Nokea
Which cell type bridges innate and adaptive immunity?
- A. NK cells
- B. Dendritic cells
- C. Plasma cells
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: Dendritic cells. Dendritic cells bridge innate and adaptive immunity by capturing antigens, processing them, and presenting them to T cells to initiate adaptive immune responses. NK cells (A) are part of innate immunity, while plasma cells (C) produce antibodies in adaptive immunity. Mast cells (D) are involved in allergic responses, not bridging innate and adaptive immunity.
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Which of the following is NOT an outcome of complement activation:
- A. Increased recruitment of inflammatory cells
- B. Opsonization of pathogens
- C. Lysis of pathogens
- D. Increased migration of dendritic cells from tissues to lymph nodes
Correct Answer: D
Rationale: The correct answer is D: Increased migration of dendritic cells from tissues to lymph nodes. Complement activation does not directly lead to the migration of dendritic cells. Complement activation can lead to increased recruitment of inflammatory cells (A), opsonization of pathogens (B), and lysis of pathogens (C). Dendritic cells typically migrate to lymph nodes to present antigens to T cells, but this process is not directly mediated by complement activation.
What describes the occurrence of a type IV or delayed hypersensitivity transplant reaction?
- A. Antigen links with specific IgE antibodies bound to mast cells or basophils releasing chemical mediators
- B. Cellular lysis or phagocytosis through complement activation following antigen-antibody binding on cell surfaces
- C. Sensitized T lymphocytes attack antigens or release cytokines that attract macrophages that cause tissue damage
- D. Antigens combined with IgG and IgM too small to be removed by mononuclear phagocytic system deposit in tissue and cause fixation of complement
Correct Answer: C
Rationale: Type IV hypersensitivity involves sensitized T lymphocytes attacking antigens or releasing cytokines that recruit macrophages, causing tissue damage.
In a client with AIDS,a CD4 cell count above ______ mm³ would indicate that antiretroviral therapy is being effective.
- A. 250
- B. 1000
- C. 500
- D. 275
Correct Answer: C
Rationale: A CD4 count above 500 mm³ indicates a strong immune response and effective antiretroviral therapy.
What is hypersensitivity in immunology?
- A. An excessive or inappropriate immune response causing tissue damage
- B. The body's inability to mount an immune response
- C. A low-level immune reaction to antigens
- D. A mechanism for faster immune response during infections
Correct Answer: A
Rationale: Step-by-step rationale:
1. Hypersensitivity in immunology refers to an exaggerated or inappropriate immune response.
2. This excessive response can lead to tissue damage and various immune-mediated conditions.
3. Choice A accurately describes this concept.
Summary:
- Choice A is correct as it accurately defines hypersensitivity.
- Choice B is incorrect as hypersensitivity involves an exaggerated immune response, not an inability to mount one.
- Choice C is incorrect as hypersensitivity is not a low-level immune reaction.
- Choice D is incorrect as hypersensitivity is not a mechanism for faster immune response, but rather an overreaction.
Which enzyme catalyzes the addition of deoxynucleotides to the 3'OH ends of DNA molecules?
- A. Phosphohydrolase
- B. T4 DNA ligase
- C. Terminal deoxynucleotidyl transferase
- D. DNA endonuclease
Correct Answer: C
Rationale: The correct answer is C: Terminal deoxynucleotidyl transferase (TdT). TdT catalyzes the addition of deoxynucleotides to the 3'OH ends of DNA molecules. It does so by adding nucleotides in a template-independent manner, making it crucial for generating diversity in immune cell receptor genes.
A: Phosphohydrolase - This enzyme is not involved in adding deoxynucleotides to DNA ends.
B: T4 DNA ligase - This enzyme catalyzes the joining of DNA fragments, not the addition of deoxynucleotides.
D: DNA endonuclease - This enzyme cleaves DNA internally, not involved in adding deoxynucleotides to DNA ends.