Microorganisms and Disease – Section 1

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

Correct Answer: C. survive within macrophages

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

Correct Answer: C. Tumor necrosis factor (TNF)

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

Correct Answer: C. Dense normal flora

14. The agent responsible for causing mad cow disease is thought to be a

A. fungus
B. protozoan
C. prion
D. virus

Correct Answer: C. prion

15. The “A” subunit of diphtheria toxin

A. binds host cell receptors found on heart cells
B. cause ADP ribosylation of a factor involved in protein synthesis
C. forms cAMP that leads to fluid accumulation
D. lysis macrophages with the release of cytokines

Correct Answer: B. cause ADP ribosylation of a factor involved in protein synthesis

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