The layer of the erythrocyte membrane that is largely responsible for the shape, structure, and deformability of the cell is the:

Correct Answer: C

Rationale: The correct answer is C: Peripheral protein. Peripheral proteins are located on the surface of the erythrocyte membrane and play a crucial role in maintaining cell shape, structure, and deformability. They interact with the cytoskeleton to support the membrane's integrity. Integral proteins (choice A) are embedded within the lipid bilayer but do not directly impact cell shape. Exterior lipids (choice B) are components of the membrane but do not have a primary role in determining cell structure. Interior lipids (choice D) are important for membrane fluidity but do not contribute significantly to cell shape and deformability.

Correct Answer: B

Rationale: The correct answer is B: Auer rods. A bone marrow biopsy in a patient with leukemia may show Auer rods, which are needle-shaped cytoplasmic inclusions found in myeloid cells. Auer rods are characteristic of acute myeloid leukemia. Smudge cells (choice A) are seen in chronic lymphocytic leukemia. Reed-Sternberg cells (choice C) are found in Hodgkin's lymphoma. Lytic lesions (choice D) are seen in multiple myeloma, but are not typically identified on a bone marrow biopsy. Thus, Auer rods are the most likely finding on a bone marrow biopsy in a patient with leukemia.

Correct Answer: C

Rationale: The correct answer is C: patchy, irregular fluorescence of the glomerular basement membrane. In acute glomerulonephritis, there is immune complex deposition in the glomeruli leading to inflammation. The immune complexes contain IgG antibodies, which will bind to the glomerular basement membrane. When stained with fluorescein-conjugated anti-human IgG antibody, the presence of IgG antibodies in the glomerular basement membrane will result in patchy, irregular fluorescence patterns. Choice A is incorrect as there should be fluorescence due to IgG deposition. Choice B is incorrect as the fluorescence pattern is not uniform. Choice D is incorrect as B cells are not typically involved in the pathology of acute glomerulonephritis.

Correct Answer: A

Rationale: The correct answer is A because C3b is not involved in altering vascular permeability. C3b plays a role in promoting phagocytosis by opsonizing pathogens, forming alternative-pathway C3 convertase for amplifying the complement cascade, and forming C5 convertase to initiate the terminal pathway. In contrast, altering vascular permeability is primarily mediated by other factors such as histamine and bradykinin. Therefore, C3b's involvement in altering vascular permeability is not supported by the functions it actually performs in the complement system.

Correct Answer: C

Rationale: The correct answer is C: a cell-mediated response. Poison ivy and poison oak reactions are primarily caused by contact with urushiol, an oil found in these plants. This oil triggers a cell-mediated immune response, involving T cells. T cells release cytokines that lead to inflammation and the characteristic rash. IgG and IgE responses are mainly involved in antibody-mediated immune responses, not in poison ivy reactions. Arthus reaction is a localized immune complex-mediated hypersensitivity reaction, not typically associated with poison ivy or poison oak.