The hexose monophosphate pathway activity increases the RBC source of

Correct Answer: C

Rationale: The correct answer is C: NADPH and reduced glutathione. In the hexose monophosphate pathway, glucose-6-phosphate is converted to ribose-5-phosphate and generates NADPH. NADPH is essential for maintaining cellular redox balance and for reducing oxidized glutathione to its reduced form, which helps protect against oxidative damage in RBCs. Choice A (Glucose and lactic acid) is incorrect because the pathway does not directly produce these compounds. Choice B (2,3-BPG and methemoglobin) is incorrect as these are not products of the hexose monophosphate pathway. Choice D (ATP and other purine metabolites) is incorrect because the main products of the pathway are NADPH and ribose-5-phosphate, not ATP or purine metabolites.

Correct Answer: B

Rationale: The correct answer is B: Koilonychia. Koilonychia is a clinical sign associated with iron deficiency anemia characterized by spoon-shaped nails. This occurs due to the decreased production of hemoglobin, leading to changes in the nail bed. Fever (choice A) is not a typical sign of iron deficiency anemia. Rash (choice C) is not a common manifestation of this condition. Weight gain (choice D) is also not a typical sign, as iron deficiency anemia is more commonly associated with weight loss or failure to thrive. Therefore, choice B is the most appropriate sign to look for in a patient with iron deficiency anemia.

Correct Answer: C

Rationale: The correct answer is C: Disseminated intravascular coagulation (DIC). In septic shock, the body's response can lead to widespread activation of clotting factors, causing both clotting and bleeding. Low platelets and elevated PT/APTT are common in DIC due to consumption of clotting factors and platelets. Thrombotic thrombocytopenic purpura (A) presents with microangiopathic hemolytic anemia, not typical in this case. Hemophilia (B) is a genetic disorder resulting in specific clotting factor deficiencies, not consistent with the patient's presentation. Von Willebrand disease (D) is a deficiency in vWF, leading to mucosal bleeding, not the systemic coagulopathy seen in DIC.

Correct Answer: B

Rationale: The correct answer is B because class II MHC proteins on donor cells are recognized by helper T cells, leading to the activation of cytotoxic T cells which then kill the donor cells. This process is crucial in graft rejection as it triggers an immune response against the foreign cells. Choice A is incorrect because class II MHC proteins are not receptors for interleukin-2. Choice C is incorrect as class II MHC proteins do not induce the production of blocking antibodies. Choice D is incorrect because class II MHC proteins do not induce IgE production, which is involved in allergic reactions, not graft rejection.

Correct Answer: C

Rationale: Complement fixation refers to the binding of complement components by antigen-antibody complexes. This process involves the activation of the complement pathway, leading to the formation of the membrane attack complex and subsequent lysis of target cells. Choice A is incorrect as it describes opsonization, not complement fixation. Choice B is incorrect as it refers to heat inactivation of complement. Choice D is incorrect as it does not involve complement fixation but rather describes the interaction of C3a with mast cells.