Nokea
The major role of the complement system is to work in conjunction with
- A. antibodies to lyse cells via the C8 and C9 components
- B. the major histocompatibility complex for cell recognition
- C. antibodies to opsonize cells
- D. the T-cell receptor for production of lymphokines
Correct Answer: A
Rationale: Rationale: The complement system is a group of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens. Choice A is correct because the C8 and C9 components of the complement system form the membrane attack complex which lyses cells. Choices B, C, and D are incorrect because the complement system primarily functions independently of the major histocompatibility complex, antibodies for opsonization, and T-cell receptor for lymphokine production.
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Which T cell type helps activate B cells?
- A. Cytotoxic T cells
- B. Helper T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: The correct answer is B: Helper T cells. Helper T cells play a crucial role in activating B cells by releasing cytokines that stimulate B cell proliferation and differentiation into plasma cells, which produce antibodies. Cytotoxic T cells (A) are involved in directly killing infected cells. Regulatory T cells (C) suppress immune responses. Memory T cells (D) are responsible for maintaining immunological memory for future responses. Thus, Helper T cells are the key cell type that helps activate B cells.
The hypervariable regions
- A. Are also called Complementary Determining Regions
- B. Are localized in the constant region of an antibody molecule
- C. Are not found in the secreted form of antibodies
- D. Are found only in heavy chains
Correct Answer: A
Rationale: Step 1: Hypervariable regions are responsible for antigen binding specificity.
Step 2: Complementary Determining Regions (CDRs) are the specific locations within the hypervariable regions.
Step 3: As CDRs are part of the hypervariable regions, choice A is correct.
Summary: Choices B, C, and D are incorrect because hypervariable regions are not in the constant region, are present in secreted antibodies, and are found in both heavy and light chains.
Normal mice injected with high doses of LPS die of septic shock. Mice resistant to LPS-induced septic shock have a mutation in which receptor?
- A. TLR4
- B. TLR5
- C. NOD1
- D. NOD2
Correct Answer: A
Rationale: Step 1: TLR4 is the receptor for lipopolysaccharide (LPS), a component of gram-negative bacteria.
Step 2: The question states that normal mice injected with high doses of LPS die, indicating TLR4 activation.
Step 3: Mutations in TLR4 can confer resistance to LPS-induced septic shock.
Step 4: Therefore, the correct answer is A: TLR4, as it is directly involved in recognizing LPS and triggering septic shock.
Summary: B: TLR5 does not specifically bind LPS. C: NOD1 and D: NOD2 are involved in intracellular recognition of bacterial components, not LPS.
What chemicals are responsible for the flavor and holes in Swiss cheese?
- A. lactate, oxygen
- B. propionic acid, carbon dioxide
- C. acetic acid, carbon dioxide
- D. ethanol, hydrogen
Correct Answer: B
Rationale: The correct answer is B: propionic acid, carbon dioxide. Propionic acid is produced by bacteria in Swiss cheese, contributing to its nutty flavor. The bacteria also produce carbon dioxide, which forms the characteristic holes. Lactate (A) is a byproduct of bacteria in cheese but not responsible for the flavor or holes. Acetic acid (C) is not commonly found in Swiss cheese. Ethanol (D) and hydrogen are not involved in the flavor or hole formation.
The nurse determines that a patient has long-term immunity against a disease. Which part of the immune system should the nurse recognize is responsible for this patient's long-term immunity?
- A. IgE
- B. IgG
- C. Mast cells
- D. Plasma cells
Correct Answer: B
Rationale: The correct answer is B: IgG. IgG is an immunoglobulin that provides long-term immunity by recognizing and neutralizing pathogens. It is produced by plasma cells in response to an infection, allowing the body to remember the pathogen and mount a quicker and more effective immune response upon re-exposure. IgE is involved in allergic reactions, not long-term immunity. Mast cells are involved in allergic responses and inflammation, not long-term immunity. Plasma cells produce antibodies, including IgG, but the plasma cells themselves are not responsible for long-term immunity.