Mastering CH 15 & 16

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? a) More organisms of Staphylococcal bacteria must be ingested to cause infection, as compared to Shigella bacteria. b) Staphylococcal enterotoxin is the more lethal of the two toxins. c) Shiga toxin is more lethal than staphylococcal enterotoxin. d) 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? a) An individual contracts a hookworm infection as a result of walking around outside barefoot. b) An individual contracts hepatitis B from an accidental stick with a contaminated needle. c) An individual contracts a gastrointestinal infection by consuming contaminated water. d) An individual contracts gonorrhea as a result of unprotected sex.

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

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

Endotoxins are also known as a) cytokines. b) prostaglandins. c) interleukin-1. d) Lipid A.

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

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

Why is a release of endotoxin into the bloodstream potentially deadly? a) It causes necrosis of the liver. b) It results in dehydration of the patient. c) It can lower blood pressure and cause the patient to go into shock. d) 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) a) cytotoxin. b) superantigen. c) enterotoxin. d) neurotoxin.

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

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

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) superantigen b) cytotoxin. c) membrane disrupting toxin. d) enterotoxin.

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

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

Which of the following statements about innate immunity is true? a) Innate immunity involves specific recognition of microorganisms via a memory response. b) The innate immune response does not have a mechanism for detecting invading microorganisms. It is activated only in response to tissue damage or a signal from an infected cell. c) Innate immunity is present at birth. d) It involves the activity of B and T cells.

Mucous membranes are a part of a) the complement system. b) cell-mediated immunity. c) innate defense. d) adaptive defense.

According to the animation, B cells interact directly with a) helper T cells. b) the complement system. c) phagocytes. d) inflammation.

Which of the following defense systems would be involved in eliminating virally-infected cells? a) Phagocytosis b) Complement system c) T lymphocytes d) Humoral immunity

According to the animation, antibodies interact with which innate defenses? a) Phagocytosis b) Inflammation c) The complement system d) Phagocytosis and the complement system

Which cells directly attack abnormal cells in the body? a) Cytotoxic T cells b) Helper T cells c) B cells d) Phagocytes

If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers? a) monocytes b) lymphocytes c) basophils d) eosinophils

A response that is uniquely directed against pathogenic Bordetella pertussis would involve what component? a) Skin barrier b) Inflammation c) Antibodies d) The complement system

First line defenses have what aspect in common with each other? a) They involve the production of antibodies. b) They are physical barriers against invading pathogens. c) They recognize specific pathogens. d) They involve unique cells that attack invading pathogens.

Both the innate and adaptive defenses of the immune system work to prevent a) penetration by invading pathogens. b) colonization by pathogens. c) disease. d) the penetration and colonization by pathogens, and the diseases they cause.

If a new bacterial pathogen entered a human body through an accidental needle stick, the first cell that would try to kill the pathogen would likely be a) a cytotoxic T cell. b) an antibody-producing cell. c) a phagocyte.

Which of the following statements concerning phagocytosis is true? a) Adherence always requires opsonization. b) Phagocytes ingest microorganisms by using protein transporters that are specific to the bacteria. c) Bacteria are digested when the phagosome fuses with a lysosome. d) Phagocytes cannot ingest microorganisms unless they are coated with antibodies.

How is Streptococcus pneumoniae able to avoid destruction by a phagocyte? a) They prevent the fusion of the lysosome and phagosome. b) Their capsules make them "slippery" to phagocytes. c) They cause the lysosomes to empty their contents into the phagocyte, killing it.

Which microorganism requires the low pH inside a phagolysosome in order to reproduce? a) Streptococcus pneumoniae b) Streptococcus pyogenes c) Coxiella burnetii d) Haemophilus influenzae

Which of the following microorganisms use M protein to avoid destruction of a phagocyte? a) Coxiella burnetii b) Streptococcus pneumoniae c) Haemophilus influenzae d) Streptococcus pyogenes

Which of the following are best described as short chains of amino acids that are very stable and can have a variety of different antimicrobial activities, such as forming pores in bacterial plasma membranes and inhibiting cell wall synthesis? a) mannose-binding lectin b) antiviral proteins c) siderophores d) antimicrobial peptides