Nokea
PRRs able to activate NFκB include
- A. TLR4
- B. NOD1
- C. NLRP3
- D. Both A and B
Correct Answer: D
Rationale: The correct answer is D because both TLR4 and NOD1 are pattern recognition receptors (PRRs) that can activate the NF-κB pathway. TLR4 recognizes bacterial lipopolysaccharides, while NOD1 detects bacterial peptidoglycan fragments. NLRP3, choice C, is an inflammasome receptor that activates caspase-1, not NF-κB. Therefore, choices A, B, and C are incorrect as they do not directly activate NF-κB like TLR4 and NOD1.
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Triggers for complement activation include
- A. Binding of opsonins, such as MBL, to microbes
- B. Direct recognition of microbes
- C. Formation of immune complexes
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all three choices are valid triggers for complement activation. A is correct as opsonins like MBL can bind to microbes and activate the complement system. B is correct as direct recognition of microbes can also trigger complement activation. C is correct as the formation of immune complexes can lead to complement activation through the classical pathway. Therefore, all of the above choices are triggers for complement activation.
What distinguishes NK cells from other lymphocytes?
- A. They are part of adaptive immunity
- B. They do not require prior antigen sensitization
- C. They directly produce antibodies
- D. They phagocytose pathogens
Correct Answer: B
Rationale: The correct answer is B because NK cells do not require prior antigen sensitization to recognize and attack infected cells. This distinguishes them from other lymphocytes, such as T and B cells, which are part of adaptive immunity and require prior exposure to specific antigens. NK cells are part of innate immunity and can directly recognize and kill infected or abnormal cells without prior activation. Choices A, C, and D are incorrect as NK cells are not part of adaptive immunity, do not directly produce antibodies, and do not phagocytose pathogens.
The nurse is reviewing the immune system prior to discussing the actions with a patient. What type of cell should the nurse identify that is involved in cell-mediated immunity and has a cytotoxic action on tumor cells?
- A. Lysosomes
- B. Memory cells
- C. Natural killer cells
- D. Histocompatibility cells
Correct Answer: C
Rationale: The correct answer is C: Natural killer cells. Natural killer cells are involved in cell-mediated immunity and have cytotoxic actions on tumor cells. They are part of the innate immune system and can directly kill infected or cancerous cells. Lysosomes (A) are organelles within cells that break down waste materials. Memory cells (B) are a type of immune cell that "remembers" previous infections to mount a faster response upon re-exposure. Histocompatibility cells (D) are involved in recognizing self from non-self in transplant situations, not in cytotoxic actions on tumor cells.
Which of the following are not examples of a terminal electron acceptor in anaerobic respiration?
- A. nitrate
- B. hydrogen sulfate
- C. iron hydroxide
- D. Hâ‚‚
Correct Answer: D
Rationale: The correct answer is D: H₂. In anaerobic respiration, H₂ can act as a terminal electron acceptor, so it is not an incorrect example. Nitrate, hydrogen sulfate, and iron hydroxide are all examples of terminal electron acceptors in anaerobic respiration. H₂ is commonly used in microbial processes as an electron donor, not as a terminal electron acceptor. This is because H₂ is typically oxidized to produce energy, rather than accepting electrons.
Dendritic cells play a role in:
- A. Costimulation of naïve T cells
- B. Processing of protein antigens to generate peptides
- C. Presentation of peptide-MHC complexes for recognition by T cell receptors
- D. All of the above
Correct Answer: D
Rationale: Dendritic cells play a crucial role in the immune system. Firstly, they provide costimulation to activate naïve T cells (A). Secondly, they process protein antigens into peptides for antigen presentation (B). Finally, dendritic cells present peptide-MHC complexes to T cell receptors for immune response activation (C). Therefore, the correct answer is D, as dendritic cells are involved in all these processes essential for initiating and regulating immune responses. Choices A, B, and C are incorrect as they are individual roles of dendritic cells and do not encompass the full range of functions that dendritic cells perform.