A 30 year old patient had presented with fever and posterior cervical lymphadenopathy over the past two years. Which is the most probably causative organism?

Correct Answer: C

Rationale: The correct answer is C: Trypanosoma brucei gambiense. This is the most likely causative organism because the patient's presentation of fever and posterior cervical lymphadenopathy is consistent with African trypanosomiasis, also known as sleeping sickness, which is caused by T. brucei gambiense. This parasite is transmitted by the tsetse fly in sub-Saharan Africa. The other choices (A, B, D) are not the correct causative organism for African trypanosomiasis and do not match the clinical presentation described in the question. Trypanosoma cruzi causes Chagas disease, Trypanosoma brucei rhodesiense causes a more acute form of African trypanosomiasis, and Leishmania donovani causes visceral leishmaniasis, which typically presents with splenomegaly and hepatomegaly rather than posterior cervical lymphadenopathy.

Correct Answer: B

Rationale: The correct answer is B: Reduction of glutathione. In the hexose monophosphate pathway (HMP), NADPH is generated, which serves as a reducing agent. This NADPH is crucial for reducing oxidized glutathione back to its reduced form, maintaining cellular antioxidant defense. This process helps to protect cells from oxidative damage and maintain redox balance. Now, let's summarize why the other choices are incorrect: A: Synthesis of fatty acids - NADPH is indeed involved in fatty acid synthesis, but in the context of red blood cells, the primary role of NADPH is in reducing glutathione. C: Formation of ATP - NADPH is not directly involved in ATP synthesis. ATP is primarily produced through processes like glycolysis and oxidative phosphorylation. D: Removal of oxygen radicals - While NADPH indirectly contributes to the removal of oxygen radicals through its role in reducing glutathione, it is not the primary function of NAD

Correct Answer: A

Rationale: The correct answer is A because iron absorption primarily occurs in the duodenum and upper jejunum of the small intestine. This is where iron is absorbed into the bloodstream and utilized by the body. Absorption in the large intestine, as stated in choice A, is incorrect. Intrinsic factor, mentioned in choice B, is necessary for the absorption of vitamin B12, not iron. Ascorbic acid actually enhances iron absorption, so choice C is incorrect. Absorption in hereditary hemochromatosis, as in choice D, is increased due to a genetic mutation causing excessive iron absorption, not with oral iron supplements.

Correct Answer: B

Rationale: The correct answer is B: Absolute lymphocytes. In CLL, the most important diagnostic criterion is an absolute lymphocyte count of more than 5,000 cells per microliter in the peripheral blood. This is a key feature of CLL and distinguishes it from other conditions. Hypogammaglobulinemia (choice A) may occur in CLL but is not as specific for diagnosis. Male predominance (choice C) is a general characteristic of CLL but is not a diagnostic criterion. Presence of enlarged lymph nodes (choice D) is a common manifestation of CLL but not the most important criteria for diagnosis.

Correct Answer: D

Rationale: The correct answer is D because heparin binds to antithrombin III, enhancing its ability to inactivate thrombin. This prevents the conversion of fibrinogen to fibrin, thereby inhibiting blood clot formation. Choice A is incorrect because vitamin K-dependent clotting factors are not directly affected by heparin. Choice B is incorrect because heparin does not prevent the activation of platelets, rather it affects the coagulation cascade. Choice C is incorrect as heparin does not directly prevent platelet aggregation, which is more related to antiplatelet agents like aspirin.