Questions and answers for exam Preparation

MCQs

Total Questions : 304 | Page 29 of 31 pages

Question 281. . Mucus helps in protecting against pathogens by

lowering the pH
facilitating the growth of normal flora
blocking access and attachment of pathogens to mucosal surfaces
sequestering Iron

Discuss Question

Answer: Option C. -> blocking access and attachment of pathogens to mucosal surfaces

Question 282. 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

ADP ribosylation of adenylate cyclase that stops production of cAMP
ADP ribosylation of a G protein that locks it into an active form that stimulates adenylate cyclase to make cAMP
cleavage of rRNA that results in disruption of ribosome function
ADP ribosylation of guanylate cyclase that stimulates production of cGMP

Discuss Question

Answer: Option B. -> ADP ribosylation of a G protein that locks it into an active form that stimulates adenylate cyclase to make cAMP

Question 283. .
Which of these cytokines is also known under the name cachectin?

Interferon gamma
Interleukin 2
Tumor necrosis factor (TNF)
None of the above

Discuss Question

Answer: Option C. -> Tumor necrosis factor (TNF)

Question 284. . 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

survive the acid pH of the stomach
secrete LT (heat labile toxin) and ST (heat stable toxin) into the lumen of the intestine
survive within macrophages
activate T cells to proliferate and secrete cytokines

Discuss Question

Answer: Option C. -> survive within macrophages

Question 285. . The agent responsible for causing mad cow disease is thought to be a

fungus
protozoan
prion
virus

Discuss Question

Answer: Option C. -> prion

Question 286. . Which is not a major defense mechanism in the stomach?

Proteolytic enzymes
Low pH
Dense normal flora
All of these

Discuss Question

Answer: Option C. -> Dense normal flora

Question 287. . The "A" subunit of diphtheria toxin

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

Discuss Question

Answer: Option B. -> cause ADP ribosylation of a factor involved in protein synthesis

Question 288. . Which of the following statements is not true regarding Mycobacterium tuberculosis and/or the disease it causes?

The pathogen contains mycolic acid in its cell wall
The pathogen can live inside macrophages
Antibodies to the pathogen are protective
None of these

Discuss Question

Answer: Option C. -> Antibodies to the pathogen are protective

Question 289. . Prontosil is

an effective antibacterial when used in animals
an effective antibacterial when used in in-vitro cultures
an effective antibacterial both in animals as well as in in-vitro cultures
not used as an antibacterial agent

Discuss Question

Answer: Option C. -> an effective antibacterial both in animals as well as in in-vitro cultures

Question 290. . Immunization with which of the following toxoid induces high titer serum antibody, but does not protect from the corresponding disease?