Chapter 15 Homework

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

When would endotoxins be released from a bacterial cell?

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

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

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

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

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

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. enterotoxin. membrane disrupting toxin. cytotoxin.

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

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

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

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

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

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. Shiga toxin is more lethal than staphylococcal enterotoxin. 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.

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 a hookworm infection as a result of walking around outside barefoot. An individual contracts a gastrointestinal infection by consuming contaminated water. An individual contracts gonorrhea as a result of unprotected sex.

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

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

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

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

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

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

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

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

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

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

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

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

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

Which statement regarding endotoxins is true? 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.

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

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

Which of the following statements about lysogenic conversion is true? Exotoxin production by bacteria is frequently the result of a lysogenic infection. Endotoxin production by bacteria is frequently the result of a lysogenic infection. 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.

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

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

According to your Concept Map, which of the following organisms exhibits antigenic variation? Mycobacterium tuberculosis N. gonorrheae S. pneumoniae H. influenzae

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

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

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

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

How do fibrinolysins enhance a pathogen's virulence? They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin. 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.

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

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

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

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 produce an exaggerated response, distracting it from the actual pathogen. They cause the immune system to destroy IgA antibodies. They cause the immune system to turn on itself.

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

How are immune cells able to detect foreign pathogens? 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 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.

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

How does the protozoan Trypanosoma evade detection by the immune system? It can resist oxidation inside macrophages. It prevents phagosome-lysosome fusion. 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.

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

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

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

How do Shigella cells move between host cells? They are secreted directly into the epithelial cells from the M cells. They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another. They lyse the M cell, releasing thousands of new cells to infect other host cells. They are secreted by phagocytes.

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

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

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

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

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

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