Nokea
What is the structural composition of an antibody?
- A. Two heavy chains and two light chains
- B. Three heavy chains and one light chain
- C. Two heavy chains and three light chains
- D. Four heavy chains
Correct Answer: A
Rationale: The correct answer is A: Two heavy chains and two light chains. Antibodies are composed of two identical heavy chains and two identical light chains. Heavy chains provide structural support and effector functions, while light chains contribute to antigen binding. Choice B is incorrect as antibodies do not have three heavy chains. Choice C is incorrect as antibodies do not have three light chains. Choice D is incorrect as antibodies do not have four heavy chains.
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A main cytokine produced by CD4+ TH1 cells is
- A. IL-4
- B. IL-10
- C. IL-5
- D. IFN-γ
Correct Answer: D
Rationale: The correct answer is D: IFN-γ. CD4+ TH1 cells are known to primarily produce interferon-gamma (IFN-γ). This cytokine plays a crucial role in promoting cell-mediated immunity and enhancing the activity of macrophages. IL-4 (choice A) is produced by CD4+ TH2 cells and promotes humoral immunity. IL-10 (choice B) is an anti-inflammatory cytokine produced by various immune cells. IL-5 (choice C) is predominantly produced by CD4+ TH2 cells and is involved in eosinophil activation. Therefore, the main cytokine produced by CD4+ TH1 cells is IFN-γ, making choice D the correct answer.
Which of the following is not a function of the immune system?
- A. Protecting the body from foreign substances
- B. Producing hormones
- C. Repairing damaged tissues
- D. All of the above are functions of the immune system
Correct Answer: B
Rationale: The correct answer is B: Producing hormones. The immune system's main functions are to protect the body from foreign substances and repair damaged tissues. Producing hormones is not a direct function of the immune system. Hormone production is primarily regulated by the endocrine system, not the immune system. Therefore, option B is not a function of the immune system. Options A and C are incorrect as protecting the body from foreign substances and repairing damaged tissues are essential roles of the immune system. Option D is incorrect because not all functions listed are actually performed by the immune system.
What was atypical about the 2009 H1N1 pandemic?
- A. It emerged entirely as an assortment of human strains, while typical pandemics are caused by newly generated animal strains
- B. It was a newly assorted virus unrelated to the human strains that were circulating worldwide in 2009
- C. It was a variant of 1918 H1N1 that is still circulating in pigs
- D. It did not affect the very young, an age group typically struck by flu viruses
Correct Answer: B
Rationale: The correct answer is B because the 2009 H1N1 pandemic was caused by a newly assorted virus unrelated to existing human strains. This is atypical as typical pandemics are caused by animal strains. Option A is incorrect because the 2009 H1N1 pandemic did not emerge entirely as an assortment of human strains. Option C is incorrect as the 2009 H1N1 virus was not a variant of the 1918 H1N1 strain circulating in pigs. Option D is incorrect because the 2009 H1N1 pandemic did affect individuals across all age groups, including the very young.
What is the primary cause of anaphylaxis?
- A. Immune complex deposition
- B. Systemic release of vasoactive mediators
- C. Localized mast cell degranulation
- D. T cell activation
Correct Answer: B
Rationale: The correct answer is B: Systemic release of vasoactive mediators. Anaphylaxis is a severe allergic reaction that is primarily caused by the systemic release of vasoactive mediators such as histamine, prostaglandins, and leukotrienes from mast cells and basophils. These mediators lead to widespread vasodilation, increased vascular permeability, bronchoconstriction, and systemic hypotension, resulting in the characteristic symptoms of anaphylaxis.
Choice A (Immune complex deposition) is incorrect because anaphylaxis is not caused by the deposition of immune complexes but rather by the immediate hypersensitivity reaction.
Choice C (Localized mast cell degranulation) is incorrect because anaphylaxis involves systemic mast cell degranulation leading to widespread effects throughout the body, not just localized reactions.
Choice D (T cell activation) is incorrect because anaphylaxis is primarily mediated by IgE antibodies and mast cells, not T cells.
Which of the following is a major site of immune complex deposition in systemic lupus erythematosus (SLE)?
- A. Thyroid
- B. Glomerular basement membrane
- C. Peripheral nerves
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: Glomerular basement membrane. In SLE, immune complexes deposit in various tissues, leading to inflammation and damage. The glomerular basement membrane is a common site for immune complex deposition in SLE, resulting in lupus nephritis. The other choices are incorrect because immune complex deposition does not typically occur in the thyroid, peripheral nerves, or mast cells in SLE. Thyroid involvement in SLE is more related to autoimmune thyroiditis, while peripheral nerves are not a major site for immune complex deposition in this condition. Mast cells are primarily involved in allergic reactions and are not a major target in SLE.