Mastering Microbiology - Exam #3 - Ch 12, 13, 15

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

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

Which of the following is a human disease caused by prions? subacute sclerosing panencephalitis (SSPE) shingles Creutzfeldt-Jakob disease (CJD) chickenpox (varicella)

Creutzfeldt-Jakob disease (CJD)

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

B domain

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

Neisseria species

From which phrase is the term "prions" derived? Particles of infection Proteinaceous infectious particles Protein infections Protein infection of the nervous system

Proteinaceous infectious particles

Biofilms provide pathogens with an adhesion mechanism and aid in resistance to antimicrobial agents. True False

True

Most drugs that interfere with viral multiplication also interfere with host cell function. True False

True

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

When the cell dies

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

neurotoxin

Endotoxins are molecules that bind nerve cells. associated with gram-positive bacteria. A-B toxins. part of the gram-negative cell wall. excreted from the cell.

part of the gram negative cell wall

The definition of lysogeny is -when the burst time takes an unusually long time. -the period during replication when virions are not present. -phage DNA is incorporated into host cell DNA. -attachment of a phage to a cell. -lysis of the host cell due to a phage.

phage DNA is incorporated into host cell DNA

A clear area against a confluent "lawn" of bacteria is called a plaque. pock. phage. rash. cell lysis.

plaque

A virus's ability to infect an animal cell depends primarily upon the type of viral nucleic acid. enzymatic activity of a host cell. presence of pili on the host cell wall. presence of receptor sites on the cell membrane. host cell's ability to phagocytize viral particles.

presence of receptor sites on the cell membrane.

An infectious protein is a papovavirus. bacteriophage. viroid. prion. retrovirus.

prion

An envelope is acquired during which of the following steps? release biosynthesis penetration adsorption uncoating

release

Enveloped viruses have a layer of lipids surrounding their capsid. This envelope is made mostly of host cell membrane. In which step does the virus acquire this envelope? assembly attachment synthesis release

release

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) superantigen. membrane disrupting toxin. cytotoxin. enterotoxin.

superantigen

Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to A-B toxins. lipid A. superantigens. erythrogenic toxin. membrane-disrupting toxins.

superantigens

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

suppressing the immune system

Symptoms of protozoan and helminthic diseases are due to -tissue damage due to growth of the parasite on the tissues, waste products excreted by the parasite, and products released from damaged tissues. -products released from damaged tissues. -tissue damage due to growth of the parasite on the tissues and waste products excreted by the parasite. -tissue damage due to growth of the parasite on the tissues. -waste products excreted by the parasite.

tissue damage due to growth of the parasite on the tissues, waste products excreted by the parasite, and products released from damaged tissues.

An example of a latent viral infection is cold sores. mumps. influenza. smallpox. subacute sclerosing panencephalitis.

cold sores

What disease does the human herpesvirus-1 cause? canker sores chancres cold sores or fever blisters infectious mononucleosis

cold sores or fever blisters

In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used? -to check for enterotoxins -to detect the presence of the botulinum toxin -to ensure that a sterilized medical device is free of endotoxin -to confirm the diagnosis of gas gangrene

to ensure that a sterilized medical device is free of endotoxin

All of the following contribute to a pathogen's invasiveness EXCEPT hyaluronidase. coagulases. toxins. cell wall components. capsules.

toxins

f the following is true concerning a lysogenic viral replication cycle? -During lysogeny, the viral DNA is present as a circular plasmid. -During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome. -Lysogenic infections are similar to persistent infections in that virus is constantly produced. -Once the lysogenic portion of the cycle has begun, virus is never produced again.

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

In what year did Stanley Prusiner discover prions? 1979 1928 1982 1997

1982

All of the following are used by bacteria to attach to host cells EXCEPT M protein. fimbriae. capsules. ligands. A-B toxins.

A-B toxins

Which of the following would be an example of an infection initiated via the parenteral route? -An individual contracts hepatitis B from an accidental stick with a contaminated needle. -An individual contracts gonorrhea as a result of unprotected sex. -An individual contracts a hookworm infection as a result of walking around outside barefoot. -An individual contracts a gastrointestinal infection by consuming contaminated water.

An individual contracts hepatitis B from an accidental stick with a contaminated needle.

Which of the following is true regarding cultivation and isolation of animal viruses? -Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host. -Viruses can be easily grown in liquid culture without any other organisms present. -The preferred and widely used method of viral isolation and growth is via growth in an embryonated egg. -Mouse models are available for virtually all human viral infections and can be routinely used for vaccine development.

Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host.

Which of the following statements about lysogenic conversion is true? -Lysogenic conversion is a result of the transfer of plasmids from one bacterium to another. -Lysogenic bacteria are always less virulent than non-lysogenic bacteria because the viral infection weakens them. -Endotoxin production by bacteria is frequently the result of a lysogenic infection. -Exotoxin production by bacteria is frequently the result of a lysogenic infection.

Exotoxin production by bacteria is frequently the result of a lysogenic infection.

In A-B exotoxins, the A component binds to the host cell receptor so that the B component can enter the cell. True False

False

In general, the LD50 for exotoxins is much greater than the LD50 for endotoxins. True False

False

Viruses that utilize reverse transcriptase belong to the virus families Hepadnaviridae and Retroviridae. Retroviridae and Picornaviridae. Herpesviridae and Retroviridae. Herpesviridae and Poxviridae. Rhabdoviridae and Herpesviridae.

Hepadnaviridae and Retroviridae.

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

Hyaluronidase

How does the protozoan Trypanosoma evade detection by the immune system? -It prevents phagosome-lysosome fusion. -It can resist oxidation inside macrophages. -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 can change the surface antigens frequently, preventing the immune system from tracking it.

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

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

Which of the following statements regarding latent viral infections is true? -During latent infections, small amounts of virus are produced, and virus numbers build up over time. -Latent viral infections are caused by the slow conversion of cellular glycoproteins from normal to infectious form. -Latent viral infections are almost always fatal. -Latent infections can persist for years in an individual without causing any symptoms.

Latent infections can persist for years in an individual without causing any symptoms.

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

Lipid A

Where is the site of Shigella attachment in the host? Phagocytes Leukocytes Intestinal epithelial cells M cells

M cells

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

Molecules that are capable of destroying phagocytes

Which of the following statements about adherence is true? -Most bacteria can adhere to any cell in the host. -Adhesins are always located on the bacterium's cell membrane. -The host cell receptors for bacterial adhesins are usually proteins. -Most bacterial adhesins are glycoproteins or lipoproteins.

Most bacterial adhesins are glycoproteins or lipoproteins.

Which of the following statements concerning prion diseases is true? -Prion diseases affect brain function but do not affect the morphology (overall appearance) of brain tissues. -Prion diseases affect humans but not other animals. -Prion diseases are always inherited. -Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).

Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).

Which statement regarding endotoxins is true? -One consequence of endotoxins is the activation of blood-clotting proteins. -Endotoxins are part of the outer portion of the cell wall of gram-positive bacteria. -Endotoxins induce host cells to produce effective antitoxins that help to protect them against the toxin's effects. -The effects of endotoxins vary greatly, depending on the specific bacterium the produces them.

One consequence of endotoxins is the activation of blood-clotting proteins.

You are given an unknown, pure sample of a eukaryotic organism. Which of the following tests would allow you to determine if the sample contains algae? -Determine if the organism is unicellular by microscopy. If it is unicellular, it is an alga. -Inject the organism into a lab animal. If it does not cause disease, it is an alga. -Place the sample in a clear container filled with media containing no sugars, and leave it in a sunny window. After a few weeks, look for growth of the organism. -Perform a biochemical test for the presence of chitin.

Place the sample in a clear container filled with media containing no sugars, and leave it in a sunny window. After a few weeks, look for growth of the organism.

What is the etiologic agent of typhoid? Salmonella E. coli Shigella

Salmonella

In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true? -Staphylococcal enterotoxin is the more lethal of the two toxins. -More organisms of Staphylococcal bacteria must be ingested to cause infection, as compared to Shigella bacteria. -The parenteral route is the preferred portal entry for Shigella bacteria. -Shiga toxin is more lethal than staphylococcal enterotoxin.

Shiga toxin is more lethal that staphylococcal enterotoxin

Which statement concerning viral structure is true? -All viruses contain an envelope, which is made of lipid, carbohydrate, and protein. -Animal viruses usually contain tail sheaths and spikes. -The proteins in the envelope are capsomeres. -Spikes are found on some viruses. They are very consistent in structure and can be used for identification.

Spikes are found on some viruses. They are very consistent in structure and can be used for identification.

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

Staphylokinase

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

Superantigens cause an overstimulation of the host immune system.

Which of the following statements concerning viruses is true? -Viruses are usually about the same size as bacteria. -Viruses contain both DNA and RNA, and they undergo binary fusion. -The "host range" for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach. -Viruses possess enzymes for protein synthesis and ATP generation.

The "host range" for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.

How does a capsule help certain bacteria evade detection by the immune system? -Capsules have the ability to destroy antibodies secreted by the immune system. -The capsule makes the bacterium too sticky to be phagocytosed by the immune cells. -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.

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.

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? -The DNA is chewed up by enzymes found in the recipient cell. -The DNA begins to replicate without integrating into the host chromosome. -The host DNA integrates, with the prophage, into the new recipient chromosome.

The host DNA integrates, with the prophage, into the new recipient chromosome.

How does specialized transduction differ from regular lysogeny? -The prophage is not excised during specialized transduction. -The resulting bacteriophage from specialized transduction cannot infect a new host cell. -The resulting bacteriophage from specialized transduction does not contain any viral DNA. -The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? -The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells. -The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA. -The phage causes the destruction of any antibiotic present during the specialized transduction process.

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient? -The virus is slowly killing the patient's cells. -The virus is incorporating its nucleic acid with that of the patient's cells. -The virus is infecting cells and then releasing only small amounts of virus. -The virus is causing the death of the infected cells in the patient. -The virus is not killing any cells in the host.

The virus is causing the death of the infected cells in the patient.

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.

What do hyaluronidase and kinase have in common? -They both break down components of the extracellular matrix. -They are both enzymes involved in evading host defense. -They both directly prevent phagocytosis. -They are both critical components of microbial capsules. -All of the above are correct.

They are both enzymes involved in evading host defense.

How do fibrinolysins enhance a pathogen's virulence? -They destroy the fibers that are found at the base of superficial tissues, allowing for deeper penetration by the pathogen. -They destroy the molecules that hold cells together. -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 Shigella cells move between host cells? -They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another. -They are secreted directly into the epithelial cells from the M cells. -They are secreted by phagocytes. -They lyse the M cell, releasing thousands of new cells to infect other host cells.

They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another.

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

How are viruses different from cells? They do not contain genetic material. They do not contain protein. They require a host in order to reproduce. They do not contain enzymes.

They require a host in order to reproduce

What is the function of the structural elements of a virus? To package and protect the viral genome To use all of the cell proteins To provide a source of energy for the virus

To package and protect the viral genome

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

Tuberculosis bacteriumq

Which of the following toxins and descriptions do NOT match? -tetanus toxin: an A-B neurotoxin that causes uncontrollable muscle contractions -Vibrio enterotoxin: a superantigen that destroys epithelial cells -hemolysins: membrane-disrupting toxins that destroy erythrocytes -streptococcal erythrogenic toxin: a superantigen that damages capillaries and results in a characteristic rash

Vibrio enterotoxin: a superantigen that destroys epithelial cells

Which of the following is true of viroids? -Viroids are short pieces of naked RNA. -Viroids are typically extremely long and contain numerous genes. -Viroid is the term for a virus that infects plants. -There are similarities between the base sequences of viroids and exons, resulting in the hypothesis that viroids evolved from exons.

Viroids are short pieces of naked RNA.

How do all viruses differ from bacteria? Viruses are not composed of cells. Viruses are filterable. Viruses do not reproduce. Viruses do not have any nucleic acid. Viruses are obligate intracellular parasites.

Viruses are not composed of cells.

What is the key difference between yeast and mold? -Yeast have cellulose cell walls, while mold has chitin cell walls. -Yeast is a fungus, while mold is an alga. -Yeast is unicellular, while mold is multicellular. -Yeast is colonial, while mold is multicellular.

Yeast is unicellular, while mold is multicellular.

Which of the following virulence factors could directly prevent phagocytosis and/or phagocytic degradation? waxy lipids capsules M proteins all of the above none of the above

all of the above

Which of the following is NOT a cytopathic effect (CPE) of viruses? the formation of a syncytium chromosomal changes in the host cell formation of inclusion bodies All of the above are possible

all of the above possible

We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing? synthesis attachment assembly uncoating

attachment

Which of the following is NOT used as a criterion to classify viruses? biochemical tests number of capsomeres size morphology nucleic acid

biochemical tests

The mechanism whereby an enveloped virus leaves a host cell is called transduction. lysogeny. abduction. penetration. budding.

budding

The most conclusive evidence that viruses cause cancers is provided by -some liver cancer patients having had hepatitis. -treating cancer with antibodies. -finding oncogenes in viruses. -the presence of antibodies against viruses in cancer patients. -cancer following injection of cell-free filtrates.

cancer following injection of cell-free filtrates

Oncogenic viruses are genetically unstable. cause tumors to develop. are lytic viruses that kill the host cell. cause acute infections. have no effect on the host cell.

cause tumors to develop

Which of the following does NOT contribute to the symptoms of a fungal disease? metabolic products capsules cell walls toxins allergic response of the host

cell walls

Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage? yellow fever ringworm influenza cholera

cholera

Which of the following is NOT utilized to culture viruses? animal cell cultures embryonated eggs culture media bacterial cultures laboratory animals

culture media

Superantigens produce intense immune responses by exotoxins. interferons. endotoxins. cytokines. leukocidins.

cytokines

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

cytotoxin

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

fever

Which type of bacterial enzyme helps spread Streptococcus pyogenes by digesting blood clots? coagulase collagenase hyaluronidase fibrinolysin

fibrinolysin

Which of the following features of Salmonella prevent it from being phagocytosed? Invasins Flagella Fimbriae

flagella

Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages kill human cells. kill the bacteria, causing release of endotoxins. carry plasmids. give new gene sequences to the host bacteria. produce toxins.

give new gene sequences to the host bacteria

All of the following are examples of entry via the parenteral route EXCEPT injection. hair follicle. surgery. skin cut. bite.

hair follicle

A viroid is a(n) infectious piece of RNA without a capsid. capsid without nucleic acid. infectious protein. complete, infectious virus particle. provirus.

infectious piece of RNA without a capsid

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves replication of viral nucleic acid. adsorption to specific receptors. lysis of the host cell. assembly of viral components. injection of naked nucleic acid into the host cell.

injection of naked nucleic acid into the host cell.

Where do Salmonella pathogens grow and replicate in the infected host? Inside M cells Inside phagocytes Inside Shigella cells Inside intestinal epithelial cells

inside phagocytes

Siderophores are bacterial proteins that compete with the host's receptors. iron-transport proteins. red blood cells. antibodies. white blood cells.

iron-transport proteins

Which of the following statements is NOT true of lysogeny? -It is a "silent" infection; the virus does not replicate. -It can give infected pathogens the genetic information for toxin production. -Prophage is inserted into the host genome. -Lytic cycle may follow lysogeny. -It causes lysis of host cells.

it causes lysis of host cells

The most frequently used portal of entry for pathogens is the mucous membranes of the gastrointestinal tract. parenteral route. mucous membranes of the respiratory tract. skin. All of these portals are used equally.

mucous membranes of the respiratory tract.

Which of the following contributes to the virulence of a pathogen? -toxin production -numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production -evasion of host defenses -numbers of microorganisms that gain access to a host -numbers of microorganisms that gain access to a host and evasion of host defenses

numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

Which disease did Stanley Prusiner first identify as being caused by prions? Fatal familial insomnia Mad cow disease Scrapie Kuru

scrapie

Endotoxins in sterile injectable drugs could cause no damage, because they are sterile. septic shock symptoms. infection. giant cell formation. nerve damage.

septic shock symptoms

What occurs during viral uncoating? -The capsid breaks apart, releasing the viral genome. -The nucleic acid breaks apart, allowing for translation. -The viral proteins are synthesized. -The viral envelope is released.

the capsid breaks apart, releasing the viral genome

A persistent infection is one in which -host cells are gradually lysed. -host cells are transformed. -the virus remains in equilibrium with the host without causing a disease. -the disease process occurs gradually over a long period. -viral replication is unusually slow.

the disease process occurs gradually over a long period.

The ID50 is -a measure of pathogenicity. -the dose that will kill 50 percent of the test population. -the dose that will kill some of the test population. -the dose that will cause an infection in 50 percent of the test population. -the dose that will cause an infection in some of the test population.

the dose that will cause an infection in 50 percent of the test population.

How are prions different from other infectious agents? They cause neurological disease. They lack nucleic acid. They lack protein. They cannot replicate.

they lack nucleic acid

Ergot and aflatoxin are toxins sometimes found in grains contaminated with fungi. True False

true

Cytopathic effects are changes in host cells due to viral infections. helminthic infections. protozoan infections. bacterial infections. fungal infections.

viral infections

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

virulence factors