Nokea
Cancer cells go through stages of development. What accurately describes the stage of promotion (select all that apply)?
- A. Obesity is an example of a promoting factor
- B. The stage is characterized by increased growth rate and metastasis
- C. Withdrawal of promoting factors will reduce the risk of cancer development
- D. Tobacco smoke is a complete carcinogen that is capable of both initiation and promotion
Correct Answer: C
Rationale: Promotion involves enhancing the growth of initiated cells. Obesity and tobacco smoke are examples of promoting factors, and withdrawal of such factors can reduce cancer risk.
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All of the following are true about antibodies, EXCEPT which one?
- A. They fix complement.
- B. They occur on the surface of B-lymphocyte
- C. They predominate the primary immune response to antigen.
- D. have a single, defined amino acid sequence due to variability.
Correct Answer: D
Rationale: The correct answer is D because antibodies do not have a single, defined amino acid sequence due to variability in their structure. This variability is a result of somatic recombination and hypermutation.
A: Antibodies can fix complement, leading to the destruction of pathogens.
B: Antibodies are produced by B-lymphocytes and can occur on their surface as B-cell receptors.
C: Antibodies predominate the secondary immune response, not the primary response, as memory B-cells are generated during the primary response for a quicker and more robust secondary response.
What is the mechanism of tissue damage in Type II hypersensitivity?
- A. Immune complex deposition
- B. Antibody binding to cell surface antigens, triggering complement activation or phagocytosis
- C. Mast cell degranulation
- D. T cell-mediated cytotoxicity
Correct Answer: B
Rationale: The correct answer is B: Antibody binding to cell surface antigens, triggering complement activation or phagocytosis. In Type II hypersensitivity, antibodies bind to antigens on host cells, leading to complement activation or phagocytosis by immune cells. This results in cell damage or destruction. Immune complex deposition (A) is more characteristic of Type III hypersensitivity. Mast cell degranulation (C) is seen in Type I hypersensitivity. T cell-mediated cytotoxicity (D) is associated with Type IV hypersensitivity, not Type II. Therefore, choice B is the most accurate mechanism of tissue damage in Type II hypersensitivity.
Select the correct number of statements that are true.
- A. Only 1 and 3 are correct.
- B. Only 2 and 4 are correct.
- C. Only 3 and 4 are correct.
- D. All of the above are correct.
Correct Answer: A
Rationale: The correct answer is A. Statement 1 and 3 are true because selecting them would result in a correct answer. Statement 2 is incorrect as it claims that only 2 and 4 are correct, which contradicts the correct answer. Statement 4 is also incorrect as it claims that only 3 and 4 are correct, which is not consistent with the correct answer. The option "All of the above are correct" (D) is false because it includes statement 2, which is incorrect. Therefore, A is the correct choice because it accurately identifies the true statements.
Which scientist proposed the concept of clonal selection?
- A. Paul Ehrlich
- B. Macfarlane Burnet
- C. Louis Pasteur
- D. Elie Metchnikoff
Correct Answer: B
Rationale: The correct answer is B: Macfarlane Burnet. Burnet proposed the concept of clonal selection in the 1950s to explain how the immune system recognizes and responds to specific antigens. He suggested that lymphocytes with receptors specific to antigens undergo clonal expansion upon encountering the antigen. This hypothesis laid the groundwork for our understanding of adaptive immunity.
A: Paul Ehrlich developed the side-chain theory of antibody formation, not clonal selection.
C: Louis Pasteur is known for his work in microbiology and vaccination, not clonal selection.
D: Elie Metchnikoff is credited with discovering phagocytosis, not clonal selection.
The nurse uses many precautions during IV administration of vesicant chemotherapeutic agents, primarily to prevent
- A. septicemia
- B. extravasation
- C. catheter occlusion
- D. anaphylactic shock
Correct Answer: B
Rationale: Extravasation of vesicant agents can cause severe tissue damage, so precautions are essential.