Nokea
What is the primary advantage of Toll-like receptors (TLRs)?
- A. They are highly specific to individual pathogens
- B. They recognize common molecular patterns shared by groups of microbes
- C. They activate B cell antibody production
- D. They require antigen presentation to function
Correct Answer: B
Rationale: The correct answer is B because Toll-like receptors (TLRs) recognize common molecular patterns shared by groups of microbes, allowing for rapid detection of a wide range of pathogens. This recognition triggers immune responses without the need for prior exposure to the specific pathogen. The other choices are incorrect because:
A: TLRs are not highly specific to individual pathogens but rather recognize common patterns.
C: TLRs do not directly activate B cell antibody production; they initiate immune responses by activating various immune cells.
D: TLRs do not require antigen presentation to function; they directly recognize microbial patterns.
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What condition is associated with C1q deficiency?
- A. Cancer
- B. Systemic lupus erythematosus (SLE)
- C. HIV/AIDS
- D. Chronic obstructive pulmonary disease
Correct Answer: B
Rationale: Rationale: C1q is a component of the classical complement pathway, crucial for immune complex clearance. Its deficiency is associated with SLE due to impaired immune complex removal, leading to autoantibody deposition and inflammation. Cancer, HIV/AIDS, and COPD are not directly linked to C1q deficiency.
Which antibody isotype is primarily involved in mucosal immunity?
- A. IgG
- B. IgA
- C. IgM
- D. IgE
Correct Answer: B
Rationale: The correct answer is B: IgA. IgA is primarily involved in mucosal immunity as it is the most abundant antibody present in mucosal secretions like saliva, tears, and breast milk. IgA plays a crucial role in preventing pathogens from entering the body through mucosal surfaces. IgG is more involved in systemic immunity, IgM is the first antibody produced in response to an infection, and IgE is associated with allergic reactions. Therefore, IgA is the most appropriate choice for mucosal immunity.
How does interferon help the body’s natural defenses?
- A. Directly attacks and destroys virus-infected cells
- B. Augments the immune response by activating phagocytes
- C. Induces production of antiviral proteins in cells that prevent viral replication
- D. Is produced by viral infected cells and prevents the transmission of the virus to adjacent cells
Correct Answer: C
Rationale: Interferons induce the production of antiviral proteins in uninfected cells, preventing viral replication and spread.
What are haematopoietic stem cells responsible for?
- A. Differentiating into lymph nodes
- B. Producing immune cells
- C. Generating cytokines
- D. Suppressing pathogens directly
Correct Answer: B
Rationale: Haematopoietic stem cells are responsible for producing immune cells. These stem cells differentiate into various types of blood cells, including white blood cells that play a crucial role in the immune system. They do not differentiate into lymph nodes (A), generate cytokines (C), or suppress pathogens directly (D). The correct answer (B) aligns with the primary function of haematopoietic stem cells in the production of immune cells.
Memory T cells
- A. Recirculate through blood and secondary lymphoid tissues
- B. Have never encountered antigen
- C. Have a lower threshold of activation than naïve T cells
- D. Have a higher frequency than their naïve counterparts
Correct Answer: C
Rationale: The correct answer is C because memory T cells have a lower threshold of activation than naïve T cells. This is because memory T cells have already been primed by previous exposure to antigens, making them more responsive upon re-exposure. This heightened sensitivity allows memory T cells to mount a faster and stronger immune response upon encountering the same antigen again.
Choice A is incorrect because memory T cells primarily reside in peripheral tissues and not in secondary lymphoid tissues. Choice B is incorrect because memory T cells have encountered antigens before. Choice D is incorrect because memory T cells exist in a lower frequency compared to naïve T cells due to clonal expansion during the primary immune response.