Nokea
What is the function of MHC molecules on antigen-presenting cells?
- A. Secreting cytokines
- B. Binding and destroying pathogens
- C. Displaying antigen fragments for T cell recognition
- D. Producing antibodies
Correct Answer: C
Rationale: The correct answer is C, displaying antigen fragments for T cell recognition. MHC molecules bind to antigen fragments and present them on the cell surface for T cells to recognize. This process is crucial for activating the immune response. Choice A is incorrect as MHC molecules do not secrete cytokines. Choice B is incorrect as MHC molecules do not directly destroy pathogens. Choice D is incorrect as MHC molecules do not produce antibodies; that is the function of B cells.
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During an adaptive immune response to a pathogen an important outcome of the clonal selection process is:
- A. An increase in the number of lymphocytes specific for the pathogen that activated the response
- B. Elimination of lymphocytes that are not specific for the pathogen that activated the response
- C. An increase in the number of antigen receptor specificities expressed by each lymphocyte
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A because during clonal selection, lymphocytes specific to the pathogen are activated, leading to their proliferation and differentiation into effector cells. This results in an increase in the number of lymphocytes specific for the pathogen, enhancing the immune response.
Choice B is incorrect because clonal selection does not involve the elimination of non-specific lymphocytes but rather the expansion of specific lymphocytes.
Choice C is also incorrect because clonal selection does not change the antigen receptor specificities expressed by lymphocytes but instead focuses on expanding the population of lymphocytes with receptors specific to the pathogen.
Therefore, the correct outcome of clonal selection is the increase in the number of lymphocytes specific for the pathogen that activated the response, making choice A the most accurate option.
Protease inhibitors interfere with
- A. Release of new viral particles from infected cells
- B. Processing of gp160
- C. Proviral stage
- D. Reverse transcription of viral RNA into DNA
Correct Answer: D
Rationale: Protease inhibitors interfere with the final step in HIV replication, which is the cleavage of the polyprotein into individual functional proteins. Inhibiting protease prevents the formation of mature infectious viral particles. This step occurs after reverse transcription of viral RNA into DNA, making choice D the correct answer. Choices A, B, and C are incorrect because protease inhibitors do not affect the release of new viral particles, processing of gp160, or the proviral stage of HIV replication.
Identify which statements are correct.
- A. All bacteria have peptidoglycan in their cell walls.
- B. All fungi have chitin in their cell walls.
- C. All algae have cellulose in their cell walls.
- D. All protozoans have protein in their cell walls.
Correct Answer: D
Rationale: The correct answer is D because protozoans do not have cell walls. They are single-celled organisms that lack a rigid cell wall. This distinguishes them from other microorganisms like bacteria, fungi, and algae which have distinct cell wall compositions such as peptidoglycan, chitin, and cellulose respectively. Choice A is incorrect as not all bacteria have peptidoglycan in their cell walls, some have other types of cell wall structures. Choice B is incorrect as not all fungi have chitin in their cell walls, some may have different components. Choice C is incorrect as not all algae have cellulose in their cell walls, there are variations in cell wall composition among different algal species.
In mice, mutations of which of the following genes cause the 'scurfy' phenotype (scaly skin and multiple autoimmune disorders)?
- A. FOXP3
- B. AIRE
- C. NFkB
- D. IRF
Correct Answer: A
Rationale: Rationale:
1. FOXP3 gene encodes a transcription factor crucial for regulatory T cells function.
2. Mutations in FOXP3 lead to dysfunctional regulatory T cells, causing autoimmune disorders.
3. Scurfy phenotype matches the symptoms of autoimmune disorders seen with FOXP3 mutations.
Summary:
- B (AIRE): AIRE mutations cause autoimmune polyendocrine syndrome, not scurfy phenotype.
- C (NFkB): NFkB is a transcription factor involved in immune response but not linked to scurfy phenotype.
- D (IRF): IRF is a regulator of interferon signaling, not directly associated with scurfy phenotype.
Priority Decision: The patient with advanced cancer is having difficulty controlling her pain. She says she is afraid she will become addicted to the opioids. What is the first thing the nurse should do for this patient?
- A. Administer a nonsteroidal antiinflammatory drug
- B. Assess the patient’s vital signs and behavior to determine the medication to use
- C. Have the patient keep a pain diary to better assess the patient’s potential addiction
- D. Obtain a detailed pain history including quality,location intensity duration and type of pain
Correct Answer: D
Rationale: A detailed pain history helps tailor pain management strategies and alleviates concerns about addiction.