Nokea
The discovery of immunoglobulin gene rearrangement helped to explain:
- A. How the number of different immunoglobulins produced by an individual can be far greater than the number of genes in the human genome
- B. How the number of genes in the human genome can be far greater than the number of different immunoglobulins produced by an individual
- C. How thousands of immunoglobulin chains of different sequence may be produced by a single B cell
- D. Both A and C are correct
Correct Answer: A
Rationale: The correct answer is A: How the number of different immunoglobulins produced by an individual can be far greater than the number of genes in the human genome. Immunoglobulin gene rearrangement occurs during B cell development, leading to the generation of a diverse repertoire of antibodies from a limited number of genes. This process allows for the production of a vast array of immunoglobulins through mechanisms like V(D)J recombination. Choice B is incorrect because the gene rearrangement process actually enables a single gene to encode for multiple immunoglobulins. Choice C is partially correct but does not fully capture the significance of gene rearrangement in expanding the diversity of immunoglobulins beyond what the genome would suggest. Choice D is incorrect as it combines a correct statement (A) with an incomplete statement (C).
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Which of the following causes memory cells to convert to plasma cells?
- A. An organ transplant
- B. Release of lymphokines
- C. Re-exposure to a specific antigen
- D. Initial exposure to an antigen
Correct Answer: C
Rationale: Memory cells convert to plasma cells upon re-exposure to a specific antigen which triggers a rapid and robust immune response.
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 rationale describes treatment of atopic allergies with immunotherapy?
- A. It decreases the levels of allergen-specific T helper cells.
- B. It decreases the level of IgE so that it does not react as readily with an allergen.
- C. It stimulates increased IgG to bind with allergen-reactive sites, preventing mast cell-bound IgE reactions.
- D. It gradually increases the amount of allergen in the body until it is no longer recognized as foreign and does not elicit an antibody reaction.
Correct Answer: C
Rationale: Immunotherapy stimulates the production of blocking IgG antibodies, which compete with IgE for allergen-binding sites, preventing mast cell activation.
Which of the following statement concerning Influenza infection is NOT true?
- A. There is evidence that the infection is less common in spring/summer because the transmission of bigger droplets formed at higher temperatures requires more close contact among people
- B. People infected with Flu can spread the disease before becoming symptomatic
- C. The human strains infect cells of the respiratory tract and also extensively infect epithelial cells throughout the body, explaining the systemic symptoms of influenza
- D. The virus hemagglutinin (HA) allows cell infection via the binding to sialic acid on carbohydrates expressed on host cells
Correct Answer: C
Rationale: The correct answer is C because it states that human strains of Influenza extensively infect epithelial cells throughout the body, which is not true. Influenza primarily infects cells of the respiratory tract, leading to respiratory symptoms. Systemic symptoms such as fever, fatigue, and muscle aches are more related to the body's immune response rather than widespread infection of epithelial cells throughout the body. This statement is incorrect as it misrepresents the pathogenesis of Influenza. Choices A, B, and D are incorrect because they are all true statements supported by scientific evidence regarding Influenza transmission, asymptomatic spread, and viral entry mechanism, respectively.
A patient with chronic hepatitis C has been receiving interferon alfa-2a (Roferon-A) injections for the last month. Which information gathered during a visit in the home to conduct an interview and physical assessment is most important to communicate to the physician?
- A. The patient has chronic nausea and vomiting.
- B. The patient is giving the medication by the IM route to her lateral thigh.
- C. The patient has a temperature of 99.7°F orally.
- D. The patient complains of chronic fatigue,muscle aches and anorexia.
Correct Answer: A
Rationale: Chronic nausea and vomiting can lead to dehydration and malnutrition which are serious complications that need to be addressed. While the other symptoms are common side effects of interferon therapy they are less urgent than persistent nausea and vomiting.