Biol 228 - Chapter 15

8) The earliest smallpox vaccines were infected tissue rubbed into the skin of a healthy person. The recipient of such a vaccine usually developed a mild case of smallpox, recovered, and was immune thereafter. What is the most likely reason this vaccine did not kill more people? a. Skin is the wrong portal of entry for smallpox. b. The vaccine consisted of a mild form of the virus. c. Smallpox is normally transmitted by skin-to-skin contact. d. Smallpox is a virus. e. The virus mutated.

a. Skin is the wrong portal of entry for smallpox.

6)An encapsulated bacterium can be virulent because the capsule a. resists phagocytosis. b. is an endotoxin. c. destroys host tissues. d. kills host cells. e. has no effect; because many pathogens do not have capsules, capsules do not contribute to virulence.

a. resists phagocytosis.

4) All of the following are related to bacterial infection. Which would prevent all of the others? a. vaccination against fimbriae b. phagocytosis c. inhibition of phagocytic digestion d. destruction of adhesins e. alteration of cytoskeleton

a. vaccination against fimbriae

7) A drug that binds to mannose on human cells would prevent a. the entrance of Vibrio enterotoxin. b. the attachment of pathogenic E. coli. c. the action of botulinum toxin. d. streptococcal pneumonia. e. the action of diphtheria toxin.

b. the attachment of pathogenic E. coli.

10) Which of the following statements is true? a. The primary goal of a pathogen is to kill its host. b. Evolution selects for the most virulent pathogens. c. A successful pathogen doesn't kill its host before it is transmitted. d. A successful pathogen never kills its host.

c. A successful pathogen doesn't kill its host before it is transmitted.

5) The for ID50 Campylobacter sp. Is 500 cells; the ID50 for Cryptosporidium sp. Is 100 cells. Which of the following statements is false? a. Both microbes are pathogens. b. Both microbes produce infections in of the inoculated hosts. c. Campylobacter is more virulent than Cryptosporidium. d. Campylobacter and Cryptosporidium are equally virulent; they cause infections in the same number of test animals. e. Cryptosporidium infections are acquired more easily than Campylobacter infections.

c. Campylobacter is more virulent than Cryptosporidium.

9) Which of the following does not represent the same mechanism for avoiding host defenses as the others? a. Rabies virus attaches to the receptor for the neurotransmitter acetylcholine. b. Salmonella attaches to the receptor for epidermal growth factor. c. Lymphocryptovirus (mononucleosis) virus binds to the host receptor for complement protein. d. Surface protein genes in N. gonorrhoeae mutate frequently. e. none of the above

d. Surface protein genes in N. gonorrhoeae mutate frequently.

3) Which of the following is not a portal of entry for pathogens? a. mucous membranes of the respiratory tract b. mucous membranes of the digestive canal c. skin d. blood e. parenteral route

d. blood

Question 6:Which of these effects is most likely to occur if a pathogen enters the body by a portal of entry other than the preferred one? • Pathogens cannot enter by alternate routes. • A milder disease will result. • A more severe disease will result. • The exact same disease will result.

• A milder disease will result.

Question 15:A newly identified bacterial pathogen has been shown to cause disease in humans, disrupting the production of some proteins by interfering with the function of the endoplasmic reticulum of liver cells. Under specific growth conditions, this bacterial strain secretes a protein that appears to be responsible for the pathology of the disease. This protein is composed of two polypeptide chains, one of which binds to a receptor on the surface of liver cells, stimulating the uptake of the protein by endocytosis. Once inside the cell, the other polypeptide component interferes with the activity of ribosomes bound to the endoplasmic reticulum. This bacterial protein will most likely be classified as a/an __________. Hint: Exotoxins are proteins. • superantigen • bacterial kinase • invasin • A-B toxin • membrane-disrupting toxin

• A-B toxin

Question 9:Which of these substances are most important in the establishment of biofilms? Hint: Biofilms have the ability to attach to both living and nonliving surfaces. • hemolysins • Invasins • Siderophores • Adhesins • Exotoxins

• Adhesins

Question 7:Which of these organisms does NOT produce an enterotoxin? • Staphylococcus aureus • Vibrio cholerae • Shigella spp. • Clostridium botulinum

• Clostridium botulinum

Question 19:The pathogenicity of which of the following is NOT the result of lysogeny? Hint: Tetanospasmin is encoded by a plasmid gene. • Vibrio cholerae • Streptococcus pyogenes • Clostridium tetani • Clostridium botulinum • Corynebacterium diphtheriae

• Clostridium tetani

Question 9:Which of these is a cell wall component that contributes to invasiveness? • M protein • Hemolysin • Endotoxin • Coagulase

• M protein

Question 10:Which one of these bacterial proteins can take iron from human lactoferrin? • Protease • Kinase • Hyaluronidase • Siderophore

• Siderophore

Question 9:In some cases, viral infections of mammalian cells may __________. • cause cells to lose contact inhibition • cause cells to produce invasive enzymes such as hyaluronidase and collagenase • cause cells to produce endotoxin • cause cells to form capsules

• cause cells to lose contact inhibition

Question 10:Which one of these pairs is NOT correctly matched? Hint: Exoenzymes are specific to their substrate. • collagenase; breaks down connective tissue • coagulase; lyses fibrin clots • IgA protease; digest antibodies • leukocidin; lyses WBC membranes • siderophore; traps iron

• coagulase; lyses fibrin clots

1) The removal of plasmids reduces virulence in which of the following organisms? a. C. tetani b. E. coli c. S. enterica d. S. mutans e. C. botulinum

d. S. mutans

Question 12:Which of the following cell wall components do/does NOT contribute to virulence? • Fimbriae • M protein • Opa • mycolic acids • All of the listed choices contribute to virulence.

• All of the listed choices contribute to virulence.

Question 11:Which of the following toxins is NOT produced by a bacterium as a result of lysogenic conversion? • Endotoxin • diphtheria toxin • botulinum neurotoxin • staphylococcal enterotoxin

• Endotoxin

Question 4:You conduct a Limulus amebocyte lysate (LAL) assay on a sample of fluid that should be sterile. The result is positive. What does this indicate? • The fluid is not sterile. • Gram-positive bacteria are growing in the sample. • Gram-negative bacteria are growing. • Endotoxin is present.

• Endotoxin is present. ***Endotoxin can be present in sterile solutions because it is a molecule and not a living organism. Endotoxin may be present from dead or lysed bacterial cells.

Question 18:Which of these events leads to all of the others in a pyrogenic (fever) response? Hint: Fever-reducing drugs such as aspirin and acetaminophen inhibit the synthesis of prostaglandins. • The body's thermostat is set to a higher level, and fever occurs. • The hypothalamus releases prostaglandins. • IL-1 travels via the blood to the hypothalamus. • Endotoxin is released from the cell wall of gram-negative bacteria. • IL-1 is released by macrophages.

• Endotoxin is released from the cell wall of gram-negative bacteria.

Question 13:Which of these statements about toxoids is INCORRECT? • Diphtheria and tetanus can be prevented by toxoid vaccinations. • Toxoids stimulate the body to produce antitoxins without causing disease. • Gram-negative septic shock is commonly prevented by toxoids. • Exotoxins can be altered by heat or chemicals to form toxoids.

• Exotoxins can be altered by heat or chemicals to form toxoids.

Question 13:If bacteria attach to host tissue, they will cause disease. Hint: Consider the various types of symbiotic relationships. • True • False

• False ***Bacteria reside in us and on us. They can be symbiotic.

Question 12:If bacteria A and B have LD50 values of 109 and 1010, respectively, more cells of A than B will be needed to kill the host. Hint: In this example, LD50 refers to the number of bacteria required to kill 50% of the test population. • True • False

• False ***The lower the LD50, the less cells that are needed to establish and infection.

Question 11:The same disease symptoms result, regardless of how a particular microbe enters the body. Hint: Compare the symptoms of inhalation anthrax with those of cutaneous anthrax. • True • False

• False ***The route of entry can have drastic effects on the LD50 and the progression of a disease.

Question 14:Most host damage resulting from bacterial infection is the result of direct damage by the microbe. Hint: Consider the different ways that pathogens damage a host. • True • False

• False ***There are multiple ways for bacteria to damage a host for example nutrient depletion.

Question 14:Which one of these substances would NOT be produced at the same time as coagulase? • Fibrinolysin • hemolysin • Capsules • Fimbriae

• Fibrinolysin

Question 5:What cell structures does Neisseria gonorrhoeae use to attach and enter host epithelial cells? Hint: These structures bind to host cells along with the Opa protein before the microbe enters. • flagella • Fimbriae • capsules • M proteins • cell wall waxes

• Fimbriae

Question 3:Which of the following virulence factors is specifically involved in helping an organism to physically spread throughout the body? • siderophores • hemolysin • endotoxins • Hyaluronidase

• Hyaluronidase

Question 7:Which one of the following virulence factors contributes most to the spread of disease in the body? • siderophore production • Hemolysin • endotoxin production • Hyaluronidase

• Hyaluronidase

Question 5:Which of the following pairs is NOT correctly matched? Hint: Review the section "How Bacterial Pathogens Penetrate Host Defenses" in Chapter 14. • fibrinolysin; lyses fibrin clots • siderophore; traps iron • collagenase; breaks down connective tissue • leukocidin; lyses WBC membranes • IgA protease; lyses fibrin clots

• IgA protease; lyses fibrin clots

Question 7:Which of these statements is NOT true for bacterial capsules? Hint: The capsule can hinder phagocytosis. • Immune system antibodies are not produced against a capsule. • For Streptococcus pneumoniae, the encapsulated strain is more virulent. • Capsules related to virulence are produced by the causative agents of anthrax and bubonic plague. • Pathogenic and nonpathogenic bacteria can produce capsules. • The importance of the capsule to virulence for Streptococcus pneumoniae can be determined because there are strains both with and without the capsule.

• Immune system antibodies are not produced against a capsule.

Question 15:Which of these statements is true regarding portals of exit? • In most cases, a microbe uses the same portal for both entry and exit. • Polioviruses most often use the respiratory portal of exit. • The urinary tract is the most common portal of exit. • The portal of exit for tuberculosis is the skin.

• In most cases, a microbe uses the same portal for both entry and exit. ***Polioviruses use the gastrointestinal tract as a portal of exit. ***The gastrointestinal and respiratory tracts are the two most common portals of exit. ***The bacteria that cause tuberculosis exit through the respiratory tract.

Question 8:Capsules play a role in the virulence of all of the following EXCEPT __________. Hint: The cell wall waxes of acid-fast bacteria enhance their virulence by enabling them to resist digestion by phagocytes. • Haemophilus influenzae • Yersinia pestis • Bacillus anthracis • Mycobacterium tuberculosis • Klebsiella pneumoniae

• Mycobacterium tuberculosis

Question 18:Hepatitis B virus transmitted by a finger-stick device enters the host via which portal of entry? • Parenteral • Skin • Adherence • mucous membrane

• Parenteral

Question 4:Which would be the most UNLIKELY location to find adhesin molecules on a newly discovered bacterium? Hint: Adhesins allow microbes to attach to cell surface receptors. • Fimbriae • Capsule • Ribosomes • cell wall • glycocalyx

• Ribosomes

Question 8:Based on the following LD50 values, which microbe is the most virulent? Assume each bacterium enters through the appropriate portal of entry. • Shigella: 10 cells • Cryptosporidium: 50 cells • E. coli O157: 1000 cells • Vibrio cholerae: 108 cells

• Shigella: 10 cells ***LD50 describes the lethal dose for 50% of the inoculated hosts. Think about how that relates to the numbers of cells needed.

Question 19:Which of these substances does NOT protect a bacterium from phagocytosis? • capsule • M protein • Siderophore • Leucocidin

• Siderophore

Question 13:The LD50 of Vibrio choleraeis 108 cells through the oral route. If the bacterial cells are ingested with bicarbonate, the LD50 drops to 104. Which of these explanations is the most likely? Hint: Sodium bicarbonate will raise the pH of stomach contents. • Sodium bicarbonate decreases the virulence of Vibrio cholerae. • Stomach acid increases the virulence of Vibrio cholerae. • Vibrio cholerae makes toxins only in the presence of stomach acid. • Stomach acid decreases the virulence of Vibrio cholerae • Sodium bicarbonate inactivates Vibrio cholerae.

• Stomach acid decreases the virulence of Vibrio cholerae

Question 16:Which statement is NOT true of endotoxins? Hint: Toxoid vaccines, such as the vaccine for diphtheria and tetanus, are not available for prevention of symptoms associated with endotoxin production. • They are eliminated from the body as a result of antitoxin production. • They are more heat-resistant than exotoxins are. • They can induce chills, fever, aches, clotting, shock, and miscarriage. • Endotoxins are produced by Neisseria meningitidis and E. coli. • They can lyse amebocytes found in crab hemolymph.

• They are eliminated from the body as a result of antitoxin production.

Question 12:Which of the following statements is NOT true of A-B exotoxins? Hint: Exotoxins are proteins produced inside pathogenic bacteria. • The B portion of the toxin binds to surface receptors on host cells. • The A portion of the toxin is the active component. • They are produced only by gram-negative bacteria. • They consist of two polypeptide components. • Many exotoxins are A-B toxins.

• They are produced only by gram-negative bacteria.

Question 6:Which of the following is an accurate statement about A-B toxins? • They are proteins. • The A and B components must remain attached in order to exert their effects on the cell. • They are a type of endotoxin. • The A component binds to a receptor on the host cell.

• They are proteins. ***The A component must be attached to the B component to get into the cell. After entry, the two components detach, and the A portion exerts the effect on cell activity.

Question 14:Which statement is true of endotoxins? Hint: Endotoxins are part of the outer membrane (lipopolysaccharide layer) of gram-negative bacteria. • They are disease specific. • They are proteins. • They are released upon cell lysis. • They are produced only by gram-positive bacteria. • They increase blood pressure.

• They are released upon cell lysis.

Question 15:Accumulations of viral proteins and nucleic acids inside infected host cells are called inclusion bodies. Hint: Infections caused by the rabies virus are commonly diagnosed by the presence of Negri bodies in the cytoplasm of nerve cells. • True • False

• True ***Infections caused by viruses are commonly diagnosed by the presence of inclusion bodies.

Question 11:Which of these eukaryotic molecules/structures can be responsible for movement of bacteria within host cells? Hint: These components of the cytoskeleton help Shigella move within host cells. • actin molecules • cilia • pseudopods • invasins • flagella

• actin molecules

Question 20:Which type of organism produces the toxin responsible for paralytic shellfish poisoning? • a helminth • a protozoan • a bacterium • an alga

• an alga

Question 3:The ID50 for cutaneous anthrax due to Bacillus anthracis is 10 to 50 endospores, while the ID50 for inhalation anthrax is 10,000 to 20,000 endospores. This means that __________. Hint: The ID50 is a measure that represents the infectious dose for 50% of a given population. • both cutaneous and inhalation anthrax can easily be acquired • neither cutaneous nor inhalation anthrax can easily be acquired • cutaneous anthrax is easier to acquire than inhalation anthrax • inhalation anthrax is easier to acquire than cutaneous anthrax • not enough information is available to answer this question

• cutaneous anthrax is easier to acquire than inhalation anthrax

Question 8:Given the following LD50 values for Bacillus anthracis, through which portal of entry is it easiest to get anthrax? • cutaneous: 50 endospores • inhalation: 20,000 endospores • ingestion: 1 million endospores • All of the listed choices are equally easy portals of entry.

• cutaneous: 50 endospores ***Think about whether the LD50 should be high or low to indicate the easiest portal of entry for Bacillus anthracis.

Question 1:What is the general term for observable changes in cells that occur as a result of viral infection? • Syncytium • cytopathic effects • transformation bodies • inclusion bodies

• cytopathic effects

Question 2:Which of the following are possible locations for bacterial adhesins? • Fimbriae • Pili • Flagella • All of the listed choices are possible locations for bacterial adhesins.

• cytopathic effects

Question 20:Saxitoxin is produced by __________. Hint: Gonyaulax produces this neurotoxin, which can affect humans who consume shellfish contaminated during red tides. • protozoa • helminths • dinoflagellates • bacteria • fungi

• dinoflagellates

Question 5:Some organisms are capable of orchestrating alterations that are collectively termed antigenic variation. This allows an organism to __________. • enter the host's body through more than one portal of entry • rapidly move through the host's tissues • drastically decrease its ID50 • evade the host's immune system

• evade the host's immune system ***Antigenic variation refers to a situation in which an organism changes its service antigens.

Question 10:Which of the following diseases CANNOT be prevented by toxoids? • Botulism • Tetanus • Diphtheria • gram-negative septic shock

• gram-negative septic shock *** Toxoids can be used to immunize hosts against some bacterial exotoxins but cannot prevent this disease.

Question 16:Which one of these is NOT an example of pathogen entry via the parenteral route? • injection of the pathogen via a contaminated needle • entry through a break in the skin caused by a cut • injection via the bite of an infected insect • infection of a hair follicle right answer feedback:Infection of a hair follicle is not an example of the parenteral route because it does not involve a break in the skin.

• infection of a hair follicle Right answer: Infection of a hair follicle is not an example of the parenteral route because it does not involve a break in the skin. *** insect bite - This choice is an example of the parenteral route. *** skin caused by a cut - This choice is an example of the parenteral route. *** contaminated needle - This choice is an example of the parenteral route.

Question 17:Which of these viral cytopathic effects is most likely to be associated with the development of cancer? Hint: When viruses cause normal cells to become tumor cells, this is called viral transformation. • cell death • cell fusion • stimulation of interferon production • loss of contact inhibition • inclusion bodies

• loss of contact inhibition

Question 17:The symptoms of protozoan diseases are usually due to __________. • metabolic waste products • Capsules • Exotoxins • Endotoxins

• metabolic waste products

Question 2:If a patient has a deep tissue infection as the result of an animal bite on the arm, the portal of entry is described as the __________. Hint: Microbes that gain entry via injections are also said to enter via this portal. • parenteral route • gastrointestinal route • connective tissue • respiratory route • skin

• parenteral route

Question 1:Which disease is correctly matched with the common portal of entry? Hint: In some cases, disease symptoms may occur in regions of the body distant from the portal of entry. • chlamydia; skin • poliomyelitis; mucous membranes of gastrointestinal tract • influenza; mucous membranes of genitourinary tract • measles; parenteral route • hookworm; mucous membranes of genitourinary tract

• poliomyelitis; mucous membranes of gastrointestinal tract

Question 6:Which of these conditions would NOT affect the ability of Streptococcus mutans to attach to teeth? Hint: Streptococcus mutans attaches to teeth by way of polysaccharide coating outside the cell wall. • the inability to form dextran • the lack of a glycocalyx • the lack of the enzyme glucosyltransferase • the lack of sucrose • the absence of Actinomyces, a bacterium that can be part of dental plaque

• the absence of Actinomyces, a bacterium that can be part of dental plaque