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Microbiology Objective Questions { Microorganisms and Disease }

8. Both Mycobacterium tuberculosis and Streptococcus pneumoniae
A.are acquired by inhalation
B.have cell walls that contain a high content of mycolic acids
C.have polysaccharide capsules
D.stay in the lung and rarely, if ever, enter the bloodstream
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9. Cholera toxin is an A-B type toxin in which the B portions bind to a receptor on a host cell and the A portion enters the cell to cause
A.ADP ribosylation of adenylate cyclase that stops production of cAMP
B.ADP ribosylation of a G protein that locks it into an active form that stimulates adenylate cyclase to make cAMP
C.cleavage of rRNA that results in disruption of ribosome function
D.ADP ribosylation of guanylate cyclase that stimulates production of cGMP
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10.  Mucus helps in protecting against pathogens by
A.lowering the pH
B.facilitating the growth of normal flora
C.blocking access and attachment of pathogens to mucosal surfaces
D.sequestering Iron
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11. Type III secretion systems are used to inject "effector" proteins directly into a host cell. Salmonella uses a type III secretion system to help the pathogen to
A.survive the acid pH of the stomach
B.secrete LT (heat labile toxin) and ST (heat stable toxin) into the lumen of the intestine
C.survive within macrophages
D.activate T cells to proliferate and secrete cytokines
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12.  Which of these cytokines is also known under the name cachectin?
A.Interferon gamma
B.Interleukin 2
C.Tumor necrosis factor (TNF)
D.None of the above
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13. Which is not a major defense mechanism in the stomach?
A.Proteolytic enzymes
B.Low pH
C.Dense normal flora
D.All of these
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14. The agent responsible for causing mad cow disease is thought to be a
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