Nokea
TLR-3 detects viruses found in:
- A. Cytosol
- B. Extracellular space
- C. Endosomes
- D. All of the above
Correct Answer: C
Rationale: TLR-3 detects viruses in endosomes. When a virus enters a host cell, it is often engulfed into endosomes. TLR-3 recognizes viral RNA within endosomes and triggers an immune response. Choices A and B are incorrect because TLR-3 does not detect viruses in the cytosol or extracellular space. Choice D is incorrect because TLR-3 specifically functions in endosomes to detect viral RNA.
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What is the role of complement component C3b in immune responses?
- A. Initiates MAC formation
- B. Acts as an opsonin to enhance phagocytosis
- C. Triggers inflammation
- D. Neutralizes cytokines
Correct Answer: B
Rationale: The correct answer is B: C3b acts as an opsonin to enhance phagocytosis. C3b binds to pathogens and enhances their recognition by phagocytic cells, facilitating their engulfment and destruction. This process is crucial for efficient immune responses. A, MAC formation, is initiated by the membrane attack complex, not C3b. C, inflammation, is triggered by various mediators such as histamine and cytokines, not C3b. D, neutralizing cytokines, is not a function of C3b; cytokines are regulatory proteins involved in immune responses.
Which type of cell produces antibodies?
- A. Helper T cells
- B. Plasma cells
- C. Cytotoxic T cells
- D. Regulatory T cells
Correct Answer: B
Rationale: The correct answer is B: Plasma cells. Plasma cells are a type of white blood cell that produces antibodies in response to antigens. They are essential in the immune response to help fight off infections and other diseases. Helper T cells (A) assist other immune cells but do not directly produce antibodies. Cytotoxic T cells (C) are responsible for killing infected cells, not producing antibodies. Regulatory T cells (D) help regulate the immune response but do not produce antibodies. In summary, only plasma cells are specifically designed to produce antibodies in the immune system.
The reason for naming the closed circulatory systems
- A. Carries blood in opens vessels
- B. Moves blood through the veins and arteries
- C. Blood stays confined to vessels
- D. Returns blood to the heart
Correct Answer: C
Rationale: The correct answer is C because a closed circulatory system means that blood stays confined to vessels, providing efficient transport and preventing blood loss. Option A is incorrect because a closed system does not have open vessels. Option B is incorrect because veins and arteries are part of both closed and open circulatory systems. Option D is incorrect because returning blood to the heart is a function of both closed and open circulatory systems.
Which condition is associated with granulomas?
- A. Crohn's disease
- B. Grave's disease
- C. Anaphylaxis
- D. Eczema
Correct Answer: A
Rationale: The correct answer is A: Crohn's disease. Granulomas are a characteristic feature of Crohn's disease, forming in response to chronic inflammation in the gastrointestinal tract. Granulomas consist of immune cells and are seen in the affected tissues of Crohn's patients.
Choice B: Grave's disease is an autoimmune condition affecting the thyroid gland, not typically associated with granulomas.
Choice C: Anaphylaxis is a severe allergic reaction involving the immune system's response, but it does not lead to granuloma formation.
Choice D: Eczema is a skin condition characterized by inflammation and itching, but it does not typically involve granulomas.
Sacl restriction endonuclease reactions produce fragments with
- A. blunt end
- B. None of the options are correct
- C. 5' cohesive ends
- D. 3' cohesive ends
Correct Answer: C
Rationale: The correct answer is C: 5' cohesive ends. Sacl restriction endonuclease cuts DNA at specific recognition sites, leaving single-stranded overhangs called cohesive ends. In this case, Sacl creates 5' overhangs, resulting in fragments with 5' cohesive ends. Blunt ends (option A) have no overhangs, making them incorrect. Options B and D are incorrect as they do not align with the specific characteristic of Sacl restriction endonuclease's cleavage pattern.