Nokea
The hypervariable regions
- A. Are also called Complementary Determining Regions
- B. Are localized in the constant region of an antibody molecule
- C. Are not found in the secreted form of antibodies
- D. Are found only in heavy chains
Correct Answer: A
Rationale: Step 1: Hypervariable regions are responsible for antigen binding specificity.
Step 2: Complementary Determining Regions (CDRs) are the specific locations within the hypervariable regions.
Step 3: As CDRs are part of the hypervariable regions, choice A is correct.
Summary: Choices B, C, and D are incorrect because hypervariable regions are not in the constant region, are present in secreted antibodies, and are found in both heavy and light chains.
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A patient who has a large amount of carbon dioxide in the blood also has what in the blood?
- A. Large amount of carbonic acid and low hydrogen ion concentration
- B. Small amount of carbonic acid and low hydrogen ion concentration
- C. Large amount of carbonic acid and high hydrogen ion concentration
- D. Small amount of carbonic acid and high hydrogen ion concentration
Correct Answer: C
Rationale: Excess CO2 forms carbonic acid, increasing hydrogen ion concentration and lowering pH.
Molecules that are considered members of the 'immunoglobulin superfamily':
- A. Contain one or more protein domains with a compact barrel structure
- B. Are always lymphocyte antigen receptors
- C. Are highly unstable relative to other proteins
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A because molecules in the immunoglobulin superfamily typically contain one or more protein domains with a compact barrel structure. This structure is characteristic of immunoglobulin-like domains found in proteins involved in immune responses. Choice B is incorrect because not all members of the immunoglobulin superfamily are lymphocyte antigen receptors. Choice C is incorrect as these molecules are not necessarily highly unstable compared to other proteins. Therefore, the correct answer is A as it accurately describes a common structural feature of molecules in the immunoglobulin superfamily.
A cell type capable of killing virus-infected cells that provides early protection against viral infection is
- A. Eosinophils
- B. NK cells
- C. Neutrophils
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: NK cells. NK cells are part of the innate immune system and can directly kill virus-infected cells, providing early protection against viral infections. They do not require prior exposure to the virus to initiate their killing mechanism, making them crucial for early defense. Eosinophils (A), Neutrophils (C), and Mast cells (D) are not primarily involved in killing virus-infected cells. Eosinophils are more associated with parasitic infections, Neutrophils are primarily involved in bacterial infections, and Mast cells are involved in allergic reactions.
Defensins are
- A. Released by mast cells during an allergic reaction
- B. Membrane-disrupting peptides
- C. Acute phase proteins
- D. Opsonins
Correct Answer: B
Rationale: The correct answer is B: Membrane-disrupting peptides. Defensins are antimicrobial peptides that disrupt bacterial cell membranes. This disrupts the integrity of the bacterial cell, leading to cell lysis and death. Choice A is incorrect because mast cells release histamines, not defensins. Choice C is incorrect as acute phase proteins are involved in the immune response to inflammation. Choice D is incorrect as opsonins are molecules that enhance phagocytosis of pathogens by immune cells.
Which complement components are primarily involved in Type III hypersensitivity?
- A. C1 and C4
- B. C3a and C5a
- C. C5b and C6
- D. C2 and C7
Correct Answer: B
Rationale: The correct answer is B: C3a and C5a. In Type III hypersensitivity reactions, immune complexes form and deposit in tissues, leading to complement activation. C3a and C5a are anaphylatoxins released during complement activation, causing inflammation and tissue damage in Type III hypersensitivity.
Rationale:
A: C1 and C4 are primarily involved in Type I hypersensitivity reactions.
C: C5b and C6 are part of the membrane attack complex in the classical pathway of complement activation, not specific to Type III hypersensitivity.
D: C2 and C7 are involved in the classical pathway of complement activation but not directly implicated in Type III hypersensitivity reactions.