Nokea
Which of the following is correct with respect to measles:
- A. Outbreaks of the disease have recently occurred in developed countries as a consequence of decreased vaccination rates
- B. The disease has been eradicated globally
- C. There is no effective vaccine for this disease
- D. The disease is now easily treated and has no known long-term effects
Correct Answer: A
Rationale: Rationale for Choice A: Outbreaks of measles in developed countries are due to decreased vaccination rates, leading to lower herd immunity. This is supported by data showing increasing cases in countries with vaccine hesitancy. Other choices are incorrect because B is false - measles has not been eradicated globally, C is false - there is an effective vaccine for measles, and D is false - measles can lead to severe complications and long-term effects, especially in unvaccinated individuals.
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What type of cells do natural killer (NK) cells target?
- A. Bacterial cells
- B. Virus-infected and cancerous cells
- C. Plasma cells
- D. Self-antigens
Correct Answer: B
Rationale: Natural killer (NK) cells target virus-infected and cancerous cells because they have the ability to recognize abnormal cells through activating receptors. These cells can identify changes in surface markers associated with viral infection or cancer, leading to their destruction. NK cells do not target bacterial cells (choice A), plasma cells (choice C), or self-antigens (choice D) as these are not typically recognized as threats by the immune system. NK cells play a crucial role in immune surveillance against abnormal cells, making choice B the correct answer.
The Calvin cycle:
- A. is a C5 pathway
- B. is used by all photoautotrophic microorganisms
- C. is a C4 pathway
- D. is a dark reaction
Correct Answer: D
Rationale: The Calvin cycle is a series of biochemical reactions that take place in the stroma of chloroplasts during photosynthesis. It occurs in the dark phase (without direct light requirement), making choice D correct. Choice A is incorrect because the Calvin cycle is a C3 pathway, not C5. Choice B is incorrect because not all photoautotrophic microorganisms use the Calvin cycle; some use alternative pathways. Choice C is incorrect because C4 pathway is a different photosynthetic pathway that occurs in certain plants to minimize photorespiration.
During data collection, the nurse learns the patient is allergic to shellfish. Which precautions should be implemented during the patient's hospitalization?
- A. The patient should be placed in a private room.
- B. The kitchen should use dedicated equipment for all of the patient's food preparation.
- C. Iodine-based skin preparations should be replaced with different bactericidal cleansers.
- D. The patient's allergy should be noted on the medical record and communicated clearly to all caretakers.
Correct Answer: D
Rationale: Rationale:
1. The correct answer is D because it addresses the essential action of noting the patient's allergy on the medical record and communicating it to all caretakers to prevent inadvertent exposure.
2. Choice A is not necessary unless the patient's allergy poses an infection control risk that warrants isolation.
3. Choice B is excessive and not required as long as cross-contamination is prevented during food preparation.
4. Choice C is unrelated to the patient's shellfish allergy and not a standard precaution in this scenario.
Which complement pathway is triggered by mannose-binding lectin (MBL)?
- A. Alternative pathway
- B. Classical pathway
- C. Lectin pathway
- D. Terminal pathway
Correct Answer: C
Rationale: The correct answer is C, Lectin pathway. MBL recognizes pathogen-associated molecular patterns containing mannose, initiating the lectin pathway. MBL binds to mannose on microbial surfaces, activating MBL-associated serine proteases, leading to the formation of the C3 convertase. This triggers the rest of the complement cascade.
A: Alternative pathway is triggered by spontaneous hydrolysis of C3, not by MBL.
B: Classical pathway is activated by antigen-antibody complexes, not MBL.
D: Terminal pathway (also known as the membrane attack complex) is the final step of all complement pathways, not specifically triggered by MBL.
Which TLR is primarily responsible for recognizing lipopolysaccharide (LPS)?
- A. TLR2
- B. TLR4
- C. TLR5
- D. TLR9
Correct Answer: B
Rationale: The correct answer is B: TLR4. TLR4 is primarily responsible for recognizing lipopolysaccharide (LPS) found in the outer membrane of Gram-negative bacteria. It forms a complex with MD-2 and CD14 to trigger downstream signaling pathways. TLR2 recognizes other microbial components such as lipoproteins. TLR5 recognizes flagellin, a component of bacterial flagella. TLR9 recognizes unmethylated CpG DNA motifs. Therefore, TLR4 is specifically involved in detecting LPS, making it the correct answer in this scenario.