Nokea
What was Edward Jenner's major contribution to immunology?
- A. Discovering antibodies
- B. Proposing innate immunity theory
- C. Developing the smallpox vaccine
- D. Discovering the germ theory of disease
Correct Answer: C
Rationale: Edward Jenner's major contribution to immunology was developing the smallpox vaccine. He introduced the concept of vaccination by using cowpox to protect against smallpox. This marked the beginning of modern immunization. Discovering antibodies (A) and proposing innate immunity theory (B) were not directly attributed to Jenner. Discovering the germ theory of disease (D) was later proposed by Louis Pasteur and Robert Koch, not Jenner. Overall, choice C is correct as it aligns with Jenner's groundbreaking work in immunization.
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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 opportunistic disease associated with AIDS is characterized by hyperpigmented lesions of skin, lungs, and gastrointestinal (GI) tract?
- A. Kaposi sarcoma
- B. Candida albicans
- C. Herpes simplex type 1 infection
- D. Varicella-zoster virus infection
Correct Answer: A
Rationale: Kaposi sarcoma is a tumor associated with AIDS and manifests as hyperpigmented lesions on the skin, lungs, and GI tract.
Which of the following DNA polymerases cleaves a DNA sequence at the direction of 5' → 3'?
- A. DNA polymerase I
- B. DNA polymerase II
- C. DNA polymerase III
- D. DNA polymerase IV
Correct Answer: A
Rationale: The correct answer is A: DNA polymerase I. DNA polymerase I has both 5' to 3' polymerase activity and 5' to 3' exonuclease activity, allowing it to cleave DNA in the 5' to 3' direction. This enzyme can remove RNA primers during DNA replication by cleaving them in the 5' to 3' direction and replace them with DNA nucleotides. DNA polymerase II, III, and IV do not have the same exonuclease activity as DNA polymerase I, so they are not capable of cleaving DNA sequences in the 5' to 3' direction like DNA polymerase I.
What is the primary cause of anaphylaxis?
- A. Immune complex deposition
- B. Systemic release of vasoactive mediators
- C. Localized mast cell degranulation
- D. T cell activation
Correct Answer: B
Rationale: The correct answer is B: Systemic release of vasoactive mediators. Anaphylaxis is a severe allergic reaction that is primarily caused by the systemic release of vasoactive mediators such as histamine, prostaglandins, and leukotrienes from mast cells and basophils. These mediators lead to widespread vasodilation, increased vascular permeability, bronchoconstriction, and systemic hypotension, resulting in the characteristic symptoms of anaphylaxis.
Choice A (Immune complex deposition) is incorrect because anaphylaxis is not caused by the deposition of immune complexes but rather by the immediate hypersensitivity reaction.
Choice C (Localized mast cell degranulation) is incorrect because anaphylaxis involves systemic mast cell degranulation leading to widespread effects throughout the body, not just localized reactions.
Choice D (T cell activation) is incorrect because anaphylaxis is primarily mediated by IgE antibodies and mast cells, not T cells.
What is characteristic of chronic inflammation?
- A. It may last 2 to 3 weeks.
- B. The injurious agent persists or repeatedly injures tissue.
- C. Infective endocarditis is an example of chronic inflammation.
- D. Neutrophils are the predominant cell type at the site of inflammation.
Correct Answer: B
Rationale: Chronic inflammation occurs when the cause of the initial injury persists or recurs, leading to ongoing tissue damage and repair. Unlike acute inflammation, it involves lymphocytes and macrophages rather than neutrophils.