Nokea
Which of the following is a characteristic of CTL?
- A. They kill target cells through recognition of peptide-MHC class I complexes
- B. They die in the process of killing a target cell
- C. They can kill target cells by activating complement
- D. They carry out their effector function in secondary lymphoid tissues
Correct Answer: A
Rationale: The correct answer is A because cytotoxic T lymphocytes (CTLs) kill target cells by recognizing specific peptide antigens presented on major histocompatibility complex (MHC) class I molecules. This recognition triggers the CTLs to release cytotoxic molecules that induce apoptosis in the target cells. Choice B is incorrect because CTLs do not die in the process of killing target cells; they survive to continue their immune response. Choice C is incorrect as CTLs do not kill target cells by activating complement, but rather through direct cell-cell contact. Choice D is incorrect because CTLs carry out their effector function in peripheral tissues where they encounter target cells, not specifically in secondary lymphoid tissues.
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The nurse is studying hypersensitivity reactions. Which reactions are correctly matched with their hypersensitivity types? (Select one that does not apply.)
- A. Type I—examples include hay fever and anaphylaxis.
- B. Type II—mediated by action of immunoglobulin M (IgM).
- C. Type III—immune complex deposits in blood vessel walls.
- D. Type IV—examples are poison ivy and transplant rejection.
Correct Answer: B
Rationale: The correct answer is B because Type II hypersensitivity reactions are mediated by the action of immunoglobulin G (IgG) or immunoglobulin M (IgM), not just IgM alone. IgG or IgM antibodies target specific antigens on the surface of cells or tissues, leading to cell destruction. In contrast, Type I hypersensitivity reactions (choice A) involve immediate IgE-mediated responses to allergens like hay fever and anaphylaxis. Type III reactions (choice C) are characterized by immune complex deposition in tissues, not blood vessel walls. Type IV reactions (choice D) are delayed hypersensitivity reactions involving T cell-mediated responses, such as poison ivy contact dermatitis and transplant rejection.
Why do opportunistic diseases develop in an individual with AIDS?
- A. They are side effects of drug treatment of AIDS.
- B. They are sexually transmitted to individuals during exposure to HIV.
- C. They are characteristic in individuals with stimulated B and T lymphocytes.
- D. These infections or tumors occur in a person with an incompetent immune system.
Correct Answer: D
Rationale: Opportunistic diseases arise because the immune system is severely compromised in individuals with AIDS, making them susceptible to infections and cancers they would otherwise resist.
The way in which some organism supplies some other organism with food and energy known as
- A. Food chains
- B. Food Network
- C. Pyramid of power
- D. levels of nutrition
Correct Answer: A
Rationale: The correct answer is A: Food chains. A food chain depicts the flow of energy and nutrients from one organism to another in an ecosystem. It shows how energy is transferred from producers to consumers. Food network (B) is a more complex and interconnected system than a simple linear chain. Pyramid of power (C) represents the energy flow in an ecosystem, not the transfer of food. Levels of nutrition (D) is not a term commonly used to describe how organisms transfer food and energy.
Secondary lymphoid tissues are where:
- A. naïve lymphocytes become activated
- B. VDI gene rearrangement occurs
- C. Somatic hypermutation occurs
- D. Two of these options are correct
Correct Answer: D
Rationale: The correct answer is D because secondary lymphoid tissues are where both A and C processes occur. Naïve lymphocytes become activated in secondary lymphoid tissues through interactions with antigens, leading to their differentiation into effector cells. Somatic hypermutation also occurs in secondary lymphoid tissues, specifically in germinal centers of lymph nodes, leading to the generation of high-affinity antibodies. Option B, VDI gene rearrangement, does not occur in secondary lymphoid tissues; it is a process that happens in the primary lymphoid organs (bone marrow and thymus) during the development of lymphocytes. Thus, options A and C are correct, making the correct answer D.
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.