test 3
Chlamydia trachomatis is a bacterial STD that lives intracellularly within human host cells; what adaptive immune response would most likely prevail in this infection? A) cytotoxic T cells B) macrophages C) memory B cells D) plasma B cells E) defensins
A
Endotoxins are A) Associated with lipid A of the LPS layer. B) Secreted from the cell. C) Associated with gram-positive bacteria. D) Capsules. E) None of the above.
A
Natural killer cells target: A) infected cells that have lost MHC surface proteins B) bacterial cells that are coated with complement C) infected cells bound with antibody D) extracellular viruses E) All the above
A
Opsonization is a process whereby the innate and adaptive immune mechanisms work together: A) to phagocytize an invader B) to activate complement proteins C) for antibody secretion D) to destroy cancer cells E) during apoptosis
A
Regarding the neurotoxigenic disease caused by Clostridium tetani, which of the followingis not correct? A) It is typically a food-borne disease. B) It causes spasmic paralysis, i.e., continual muscle contractions that cannot stop. C) The causative agent produces endospores. D) It inhibits release of neurotransmitter from inhibitory neurons.
A
Staphylococcus aureus is a normal skin inhabitant that is harmless unless a break in the skin occurs; under these conditions, this bacterium can cause an infection. For this reason, S. aureus is referred to as a/an: ) opportunistic pathogen B) commensal C) parasite D) primary pathogen E) mutualist
A
The phenomenon of membrane ruffling carried out by Shigella and other bacteria, is depicted in the above photograph. Which is not true regarding this process? A) It is a type of phagocytosis, leading to death of the bacterium. B) It allows the bacteria to become an intracellular parasite. C) It is caused by rearrangement of the host cell cytoskeleton. D) It is preceded by the injection of several bacterial proteins into the host cell. E) It is due to a Type III secretion system present in the bacteria
A
Which of the following is a mostly nonproteinaceous, yet toxic, compound found in all Gram-negative bacteria? A) endotoxin B) exotoxin C) capsule D) type III secretion system E) none of the above
A
Which of the following pairs is mismatched? A) Interferons: secreted by eukaryotic cells; kills all pathogen types. B) Toll-like receptors: bind with bacterial surface molecules and release chemicals that trigger host defenses C) Defensins: form channels in bacterial cytoplasmic membranes, ultimately killing the cell D) Exogenous pyrogen: leads to an increase in the hypothalamic temperature set point E) Complement: more effective against Gram-negative cells
A
Which pair is not correctly matched? A) Hapten: by itself will produce the same effect as an epitope B) Threshold dose: elicits a strong immune response C) Immunogenic strength: protein > carbohydrate > DNA fragment D) Antigen-presenting cells: typically the way in which T cells see antigen E) Person with type B blood: has anti-A antibodies in serum
A
Your answer is CORRECT. Which of the following bacteria would you expect to cause the most severe blood disease in a susceptible host? A) a rapidly growing encapsulated bacteria B) a flagellated acidophile C) a biofilm-producing strain D) a piliated slow -growing Gram negative E) a halophilic psychrophile
A
All the following would be of benefit to extracellular pathogens, except A) the presence of a capsule B) ability to prevent the fusion of a phagosome and lysosome C) ability to prevent of opsonization D) ability to alter cell surface proteins via phase variation E) There are no exceptions; all are of benefit to extracellular pathogens.
B
Consider the data for two pathogens, agent 1 and agent 2 shown on the graph above. Which of the following is true regarding this data? A) Lower LD-50: Agent 2 B) More virulent pathogen: Agent 1 C) Less infectious pathogen: Agent 1 D) Higher LD-50: Agent 1 E) None of the above is true. Question 19
B
Herd immunity refers to everyone in a community becoming vaccinated to protect everyone against a particular disease. A) True B) False
B
Immunoprecipitation occurs when A) antigen is present in excess over antibody B) antigen and antibody ratios are approximately equal C) antibody is present in excess over antibody D) none of the above
B
The ability to lyse a phagosome or to prevent the fusion of a phagosome and lysosome would be of particular benefit to A) any pathogen. B) an intracellular pathogen. C) a macrophage. D) an extracellular pathogen. E) none of the above
B
The figure above depicts different infection cycles. Which label would indicate fomites? A) 4 B) 1 C) 2 D) the tick E) two of the above are correct
B
Which is false regarding sexually transmitted diseases (STDs)? A) Elementary body: infectious, but non-replicative form of Chlamydia B) Causative agent of syphilis is a Gram-negative diplococci, Treponema pallidum C) Diagnosis of gonorrhea: detection of bacteria in urethral discharge of males; females typically asymptomatic. D) Tertiary syphilis: advanced stage of untreated disease; characterized by dementia and/or heart problems E) None are false; all are true statements.
B
Which of the following would be considered an aspect of the adaptive immune response? A) interferons B) lymphocytes C) defensins D) natural killer cells E) all of the above
B
Which pair is not correctly matched? A) Hapten: not immunogenic by itself; requires a carrier protein B) Threshold dose: yields only a few B cells C) Immunogenic strength: protein > carbohydrate > DNA fragment D) Antigen-presenting cells: typically the way in which T cells see antigen E) Person with type B blood: has anti-A antibodies in serum
B
Which statement is false concerning the plague? A) Yersinia pestis is the bacterium responsible for this disease. B) Plague epidemics occur when infected mosquitos transfer the disease from human to human. C) The septicemic form of the plague is not the most infectious form of the disease. D) Plague is an example of a systemic infection. E) Part of the disease process by the plague bacteria is the formation of buboes, due to the enlargement of lymph nodes.
B
Which statement is not accurate regarding bacterial exotoxins? A) Exotoxins are protein toxins made & secreted by both Gram-positive and Gram-negative bacteria. B) Toxins with ADP ribosyltransferase activity all produce the same effect in affected individuals. C) Cholera toxin results in the loss of tremendous amounts of water from an affected individual. D) Exotoxins can cause disruption of cell membranes or inhibit eukaryotic ribosomes. E) Structurally, exotoxins possess a binding subunit and a subunit possessing the toxin activity.
B
A certain pathogen is not easily acquired by individuals, and has less than a 1% mortality rate among those unfortunate enough to acquire it. This pathogen is A) highly infectious and highly virulent. B) highly infectious and minimally virulent. C) minimally infectious and minimally virulent. D) minimally infectious and highly virulent. E) None of the above
C
All of the following statements are correct about microbial colonization of the human body except: A) The skin is a highly selective niche for certain microbes. B) Certain members of the oral microbiota can form biofilms on teeth causing cavities. C) The cardiovascular system possesses normal flora that are strictly commensal species. D) There are more anaerobes in the colon than aerobes. E) Intestinal bacteria are generally likely to be more acid tolerant.
C
Antigens coated with antibody can lead to all the following, except A) complement activation B) phagocytosis C) movement of neutrophils out of capillary blood vessels during inflammation D) agglutination E) neutralization of toxin or block adherence of bacteria to tissues
C
In immunology, the term clonal selection best refers to: A) the multiple types of cells needed to generate an antigenic specific response B) the ability of one B cell to produce antibodies to multiple antigens C) the ability of a specific B cell subset to proliferate upon exposure to a specific epitope D) the ability of memory B cells to induce a quick secondary antibody response E) the process of opsonizing antigen for rapid phagocytic degradation
C
The figure above depicts different infection cycles. Horizontal transmission is indicated by all the following EXCEPT: A) 1 B) 2 C) 6 D) A to B E) All the above indicate horizontal transmission
C
The figure above depicts different infection cycles. In regards to the mosquito-borne disease, what is the reservoir? A) the mosquito B) the girl in B C) the deer D) the tick E) the man in A
C
What adaptive immune response would most likely prevail in an infection by an extracellular pathogen? A) cytotoxic T cells B) macrophages C) B cells D) cytokines E) defensins
C
Which of the following could be categorized as an example of humoral immunity? A) macrophages B) T helper cells C) antimalaria antibodies D) cytotoxic T cells E) All are examples of humoral immunity
C
Which of the following is not a characteristic of T cells? A) They originate in bone marrow and mature in the thymus. B) Unlike B cells, certain T cells can directly kill infected host cells. C) When one is immunized with a vaccine, T cells are the primary responders in the body. D) They can secrete cytokines when activated. E) They recognize antigens associated with MHC proteins.
C
Which of the following is not associated with innate immunity? A) Interferon secretion B) Action of natural killer cells C) Activation of cytotoxic T cells D) Engulfment of bacteria by neutrophils E) All are associated with innate immunity
C
Which of the following nonspecific defense mechanisms does not need to be synthesized, and is already present in blood and available to respond immediately to infection? A) interferon B) defensin C) complement D) lysozyme E) prostaglandins
C
Which pathogen:description pair is not correct? A) Giardia: protozoal pathogen that is transmitted in feces (to water) as a cyst form. B) Neisseria meningitidis: capsulated, central nervous system pathogen capable of crossing the blood-brain barrier C) Mycobacterium tuberculosis: primary cause of pneumonia among humans D) Streptococcus pyogenes: primary cause of sore throats and also causes flesh-eating disease (i.e., necrotizing fasciitis) E) Streptococcus mutans: biofilm-forming pathogen that can cause endocarditis following a dental procedure
C
Why is antibiotic treatment not typically prescribed for staphylococcal food poisoning? A) The bacterium is a multidrug-resistant pathogen. B) No antibiotic is useful because its a mixed infection. C) No cells infect the body to cause the disease symptoms. D) The causative agent is a MRSA. E) None of the above.
C
A certain pathogen is not easily acquired by individuals, but has a 90% mortality rate among those unfortunate enough to acquire it. This pathogen is A) highly infectious and highly virulent. B) highly infectious and minimally virulent. C) minimally infectious and minimally virulent. D) minimally infectious and highly virulent. E) None of the above
D
Which of the following is not an integral part of the inflammatory process? A) dilation of blood vessels B) release of histamines, bradykinin, and prostaglandins C) extravasation D) decrease in the permeability of blood vessels in the area E) release of cytokines to attract cells of the immune system
D
Which of the following is not applicable to pathogenic strains of Staphylococcus aureus? A) It is a primary cause of skin infections. B) Many strains are resistant to conventional penicillin-like antibiotics. C) It can cause gastroenteritis due to food poisoning. D) It is a common cause of sore throats. E) Toxic shock syndrome is attributable to this bacterium.
D
Which of the following is not associated with innate immunity? A) Lysozyme in saliva B) Action of natural killer cells C) Macrophage engulfment of bacteria D) Secondary antibody response E) Alternative complement pathway
D
Which pathogen:description pair is not correct? A) Giardia: protozoal pathogen that is transmitted in feces (to water) as a cyst form. B) Neisseria meningitidis: capsulated, central nervous system pathogen capable of crossing the blood-brain barrier C) Mycobacterium tuberculosis: slow-growing, acid fast bacterium that causes a chronic respiratory disease D) Streptococcus pneumoniae: primary cause of sore throats and also causes flesh-eating disease (i.e., necrotizing fasciitis) E) Streptococcus mutans: biofilm-forming pathogen that can cause endocarditis following a dental procedure
D
BONUS Commensals do not need virulence factors to survive on their host because: A) they are well adapted for their specific niche B) they do not breach the host barriers and immune system C) they do not normally cause disease D) two of A, B, and C are correct E) A, B, and C are all correct
E
BONUS Which of the following bacterial types can become an intracellular pathogen (either facultative or obligate) during the course of an infection? A) Chlamydia B) Salmonella C) Shigella D) Mycobacterium tuberculosis E) All the above
E
BONUS Which of the following bacterial types does not become an intracellular pathogen (either facultative or obligate)during the course of an infection? A) Chlamydia B) Salmonella C) Shigella D) Mycobacterium tuberculosis E) All the above can become an intracellular pathogen.
E
Natural killer cells target: A) infected cells that have lost MHC surface proteins B) bacterial cells that are coated with complement C) infected cells bound with antibody D) cancerous cells E) Two of the above are correct
E
The figure above depicts an antibody. For the labeled area, which pair below is correctly matched? (e is referring to the Fc stem region that includes both c and) A) Antigen-binding site: c and d B) Your IgG antibodies are all similar in these areas: a and b C) Can attach to a host cell (e.g., a macrophage): a and b D) Your IgM antibodies are all different in these areas: c and d E) None are matched correctly.
E
Which of the following does not contribute to the virulence of a pathogen? A) Toxins B) Capsule C) Fimbriae/pili D) Numbers of microorganisms that gain access to a host E) All contribute to the virulence of a pathogen
E
Which of the following is not a characteristic of B cells? A) Memory B cells are responsible for the enhanced secondary antibody response B) They have antibodies on their surfaces. C) Plasma B cells form and secrete antibodies. D) They originate in bone marrow. E) B cells can directly kill pathogenic microbes.
E
Which of the following is not an integral part of the inflammatory process? A) dilation of blood vessels B) release of histamines, bradykinin, and prostaglandins C) release of cytokines to attract cells of the immune system D) extravasation E) antibody synthesis
E
Which of the following is not correct about malaria? A) Plasmodium species are the causative agents of malaria; they are protozoans. B) Plasmodium parasites avoid the immune system by constantly changing cell surface proteins. C) Malaria is an infection of the cardiovascular system. D) The Anopheles mosquito is the vector for transmission of malaria. E) All are correct statements.
E
Which of the following pathogens does not cause gastroenteritis/diarrhea? A) Escherichia coli Ol57:H7 B) Rotavirus C) Shigella D) Giardia E) All cause gastroenteritis/diarrhea.
E
Which statement is not accurate regarding bacterial exotoxins? A) Exotoxins are protein toxins made & secreted by both Gram-positive and Gram-negative bacteria. B) Toxins with ADP ribosyltransferase activity produce different effects depending on the toxin type. C) The cholera toxin gene of pathogenic Vibrio cholera strains is acquired from a bacterial virus (i.e., bacteriophage). D) Exotoxins can be superantigens or proteases. E) All are accurate statements.
E