Nokea
What is a characteristic feature of Goodpasture's syndrome?
- A. Granuloma formation
- B. Pulmonary hemorrhage and glomerulonephritis
- C. Contact dermatitis
- D. Bronchoconstriction and vasodilation
Correct Answer: B
Rationale: The correct answer is B: Pulmonary hemorrhage and glomerulonephritis. Goodpasture's syndrome is an autoimmune disease characterized by the presence of anti-glomerular basement membrane antibodies, leading to damage in the kidneys (glomerulonephritis) and lungs (pulmonary hemorrhage). Granuloma formation (A), contact dermatitis (C), and bronchoconstriction and vasodilation (D) are not characteristic features of Goodpasture's syndrome. Granulomas are more commonly seen in conditions like sarcoidosis, contact dermatitis is an inflammatory skin condition, and bronchoconstriction and vasodilation are features of allergic reactions or asthma, not typically seen in Goodpasture's syndrome.
You may also like to solve these questions
Which pathway of the complement system involves properdin, Factor B, and Factor D?
- A. Classical pathway
- B. Alternative pathway
- C. Lectin pathway
- D. Terminal pathway
Correct Answer: B
Rationale: The correct answer is B: Alternative pathway. This pathway involves properdin, Factor B, and Factor D. Properdin stabilizes the C3 convertase complex formed by Factor B and Factor D, leading to the amplification of the complement cascade. The other choices are incorrect because:
A: Classical pathway is initiated by antigen-antibody complexes binding to C1q.
C: Lectin pathway is activated by lectins binding to carbohydrates on pathogen surfaces.
D: Terminal pathway involves the formation of the membrane attack complex.
What is the outcome of clonal selection after a lymphocyte is activated?
- A. Cytokine suppression
- B. Formation of memory and effector cells
- C. Antigen elimination without cellular proliferation
- D. Destruction of the lymphocyte
Correct Answer: B
Rationale: The correct answer is B because clonal selection during lymphocyte activation leads to the formation of memory and effector cells. This process involves the proliferation and differentiation of the activated lymphocyte into these specialized cells, which play crucial roles in immune responses upon encountering the same antigen in the future. Cytokine suppression (choice A) is not the direct outcome of clonal selection but may be a regulatory mechanism during immune responses. Antigen elimination without cellular proliferation (choice C) is not accurate as clonal selection involves the expansion of specific lymphocyte clones. Destruction of the lymphocyte (choice D) is not the outcome of clonal selection, as activated lymphocytes undergo proliferation and differentiation rather than destruction.
Following class of restriction endonucleases is commercially available and used in recombinant DNA technology:
- A. Class 1
- B. Class 2
- C. Class 3
- D. Class 5
Correct Answer: B
Rationale: The correct answer is B: Class 2. Class 2 restriction endonucleases are commonly used in recombinant DNA technology due to their specificity for recognizing short DNA sequences and cleaving within or near these sequences. They are commercially available, easy to use, and have well-defined recognition sites, making them ideal for molecular cloning applications.
Choice A (Class 1) is incorrect because Class 1 enzymes require both ATP and S-adenosyl methionine for activity, making them less practical for routine laboratory use.
Choice C (Class 3) is incorrect because Class 3 enzymes cleave DNA at two sites, potentially leading to unwanted DNA fragmentation in recombinant DNA technology.
Choice D (Class 5) is incorrect because Class 5 restriction enzymes do not exist in the classification system of restriction endonucleases.
The differentiation of activated Th cells into various effector subsets depends mostly on:
- A. Signal 1 of activation
- B. The influence of polarizing cytokines secreted by dendritic cells
- C. Whether the T cell expresses CD4 or CD8
- D. The duration of signaling induced by TCR binding to peptide-MHC
Correct Answer: B
Rationale: The correct answer is B because polarizing cytokines secreted by dendritic cells play a crucial role in determining the differentiation of activated Th cells into specific effector subsets. These cytokines guide the Th cells towards different functional phenotypes, such as Th1, Th2, Th17, or Treg cells. This process helps tailor the immune response to the specific type of pathogen encountered. Choices A, C, and D are incorrect because while signal 1 of activation, T cell receptor co-receptors, and duration of signaling are important factors in T cell activation and differentiation, they do not have as direct and significant an impact on effector subset differentiation as the influence of polarizing cytokines.
Which of the following is considered a defining characteristic of a TH2 response?
- A. Production of IgM antibodies
- B. Activation of CTL
- C. Recruitment and activation of neutrophils
- D. Production of IgE antibodies
Correct Answer: D
Rationale: The correct answer is D: Production of IgE antibodies. A TH2 response is characterized by the production of IgE antibodies, which are essential in allergic reactions. IgM antibodies (A) are produced during the primary immune response. Activation of CTL (B) is associated with a TH1 response. Neutrophils (C) are primarily involved in the innate immune response and are not specific to TH2 responses. In summary, the production of IgE antibodies is a defining characteristic of a TH2 response, distinguishing it from other immune responses.