Nokea
The three antibiotic-resistant bacteria that are of most current concern in North America are ____________________, ____________________, and ____________________.
- A. Methicillin-resistant Staphylococcus aureus (MRSA)
- B. Carbapenem-resistant Enterobacteriaceae (CRE)
- C. Vancomycin-resistant Enterococcus (VRE)
- D. All of the above
Correct Answer: D
Rationale: The correct answer is all of the above. MRSA, CRE, and VRE are among the most concerning antibiotic-resistant bacteria in North America due to their prevalence and difficulty in treatment.
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What are characteristics of the phosphate buffer system (select all that apply)?
- A. Neutralizes a strong base to a weak base and water
- B. Resultant sodium biphosphate is eliminated by kidneys
- C. Free acid radicals dissociate into H+ and CO2,buffering excess base
- D. Neutralizes a strong acid to yield sodium biphosphate,a weak acid and salt
Correct Answer: B
Rationale: Phosphate buffers neutralize strong bases/acid, form sodium biphosphate, and eliminate it through the kidneys.
Which compounds produced by microorganisms can cause fever in humans and can withstand autoclaving?
- A. endotoxin
- B. Lipid A
- C. lipopolysaccharide
- D. peptidoglycan
Correct Answer: D
Rationale: The correct answer is D, peptidoglycan. Peptidoglycan is a component of bacterial cell walls that can trigger fever in humans. It is a sturdy molecule that can withstand autoclaving.
A: Endotoxin is a component of the outer membrane of Gram-negative bacteria, not resistant to autoclaving.
B: Lipid A is the toxic component of endotoxin, not resistant to autoclaving.
C: Lipopolysaccharide is the major component of the outer membrane of Gram-negative bacteria, not resistant to autoclaving.
TLR-3 detects viruses found in:
- A. Cytosol
- B. Extracellular space
- C. Endosomes
- D. All of the above
Correct Answer: C
Rationale: TLR-3 detects viruses in endosomes. When a virus enters a host cell, it is often engulfed into endosomes. TLR-3 recognizes viral RNA within endosomes and triggers an immune response. Choices A and B are incorrect because TLR-3 does not detect viruses in the cytosol or extracellular space. Choice D is incorrect because TLR-3 specifically functions in endosomes to detect viral RNA.
What is the main limitation of innate immunity compared to adaptive immunity?
- A. It cannot produce cytokines
- B. It lacks memory and specificity
- C. It does not include physical barriers
- D. It cannot activate complement
Correct Answer: B
Rationale: The main limitation of innate immunity compared to adaptive immunity is that innate immunity lacks memory and specificity. This means that innate immune responses do not improve upon repeated exposure to the same pathogen and cannot target specific antigens efficiently. Adaptive immunity, on the other hand, can remember previous encounters with pathogens and mount targeted responses. Choices A, C, and D are incorrect because innate immunity can produce cytokines, includes physical barriers like skin and mucous membranes, and can activate complement as part of its defense mechanisms.
According to the hygiene hypothesis, which of the following factors protect us from developing immune diseases?
- A. Small family size
- B. Good sanitation
- C. Low antibiotic use
- D. Living in "westernized" countries
Correct Answer: C
Rationale: The correct answer is C: Low antibiotic use. The hygiene hypothesis suggests that reduced exposure to infections, which can happen with low antibiotic use, can lead to an increased risk of immune diseases. Antibiotics can disrupt the balance of gut microbiota, which plays a crucial role in immune system development. A: Small family size may not necessarily protect against immune diseases as it does not directly relate to exposure to infections. B: Good sanitation can reduce the spread of infections but may not necessarily protect against immune diseases. D: Living in "westernized" countries is a broad factor and does not directly address the impact of low antibiotic use on immune diseases.