Nokea
An example of a preformed chemical barrier is:
- A. Mucus
- B. Lysozyme
- C. Tight junctions in epithelial cells
- D. Cilia in the respiratory tract
Correct Answer: B
Rationale: Step-by-step rationale:
1. Lysozyme is an enzyme that destroys bacterial cell walls.
2. This action acts as a preformed chemical barrier against pathogens.
3. Mucus (choice A) is a physical barrier, not a preformed chemical one.
4. Tight junctions (choice C) and cilia (choice D) are structural components, not chemical barriers.
Summary:
- Choice B, Lysozyme, is correct as it actively targets and destroys pathogens.
- Choices A, C, and D are incorrect as they do not directly function as preformed chemical barriers.
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Which type of cancer is most commonly associated with exposure to asbestos?
- A. Lung cancer
- B. Leukemia
- C. Breast cancer
- D. Prostate cancer
Correct Answer: A
Rationale: Asbestos exposure is strongly linked to lung cancer, particularly mesothelioma.
Dendritic cells play a role in:
- A. Costimulation of naïve T cells
- B. Processing of protein antigens to generate peptides
- C. Presentation of peptide-MHC complexes for recognition by T cell receptors
- D. All of the above
Correct Answer: D
Rationale: Dendritic cells play a crucial role in the immune system. Firstly, they provide costimulation to activate naïve T cells (A). Secondly, they process protein antigens into peptides for antigen presentation (B). Finally, dendritic cells present peptide-MHC complexes to T cell receptors for immune response activation (C). Therefore, the correct answer is D, as dendritic cells are involved in all these processes essential for initiating and regulating immune responses. Choices A, B, and C are incorrect as they are individual roles of dendritic cells and do not encompass the full range of functions that dendritic cells perform.
Which of the following is a major site of immune complex deposition in systemic lupus erythematosus (SLE)?
- A. Thyroid
- B. Glomerular basement membrane
- C. Peripheral nerves
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: Glomerular basement membrane. In SLE, immune complexes deposit in various tissues, leading to inflammation and damage. The glomerular basement membrane is a common site for immune complex deposition in SLE, resulting in lupus nephritis. The other choices are incorrect because immune complex deposition does not typically occur in the thyroid, peripheral nerves, or mast cells in SLE. Thyroid involvement in SLE is more related to autoimmune thyroiditis, while peripheral nerves are not a major site for immune complex deposition in this condition. Mast cells are primarily involved in allergic reactions and are not a major target in SLE.
Which of the following statements concerning Influenza Hemagglutinin (HA) and Neuraminidase (N) is incorrect
- A. Both mutate frequently due to antigenic drift
- B. Function of N is to release new viral particles from infected cells
- C. HA binds to terminal sialic acid on cell surface molecules found on lung epithelial cells
- D. Tamiflu interferes with the attachment of HA to sialic acid
Correct Answer: D
Rationale: The correct answer is D. Tamiflu interferes with the function of Neuraminidase (N), not Hemagglutinin (HA). HA binds to sialic acid on cell surface molecules, not N. N's function is to release new viral particles. Both HA and N undergo antigenic drift. Therefore, choice D is incorrect as it misrepresents the mechanism of action of Tamiflu.
Which of the following is NOT an example of a pathogen-associated molecular pattern (PAMP)?
- A. Lipopolysaccharide (LPS)
- B. Peptidoglycan
- C. Viral RNA
- D. MHC molecules
Correct Answer: D
Rationale: The correct answer is D, MHC molecules. PAMPs are conserved molecules found on pathogens that can trigger an immune response. MHC molecules are not PAMPs; they are part of the host's immune system used to present antigens to T cells. LPS, peptidoglycan, and viral RNA are examples of PAMPs as they are specific molecules found on pathogens that can be recognized by pattern recognition receptors on immune cells to initiate an immune response.