Nokea
Which of the following is NOT true concerned with Leishmania
- A. It is a unicellular parasite
- B. Proliferates inside phagocytic cells
- C. Transmitted by sand flies
- D. Protection is mainly mediated by IgE
Correct Answer: D
Rationale: The correct answer is D because protection against Leishmania is mainly mediated by cell-mediated immune responses, not IgE antibodies. IgE is not typically involved in protection against intracellular parasites like Leishmania. A: Leishmania is indeed a unicellular parasite. B: Leishmania proliferates inside phagocytic cells, particularly macrophages. C: Leishmania is transmitted by sand flies during blood meals.
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Autoimmune diseases are associated with several susceptibility factors. Environmental factors associated with increased risk of autoimmune disease include:
- A. Infections
- B. Level of exposure to the sun
- C. Imbalance of microbiota composition
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Autoimmune diseases have complex causes, involving genetic predisposition and environmental factors. Infections can trigger autoimmune responses, sunlight exposure can influence immune function, and an imbalance in microbiota composition can lead to dysregulated immune responses. Therefore, all three factors can contribute to an increased risk of autoimmune diseases. Choices A, B, and C individually are all associated with autoimmune diseases, making option D the correct choice.
In the late 1890s, 'cellularists' and 'humoralists' were intensively arguing about the key components driving the immune response. What was a crucial finding that led the humoralists to dominate the field in the following 50 years?
- A. The demonstration of the Germ Theory of disease
- B. The discovery that cell-free serum could transfer immunity from an immunized animal to a non-immunized one
- C. The discovery of the tuberculin reaction
- D. The determination of the antibody structure
Correct Answer: B
Rationale: The correct answer is B, the discovery that cell-free serum could transfer immunity. This finding led humoralists to dominate because it supported the idea of circulating antibodies in the serum being responsible for immunity. This concept aligned with the humoralist theory, which focused on the role of antibodies in immune response. The ability of cell-free serum to transfer immunity provided direct evidence for humoralists' beliefs.
Choice A (The demonstration of the Germ Theory of disease) is incorrect because while it was a significant advancement in understanding disease, it did not directly impact the argument between cellularists and humoralists regarding the immune response.
Choice C (The discovery of the tuberculin reaction) is incorrect as it was more relevant to the understanding of the immune response to tuberculosis specifically, rather than the broader debate between cellularists and humoralists.
Choice D (The determination of the antibody structure) is incorrect because while understanding antibody structure is crucial, it did not have as direct an impact on the dominance of
What is a key difference between innate and adaptive immunity?
- A. Innate immunity develops memory
- B. Adaptive immunity is always functional
- C. Innate immunity is rapid and non-specific
- D. Adaptive immunity does not require activation
Correct Answer: C
Rationale: Correct Answer: C
Rationale:
1. Innate immunity is rapid: It provides immediate defense against pathogens.
2. Innate immunity is non-specific: It reacts in the same way to all pathogens.
3. Adaptive immunity, on the other hand, is slower and pathogen-specific.
4. Adaptive immunity develops memory to provide long-lasting protection.
Summary:
A: Innate immunity does not develop memory; adaptive immunity does.
B: Adaptive immunity may not always be functional due to various factors.
D: Adaptive immunity requires activation through exposure to specific antigens.
Which one of the following processes emerged earliest during the course of evolution?
- A. Antigen presentation
- B. Antibody production
- C. Phagocytosis
- D. Thymic education
Correct Answer: C
Rationale: The correct answer is C: Phagocytosis. Phagocytosis is a fundamental process that emerged early in evolution for cellular organisms to engulf and digest particles. This process is essential for basic survival and defense mechanisms.
A: Antigen presentation and B: Antibody production are more advanced immune responses that occur in higher organisms and require a complex immune system.
D: Thymic education is a process specific to vertebrates involving the maturation and selection of T cells, which is a more evolved mechanism compared to phagocytosis.
Therefore, phagocytosis is the earliest process among the options listed as it is essential for basic cellular survival and predates the development of advanced immune responses.
L-Selectin is
- A. Expressed on effector T cells
- B. Expressed on HEV
- C. Expressed on naïve T cells
- D. Required to extravasate into tissues
Correct Answer: C
Rationale: The correct answer is C: Expressed on naïve T cells. L-Selectin is a cell adhesion molecule expressed on the surface of naïve T cells. It plays a crucial role in the initial attachment of T cells to high endothelial venules (HEV) in lymphoid tissues, facilitating T cell entry into lymph nodes. It specifically binds to ligands on HEV, allowing T cells to extravasate into lymphoid tissues. Choice A is incorrect because L-Selectin is primarily expressed on naïve T cells rather than effector T cells. Choice B is incorrect as L-Selectin is expressed on HEV, not by them. Choice D is incorrect because L-Selectin is involved in the initial attachment of T cells to endothelial cells, rather than being required for extravasation into tissues.