The enzyme deficiency in the Embden-Meyerhof pathway that is responsible for most cases of nonspherocytic hemolytic anemia is:

Correct Answer: C

Rationale: The correct answer is C: Pyruvate Kinase. This enzyme deficiency in the Embden-Meyerhof pathway leads to the accumulation of intermediates, causing red blood cell damage and hemolytic anemia. Pyruvate Kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate, a crucial step in glycolysis. In contrast, choices A, B, and D are not directly related to the final step of glycolysis and do not lead to the accumulation of intermediates causing hemolytic anemia. Hexokinase is involved in the initial step of glycolysis, Phosphofructokinase in the committed step, and Glyceraldehyde 3-Phosphate Dehydrogenase in the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate.

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.

Correct Answer: D

Rationale: The correct answer is D: indirect fluorescent-antibody test. This method is the best for demonstrating IgG on the glomerular basement membrane in kidney tissue. It involves applying a fluorescent-tagged anti-IgG antibody, which specifically binds to IgG on the tissue section, producing a visible fluorescent signal under a microscope. This technique allows for precise localization and visualization of IgG deposition. A: precipitin test and C: agglutination test are not suitable for detecting IgG specifically on tissue sections. B: complement fixation test is not commonly used for direct visualization of IgG in tissues. The indirect fluorescent-antibody test is the most sensitive and specific method for detecting IgG in tissue samples.