Nokea
Cells involved in allergic reactions include
- A. Mast cells
- B. Eosinophils
- C. Basophils
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Mast cells, eosinophils, and basophils are all involved in allergic reactions. Mast cells release histamine, leading to inflammation. Eosinophils are involved in allergic responses and parasitic infections. Basophils release histamine and other inflammatory mediators. Therefore, all three cell types play a crucial role in allergic reactions. Choices A, B, and C alone are incorrect because each cell type individually participates in allergic reactions.
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What are characteristics of the phosphate buffer system (select all that apply)?
- A. Neutralizes a strong base to a weak base and water
- B. Resultant sodium biphosphate is eliminated by kidneys
- C. Free acid radicals dissociate into H+ and CO2,buffering excess base
- D. Neutralizes a strong acid to yield sodium biphosphate,a weak acid and salt
Correct Answer: B
Rationale: Phosphate buffers neutralize strong bases/acid, form sodium biphosphate, and eliminate it through the kidneys.
Terminal deoxynucleotidyl transferase catalyzed reactions produce fragments with
- A. poly A or poly C tails
- B. poly C tails
- C. poly A tails
- D. poly A or poly T tail
Correct Answer: A
Rationale: Terminal deoxynucleotidyl transferase (TdT) adds nucleotides to the 3' end of DNA fragments in a template-independent manner. This results in the production of fragments with poly A or poly C tails. TdT does not add poly T tails, making option D incorrect. It also does not specifically add only poly C tails (option B) or poly A tails (option C). The addition of poly A or poly C tails by TdT is essential for techniques like DNA sequencing and PCR, where these tails are utilized for downstream applications.
Which of the following statements is NOT true
- A. Light chains isotypes are functionally different
- B. The antigen binding site of a B cell receptor is identical to the antigen binding site of antibodies secreted by the same B cell
- C. Both heavy and light chain domains assume a compact barrel structure
- D. The hinge region assumes a more open and flexible structure
Correct Answer: A
Rationale: The correct answer is A: Light chains isotypes are functionally different. This statement is NOT true because light chain isotypes (kappa and lambda) have distinct primary structures but serve the same function in antigen binding. The heavy chain determines the effector function of antibodies. The other choices are correct: B) The antigen binding site of a B cell receptor is identical to the antigen binding site of antibodies secreted by the same B cell, as both use the same variable regions for antigen recognition. C) Both heavy and light chain domains assume a compact barrel structure, which is essential for antibody stability and function. D) The hinge region assumes a more open and flexible structure, allowing antibodies to bind antigens at different orientations.
Select incorrect mechanism for the development of autoimmune disorder.
- A. A second exposure to an allergen.
- B. Cross-reaction of antibodies formed against foreign antigens with self-antigens.
- C. Exposure of previously 'hidden' self-antigens to the adaptive immune system.
- D. Mutation followed by the appearance of membrane proteins not previously present.
Correct Answer: A
Rationale: The correct answer is A. A second exposure to an allergen does not lead to the development of autoimmune disorders. The key mechanisms involved in autoimmune disorders are self-tolerance breakdown and immune system attacking self-antigens.
Explanation:
1. B: Cross-reaction of antibodies formed against foreign antigens with self-antigens is a possible mechanism for autoimmune disorders.
2. C: Exposure of previously 'hidden' self-antigens to the adaptive immune system can trigger autoimmune responses.
3. D: Mutation followed by the appearance of membrane proteins not previously present can lead to autoimmune disorders, as the immune system may recognize these proteins as foreign.
Summary:
Choice A is incorrect because a second exposure to an allergen does not cause the immune system to target self-antigens, which is the hallmark of autoimmune disorders. Choices B, C, and D are more plausible mechanisms for the development of autoimmune disorders.
The National Marrow Donor Program obtains hematopoietic stem cells from donors for recipients in need. When discussing this donation with the donor, what should the nurse know about these stem cells?
- A. They must come from an embryo or umbilical cord.
- B. These cells will form new blood cells for the recipient.
- C. Taking these cells will cause the donor to become anemic.
- D. These cells must be removed with a bone marrow aspiration.
Correct Answer: B
Rationale: Hematopoietic stem cells donated through programs like the National Marrow Donor Program help generate new blood cells for recipients, aiding in treating various blood disorders.