Check out today’s Step 1 Qmax Question Challenge.
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A 44-year-old former alcoholic woman presents with worsening fatigue for the past 2 months. She reports no other symptoms, and physical examination is unremarkable. Laboratory studies reveal a hemoglobin level of 8 g/dL and mean corpuscular volume of 110 μm³. The blood smear shown in the image was obtained as part of her work-up.
Which of the following is the function of the vitamin causing this patient’s condition?
A. Catalyzes γ-carboxylation of glutamic acid residues
B. Hydroxylates prolyl and lysyl residues
C. Increases intestinal calcium and phosphate absorption
D. Makes up the constituents of the visual pigments
E. Transfers single-carbon intermediates
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