygen in the environment D. ability to attach to surfaces with fimbriae

hardy endospores

Staphylococcus aureus is a particularly dangerous organism when in food due to the enterotoxins some species produce. These toxins are dangerous because they are __________. acid-tolerant heat-stable superantigen toxins heat-stable, acid-tolerant superantigen toxins

heat-stable, acid-tolerant superantigen toxins

According to the animation, B cells interact directly with A. phagocytes. B. inflammation. C. helper T cells. D. the complement system.

helper T cells

For many years the CDC focused its seasonal influenza vaccination efforts on those groups in the population who suffered the highest influenza mortality rates, including the elderly aged 65 years and older. However, starting in 2008 the CDC shifted their focus to school-aged children and began recommending the vaccine for everyone aged at least 6 months. Research had shown no evidence for any protective effect of the vaccine in the elderly. By changing the recommendations for who should be vaccinated, the CDC planned to better protect the elderly by means of__________. vaccination. herd immunity. direct contact. acquired immunity.

herd immunity

The typical progression of symptoms for an acute infection would be __________. infection-acute period-incubation-decline period-convalescence incubation-acute period-infection-decline period-convalescence incubation-infection-acute period-decline period-convalescence infection-incubation-acute period-decline period-convalescence

infection-incubation-acute period-decline period-convalescence

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 flagella formation B-initiation of extracellular polysaccharide production C-formation of cell surface attachment proteins D-production of intercellular signaling molecules

initiation of flagella formation

Mucous membranes are a part of A. adaptive defense. B. the complement system. C. innate defense. D. humoral immunity. E. cell-mediated immunity.

innate defense

A person would be most at risk of infections if he or she __________. A)is a breast-feeding infant with a vegetarian mother who runs 5 miles a day B)is an active 30-year-old going through a divorce C)is a 70-year-old alcoholic whose spouse just died D)eats fast food every day of the work week and sleeps 9 hours a night

is a 70-year-old alcoholic whose spouse just died

A person would be most at risk of infections if he or she __________. A. is a 70-year-old alcoholic whose spouse just died B. is an active 30-year-old going through a divorce C. eats fast food every day of the work week and sleeps 9 hours a night D. is a breast-feeding infant with a vegetarian mother who runs 5 miles a day

is a 70-year-old alcoholic whose spouse just died

The diphtheria exotoxin is an A-B toxin that __________. A. is encoded for by genes in the chromosome of Corynebacterium diphtheriae cells B. is found only in Corynebacterium diphtheriae cells that have been infected with lysogenic bacteriophage β C. is found in all Corynebacterium diphtheriae cells D. causes host cell lysis

is found only in Corynebacterium diphtheriae cells that have been infected with lysogenic bacteriophage β

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

it can cause chronic inflammation

Borrelia burgdorferi is an interesting spirochete that is unusual when compared to other bacteria. Which of the following is the reason that it is so unusual? it has a cell wall it has ribosomes it has flagella it has a linear chromosome

it has a linear chromosome

What is the fate of H2 produced within a rumen? It is used in methanogenesis. It is transformed, along with other ions, into inorganic compounds. It is used in acetogenesis. It is released via eructation (belching).

it is used in methanogenesis

Which of the following was a downfall of the Human Microbiome Project? lack of subject diversity lack of subject numbers too few sample sites lack of female participants

lack of subject diversity

The skin is an effective barrier to the penetration of microorganisms because it has sebaceous glands that secrete ________ and ________, lowering the acidity of the skin to ________ and inhibiting colonization by many pathogens. A. salts / water / pH 7.4 B. hydroxyl ions / salts / pH 6 C. lactic acid / fatty acids / pH 5 D. salts / hydroxyl ions / pH 7.4

lactic acid / fatty acids / pH 5

Most marine Bacteria are thought to be chemoorganotrophs. Given the extremely low concentrations of nutrients in the open ocean, they typically need all of the following adaptations EXCEPT __________.

large cell size

Most marine Bacteria are thought to be chemoorganotrophs. Given the extremely low concentrations of nutrients in the open ocean, they typically need all of the following adaptations EXCEPT __________. proteorhodopsins many periplasmic binding proteins high surface area-to-volume ratios large cell size

large cell size

Produced by Clostridium perfringens and is also called alpha toxin. Digests phospholipids

lecithinase

Which of the following hemolysins is a phospholipase? lecithinase Streptolysin-O leukocidin Staphylococcal -toxin

lecithinase

The presence of microbes in the bladder is __________. likely to lead to a UTI used to prime the immune response more likely to occur in men than women normal

likely to lead to a UTI

Which of the following is NOT a constituent of the LPS subunits? A. membrane-distal O-polysaccharide B. membrane-proximal core polysaccharide C. lipid A D. lipid B

lipid B

Streptocoocus pyogens utilizes M protein and ________ to form microfibrils that facilitate attachment to host cells. A. lipoteichoic acid B. mucus C. plaque D. lipid A

lipoteichoic acid

Bacterial oxidation of Fe2+ occurs BEST under which environmental condition?

low (acidic) pH

Based on comparative studies of agricultural soils or polluted soils compared with undisturbed soils, disturbance of soil microbial communities tends to lead to __________.

lower prokaryotic diversity

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

lower prokaryotic diversity

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

lower the amount of free O2 in the root nodule

Staphyloccocus aureus is an important cause of food poisoning. Several gene-encoding exotoxins are associated with S. aureus food poisoning, including SEA, an exotoxin encoded by a viral gene. What sort of life cycle must this phage have? lytic cytocidal infections budding lysogenic

lysogenic

________ in saliva cleaves glycosidic linkages in peptidoglycan present in bacterial cell walls, weakening the wall and causing cell lysis. Mucus Lysozyme Lipid A Fibrin

lysozyme

After tuberculosis, malaria causes more annual deaths worldwide than any other single disease. Recent research has attempted to control the spread of malaria by genetically-modifying a bacterium (Pantoea agglomerans) commonly found in the guts of mosquitos to produce a toxin that kills the malaria parasite Plasmodium falciparum. If this project is effective it could significantly decrease the incidence of malaria because__________. malaria is a vectorborne disease. the mosquitoes will die. Pantoea agglomerans would be killed. malaria is a person-to-person disease.

malaria is a vectorborne disease.

Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning? sudden onset of diarrhea short incubation period moderate vomiting and fever severe abdominal cramping

moderate vomiting and fever

The incidence of disease in a population is termed the __________. prevalence morbidity mortality outbreak

morbidity

In the first reported epidemiological study in 1854, John Snow attempted to discover the source of a London cholera epidemic by going house-to-house and recording deaths. When he mapped the results, he was able to identify the Broad Street water pump as the likely source of contaminated water. The data collected in this study was__________. morbidity. incidence. prevalence. mortality.

mortality

Two organisms that both benefit from each other are in a symbiotic relationship called parasitism. commensalism. ammensalism. mutualism.

mutualism

Nearly 90% of all foodborne illnesses are associated with __________. norovirus, Salmonella, Clostridium perfringens, and Campylobacter jejuni norovirus, Salmonella, Clostridium perfringens, and Toxoplasma Salmonella, Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes Staphylococcus aureus, Salmonella, Clostridium perfringens, and Campylobacter jejuni

norovirus, Salmonella, Clostridium perfringens, and Campylobacter jejuni

Bacterial abundance (102 to 108) and generation times (days to centuries) vary by many orders of magnitude in the deep subsurface mainly due to __________.

nutrient limitations

One advantage of a monogastric digestive system is that __________. more microbes are present digestion occurs more slowly digestion occurs in compartments nutrients are easily accessible to the microbes that aid in digestion and vitamin production

nutrients are easily accessible to the microbes that aid in digestion and vitamin production

Legionella pneumophilia can grow in water and is transmitted in aerosols. Which of the following has NOT been linked to an infection? spas hot water tanks ocean water swimming pools

ocean water

Bacteria make up about ________ the weight of fecal matter. A. one-fourth B. one-third C. one-half D. one-fifth

one-third

Which of the following mammals is largely resistant to rabies infection? A. raccoons B. skunks C. opossums D. humans

opossums

The human microbiome contains all

organisms present in and on the body

Nitrification and anammox both

oxidize ammonia, but nitrification uses O2 and anammox uses NO2- for electron acceptors.

Microenvironments of soil exist where ________ concentrations greatly vary

oxygen, nitrate and sulfur

The process by which microorganisms cause diseases is known as LD50 (lethal dose50). pathogenesis. infection. virulence.

pathogenesis

The ability to cause disease is __________. infection virulence pathogenicity colonization

pathogenicity

The ability to cause disease is __________. virulence pathogenicity colonization infection

pathogenicity

Which of the following is NOT one of the three categories of exotoxins? A. cytolytic toxins B. AB toxins C. perforating toxins D. superantigen toxins

perforating toxins

Normal flora ________ colonization of pathogenic organisms. promote accelerate prevent maintain

prevent

Normal flora ________ colonization of pathogenic organisms. A. promote B. prevent C. maintain D. accelerate

prevent

Diazotrophs maximize nitrogenase activity by

producing specialized structures or fixing N2 at times when oxygen is absent to protect nitrogenase from oxygen

Capsules are particularly important for protecting bacteria from host defense mechanisms. making bacteria more vulnerable to host defense mechanisms. allowing bacteria to become more phagocytic. making bacteria less pathogenic.

protecting the bacteria from host defense mechanisms

Which of the following is NOT found in the gastrointestinal tract of a healthy individual? A. protists B. Clostridium C. Bacteroides D. Bacteroidetes

protists

During the 2002-2004 emergence and epidemic of Severe Acute Respiratory Syndrome corona virus (SARS-coV) the virus was found to be highly contagious, with an observed reproductive number (R) of 3.6. For this reason many rigorous means of infection control were instituted by the countries experiencing SARS outbreaks, including__________. culling of chickens. vaccination. quarantine and isolation. application of DDT to kill mosquitoes.

quarantine and isolation

Which of the following is NOT a physiological effect of endotoxin exposure? A. tissue necrosis B. hemorrhagic shock C. rapid increase in the numbers of lymphocytes E. fever

rapid increase in the numbers of lymphocytes

The Fe and Mn cycles include

reduced and oxidized forms that are very chemically reactive.

One microenvironment of the skin is an area where glands produce an oily substance called: A. mucus. B. sebum. C. fimbrae. D. lipid A.

sebum

Which of the following mutations would not result in antibiotic resistance? Missense mutation Nonsense mutation Silent mutation Frameshift insertion Frameshift deletion

silent mutation

Microbial diversity in an ecosystem can be expressed as the number of different species present, which is termed

species richness

Kills nucleated cells and acts as a hemolysin. Produces a membrane spanning pore

staphylococcal alpha toxin

Which of the following virulence factors would be found in Staphylococcus aureus? Hyaluronidase Collagenase Streptokinase Staphylokinase

staphylokinase

Causes RBC to break down (hemolysis)

streptolysin S and O

A person who attended a picnic early in the day develops a very high fever and is unresponsive by the evening. This person most likely has been exposed to a(n) A. enterotoxin. B. superantigen. C. membrane disrupting toxin. D. cytotoxin.

superantigen

Measles viruses are capable of inactivating host defenses by A. destroying complement proteins. B. producing superantigens. C. suppressing the immune system. D. producing leukocidins.

suppressing the immune system

Measles viruses are capable of inactivating host defenses by producing leukocidins. producing superantigens. destroying complement proteins. suppressing the immune system.

suppressing the immune system

Termites are capable of digesting cellulose and hemicellulose due to the presence of __________. enzymes that digest these compounds symbiotic bacteria in their gut endosymbiotic bacteria none of the listed responses

symbiotic bacteria in their gut

Karen stepped on a rusty nail while walking her dog barefoot. She needs to be treated to prevent damage by which exotoxin? A. tetanus exotoxin B. hemolysin C. cholera exotoxin D. botulinum exotoxin

tetanus exotoxin

Binds to inhibitory interneurons blocking the release of glycine. Causes spastic paralysis

tetanus toxin

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 __________.

the C and N cycles are closely coupled

One important difference between the C, N, and S cycles and the P, Ca, and Si cycles is that

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

Saliva contains relatively few microbes compared to other body sites, because __________. the concentration of lipids limits their growth the temperature of saliva does not support microbial growth the concentration of antimicrobial enzymes limits their growth the pH is too low

the concentration of antimicrobial enzymes limits their growth

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

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

Lichens are a mutualistic association of a fungus and either an alga or a cyanobacterium in which

the fungus protects the photosynthetic partner from erosion

During the early 20th century, pandemics typically took months to years to span the globe, while the 2009 H1N1 swine flu spread globally within weeks and had affected most countries within 6 months. This difference in the rate of spread is mainly due to__________. more human contact with wild and domestic animals worldwide. the increased virulence of the pathogens. the increased volume and speed of global transportation. the emergence of antibiotic resistance.

the increased volume and speed of global transportation.

In mycorrhizal mutualisms between plants roots and fungi

the plant supplies carbohydrates to the fungus and the fungus supplies phosphorus and nitrogen to the plant.

A farmer wants to acidify his alkaline soils by adding elemental sulfur (S0), which will, under the right conditions, be oxidized to H2SO4 by chemolithotrophs. However, the weather report predicts heavy rains and possible localized flooding starting within in a few days and lasting for the next couple of weeks. Why should the farmer wait to apply the S0 to his fields until the soils are well-drained?

to avoid production of hydrogen sulfide (H2S) due to anoxia

The ingestion of a large number of Vibrio cholerae cells is necessary for infection. Why is such a large concentration of bacteria needed? to ensure enough survive the low pH in the stomach to establish infection to ensure enough bacteria survive the enzymes in our mouth because a large number of bacteria are required to overcome the specificity of our immune system because they must compete with bacteria in our intestines

to ensure enough survive the low pH in the stomach to establish infection

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

to treat with the oldest, effective antimicrobial

The lipid A portion of LPS is responsible for ________, and the polysaccharide fraction makes the complex ________ and ________. A. virulence / insoluble / immunogenic B. toxicity / water-soluble / immunogenic C. toxicity / insoluble / pathogenic D. virulence / nonpolar / insoluble

toxicity / water-soluble / immunogenic

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 __________.

typically grow slower than in pure culture

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-carry out completely different metabolisms than in pure culture B-typically grow slower than in pure culture C-typically grow faster than in pure culture D-typically grow only on surfaces

typically grow slower than in pure culture

The common methods to control the spread of West Nile virus include __________. using insect repellents wearing loose-fitting clothes when outside a vaccine for humans providing water in yards for birds to drink

using insect repellents

Certain traits that allow pathogens to create infection and cause disease are termed A. hyaluronidases. B. collagenases. C. streptokinases. D. virulence factors.

virulence factors

Certain traits that allow pathogens to create infection and cause disease are termed streptokinases. collagenases. virulence factors. hyaluronidases

virulence factors