Nokea
What is the primary function of lymph nodes?
- A. Producing red blood cells
- B. Filtering lymph and facilitating immune responses
- C. Synthesizing antibodies
- D. Generating cytokines
Correct Answer: B
Rationale: The primary function of lymph nodes is to filter lymph and facilitate immune responses. Lymph nodes contain immune cells that help recognize and fight off infections. They filter lymph by trapping and removing pathogens and foreign particles. This process helps in activating the immune response to protect the body. Choices A, C, and D are incorrect because lymph nodes do not produce red blood cells, synthesize antibodies, or generate cytokines. These functions are carried out by other organs and cells in the body.
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In reference to the flow diagram below respond to the following question. The annotation A refers to which sites
- A. Annealing
- B. Melting
- C. Restriction
- D. RNAse
Correct Answer: C
Rationale: The correct answer is C: Restriction. In a flow diagram, the annotation "Restriction" likely indicates the site where a DNA molecule is being cut by a restriction enzyme. This process is essential in molecular biology for DNA manipulation.
Choice A: Annealing involves the process of complementary DNA strands coming together, usually during PCR or hybridization.
Choice B: Melting refers to the separation of double-stranded DNA into single strands, often seen in denaturation steps.
Choice D: RNAse is an enzyme that specifically degrades RNA molecules, not involved in the DNA manipulation processes indicated in the diagram.
What disease is associated with autoantibodies binding to type IV collagen?
- A. Sarcoidosis
- B. Goodpasture's syndrome
- C. Systemic lupus erythematosus (SLE)
- D. Rheumatoid arthritis
Correct Answer: B
Rationale: The correct answer is B: Goodpasture's syndrome. This disease is specifically associated with autoantibodies targeting type IV collagen in the basement membranes of the kidneys and lungs, leading to glomerulonephritis and pulmonary hemorrhage. Sarcoidosis (A) involves non-caseating granulomas, not collagen autoantibodies. Systemic lupus erythematosus (SLE) (C) is associated with various autoantibodies but not specifically targeting type IV collagen. Rheumatoid arthritis (D) is characterized by autoantibodies against citrullinated peptides and synovial tissue, not type IV collagen.
Which of the following processes does not require the involvement of an antigen-specific T helper cell?
- A. Somatic hypermutation
- B. VDJ gene rearrangement
- C. Immunoglobulin class switching
- D. Memory cell differentiation
Correct Answer: B
Rationale: Correct Answer: B (VDJ gene rearrangement)
Rationale:
1. VDJ gene rearrangement occurs during B cell development in the bone marrow, independent of T helper cells.
2. Somatic hypermutation and immunoglobulin class switching require T helper cell interactions.
3. Memory cell differentiation also involves T helper cells for activation and differentiation.
4. Therefore, VDJ gene rearrangement is the only process not directly dependent on antigen-specific T helper cells.
Which patient is at risk for hypernatremia?
- A. Has a deficiency of aldosterone
- B. Has prolonged vomiting and diarrhea
- C. Receives excessive IV 5% dextrose solution
- D. Has impaired consciousness and decreased thirst sensitivity
Correct Answer: D
Rationale: Impaired consciousness leads to decreased thirst sensitivity, preventing adequate water intake and increasing sodium concentration in the blood.
PNAd is expressed on
- A. HEV
- B. Lymphocytes
- C. Dendritic cells
- D. Thymus
Correct Answer: A
Rationale: The correct answer is A: HEV (High Endothelial Venules). PNAd is a ligand expressed on high endothelial venules, which helps in the recruitment of lymphocytes from the bloodstream into secondary lymphoid organs. PNAd is not primarily expressed on lymphocytes themselves (B) or dendritic cells (C). While PNAd can be involved in thymocyte migration to the thymus, it is not expressed on the thymus itself (D). Thus, the correct answer is A as it directly relates to the function and location of PNAd expression.