Chapter 25 Microbiology

________ can vary between strains of an organism depending on the ability to adhere, colonize, and invade a host. a.Attenuation b.Virulence c.Disease d.Infection

B

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as A. Virulence-50. B. LD50 (lethal dose50). C. Antigen dose50. D. Death rate-50.

B

Which of the following does NOT occur during the development of dental caries? a.Streptococcus mutans uses dextran to attach to teeth and gums. 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 biofilm microflora produce high concentrations of organic acids.

B

Which of the following is NOT a subunit of lipopolysaccharide (LPS)? A. O-specific polysaccharide B. M protein C. core polysaccharide D. lipid A

B

Which of the following is NOT an example of an AB toxin? A. shiga-like toxin B. hemolysins C. tetanus toxin D. botulinum toxin

B

Which of the following is NOT important for the adherence of bacteria to host tissues? A. capsule B. lipopolysaccharides C. slime layer D. adhesins

B

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

B

Septicemia is an example of a A. autoimmune infection. B. localized infection. C. systemic infection. D. transient infection.

C

A bacterial infection becomes a disease when a.the growth of normal flora is inhibited. b.the immune system is triggered. c.the organisms attach to host cells. d.there is tissue damage that impairs host function.

D

Siderophores are A. molecules that aid directly in attachment to host cells. B. toxins that affect the gastrointestinal tract. C. inorganic molecules that help in active transport. D. organic molecules that help pathogens take up iron.

D

An endogenous pyrogen is A. a chemical released by a bacterial cell that causes fever. B. a chemical produced by a host's own immune system that causes fever. C. a chemical produced within a bacterial cell that is released during cell division or at death of the bacterium, at which point it causes fever. D. a chemical from the bacterial cell wall that causes fever.

B

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.

B

Genes for antiphagocytic proteins, exotoxins, and adherence that are clustered together on a bacterial chromosome are called a.virulence islands. b.pathogenicity islands. c.infection islands. d.operons.

B

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

B

Pathogenicity is the ability A. of the host to resist damage by the pathogen. B. of the pathogen to inflict damage on the host. C. of the host to inflict damage on the pathogen. D. None of these are correct.

B

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

B

________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts. A. Pathogenic infections B. Healthcare-associated infections C. Virulent infections D. Immunocompromised infections

B

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 d.fever

C

Growth of a microorganism after entering a host is called a.colonization. b.infection. c.invasion. d.disease.

A

Organism X has an LD50 of 2 x 102, and organism Y has an LD50 of 3 x 104. Which organism is more virulent? a.organism X b.organism Y

A

Pathogenicity and virulence differ in that A. pathogenicity refers to the overall ability of a microbe to cause disease, whereas virulence refers to the ability of one microbe to cause disease relative to another. B. virulence refers to the overall ability of a microbe to cause disease, whereas pathogenicity refers to the ability of one microbe to cause disease relative to another. C. virulence only refers to pathogens, whereas pathogenicity refers to any microbe that can cause an infection. D. pathogenicity only refers to pathogens, whereas virulence refers to any microbe that can cause an infection.

A

Streptokinase works to ________ fibrin clots while coagulase works to ________ fibrin clots. a.dissolve / promote b.promote / dissolve c.form / bust d.promote / target

A

The following bacterial genera are all implicated in dental caries EXCEPT A. Borrelia. B. Streptococcus. C. Corynebacterium. D. Fusobacterium.

A

The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called A. septicemia. B. cancer. C. bacteremia. D. pathogenesis.

A

The α-toxin of Clostridium perfringens is A. a lecithinase. B. an enterotoxin. C. an endotoxin. D. a superantigen toxin.

A

Which of the following is a reason that specific pathogens tend to infect specific tissues? A. There are chemical and physical differences between tissues. B. Microbes preferentially target external tissues, such as skin, as the environment is more favorable for their growth than inside the body. C. Some tissues have receptors for microbes, but others do not. D. Tissues with neutral pH are colonized but those with acidic or alkaline pH are not.

A

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

A

Pathogens that can secrete ________ are more virulent because of the organisms potential to spread in the host. a.cellulase b.hyaluronidase c.urease d.nuclease

B

Patients that are HIV+ are at greater risk of ________ than the average population. a.cytolytic infections b.opportunistic infections c.latent infections d.virulent infections

B

Salmonella species use ________ to facilitate attachment to gastrointestinal tissue. A. pili B. type I fimbriae C. antiphagocytic proteins D. siderophores

B

The ability of a pathogen to enter a cell, spread, and cause disease is termed a.pathogenesis. b.invasion. c.colonization. d.adherence.

B

The condition that results when some bacteria are shed in the bloodstream and distributed to distant parts of the body but do not reproduce in the blood is called A. erythemia. B. bacteremia. C. uremia. D. septicemia.

B

Receptors on the surface of pathogens that are made of glycoproteins and lipoproteins are called a.capsules. b.slime layers. c.adhesins. d.adhesives.

C

Tetanus toxin causes A. severe diarrhea. B. muscles to be unable to contract. C. muscles to be unable to relax. D. hemolytic uremic syndrome.

C

The collective term for the organisms living on or in the human body, as opposed to a general term for organisms in an environmental habitat, is A. transient microbial flora. B. pathogens. C. the human microbiome. D. the microbiota.

C

The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called A. biofilms. B. capsules. C. glycocalyx. D. lipid A.

C

The process by which white blood cells ingest and kill bacteria is called A. transcription. B. exocytosis. C. phagocytosis. D. translation.

C

What is the difference between adherence and colonization? A. Colonization occurs when microbes begin to spread in host tissues, whereas adherence occurs when microbes initially attach. B. Colonization occurs when microbes begin to spread in host tissues, whereas adherence occurs when microbes first begin to reproduce in the host tissues. C. Colonization occurs when a microbe begins to grow in host tissues whereas adherence occurs when the microbe initially attaches. D. Colonization occurs when transient microbes are on a tissue, whereas adherence is a more permanent attachment to cells.

C

Which of the following hemolysins is a phospholipase? A. Staphylococcal α-toxin B. leukocidin C. lecithinase D. streptolysin-O

C

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

C

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

C

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

C

________ is the growth of microorganisms NOT normally present within a host. a.Disease b.Virulence c.Infection d.Pathogenicity

C

Which cell structure is important in adherence? cell wall b.fimbria c.teichoic acid d.lipopolysaccharide

B

Which of the following pathogens does NOT use capsules or a slime layer for attachment? A. Streptococcus pneumonia B. Vibrio cholera C. Bacillus anthracis D. All of these pathogens use capsules or slime layers for attachment.

B

Which of the following toxins is NOT a cytolytic exotoxin? a.hemolysin b.Shiga toxin c.leukocidin d.phospholipase

B

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.

False

Pathogens that have entered the bloodstream and are producing toxins are the cause of a.toxemia. b.bacteremia. c.septicemia. d.viremia.

C

Cytolytic toxins A. are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane. B. damage host cytoplasmic membrane. C. are extracellular proteins. D. cause cell lysis and death.

A

Decalcification of the tooth enamel is caused by A. lactic acid. B. lipopolysaccharide. C. formic acid. D. dextrans.

A

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

A

Exotoxins classified as AB toxins damage cells by a. using the B subunit to attach to the target cell while the A subunit enters and inhibits protein synthesis. b. using the A subunit to attach to the target cell while the B subunit enters and inhibits protein synthesis. c. using the A subunit to attach to the target cell while the B subunit enters and inhibits DNA synthesis. d. using the B subunit to attach to the target cell while the A subunit enters and inhibits DNA synthesis.

A

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

B

Epithelial cells lining the respiratory tract form a A. connective tissue layer. B. mucous membrane. C. impenetrable barrier to infection. D. dry and rigid barrier with tight junctions between cells.

B

Because they are Gram negative, E. coli, Salmonella, and Shigella all produce a.exotoxins. b.cytolytic toxins. c.endotoxins. d.enterotoxins.

C

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

C

Diptheria toxin is a A. cytolytic toxin. B. type of endotoxin. C. AB toxin. D. superantigen toxin.

C

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

C

Adherence factors include ALL of the following EXCEPT a.capsules. b.fimbriae. c.flagella. d.lipopolysaccharide layers.

D

All of the following are enzymes that increase virulence EXCEPT a.proteases. b.nucleases. c.lipases. d.cellulases.

D

An outer coat consisting of a dense, well-defined polymer layer surrounding a cell and used in attachment is called a A. cytoplasmic membrane. B. lipopolysaccharide layer. C. pilus. D. capsule.

D

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

D

Lysozyme is found throughout our bodies to protect us from infection. Some bacteria are able to evade this defense a.by deactivating the enzyme. b.by altering their plasma membrane. c.by altering their outer membrane. d.by altering their peptidoglycan.

D

Neisseria gonorrhoeae can cause infection by a.producing enzymes that degrade peptidoglycan. b.producing virulence factors that breakdown cellulose. c.producing enzymes that modify their cell wall to evade lysozyme. d.producing enzymes that destroy antibodies on the surface of mucosal cells.

D

Shiga toxin is an enterotoxin that is produced by A. Vibrio cholerae. B. Clostridium tetani. C. Escherichia coli O157:H7. D. Shigella dysenteriae.

D

Staphylococcus aureus and Streptococcus pyogenes strains can produce ________ that cause the severe and sometimes life-threatening symptoms of toxic shock syndrome. A. endotoxin B. cytolytic C. AB toxins D. superantigen toxins

D

The best term to describe the general process by which microorganisms cause diseases is known as A. infection. B. virulence. C. invasion. D. pathogenesis.

D

The decrease or loss of virulence of a pathogen is referred to as A. aging. B. disinfectivity. C. lethal dose. D. attenuation.

D

Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen? A. rubella B. measles C. mumps D. malaria

D

Which genus produces hyaluronidase? A. Procholorococcus B. Mycobacterium C. Shigella D. Streptococcus

D

Which of the following does NOT affect pathogen growth? A. temperature B. pH C. availability of microbial nutrients D. All of these answer choices affect growth.

D

Which of the following is TRUE about flagella? A. They are not involved in adherence and colonization at all. B. They are the most important structure in adherence. C. They are as important in adherence as pili and fimbriae. D. They may be involved in adherence to a lesser extent than pili and fimbriae.

D

Which of the following is a category of exotoxin? A. lipophilic toxin B. α-toxin C. β-toxin D. cytolytic toxin

D

Which of the following is an important factor in the development of dental caries? A. high acid diet B. low salt diet C. high salt diet D. high sugar diet

D

________ is a damage or injury to a host organism that impairs its function. A. Transmission B. Trauma C. Infection D. Disease

D

________ organisms are valuable in the production of vaccines. a.Infectious b.Pathogenic c.Virulent d.Attenuated

D