EXAM 2025/2026 | Comprehensive Review |
Verified Q&A | Pass Guaranteed - A+ Graded
[Part I: Fat-Soluble Vitamins (Questions 1-10)]
Q1: Which of the following is the primary biochemical function of Vitamin A in vision? A. Facilitating
calcium absorption in the retina B. Serving as a component of rhodopsin in rod cells C. Acting as an
antioxidant to prevent cataract formation D. Regulating melanin synthesis in the cone cells
Correct Answer: B
Rationale: Vitamin A (as 11-cis-retinal) is an essential structural component of rhodopsin, the
photopigment in retinal rod cells that enables dark adaptation and low-light vision. [CORRECT]
Q2: A 4-year-old child living in an urban high-rise with limited sun exposure presents with bowed legs,
delayed fontanelle closure, and serum calcium of 7.8 mg/dL. Which vitamin deficiency is most likely
responsible? A. Vitamin A B. Vitamin D C. Vitamin E D. Vitamin K
Correct Answer: B
Rationale: Vitamin D deficiency impairs intestinal calcium and phosphate absorption, leading to
hypocalcemia, defective bone mineralization, and the characteristic skeletal deformities of rickets in
children. [CORRECT]
Q3: Which dietary source provides the most bioavailable form of Vitamin E? A. Fortified breakfast
cereals B. Raw spinach and kale C. Wheat germ oil and sunflower seeds D. Citrus fruits and berries
Correct Answer: C
Rationale: Vitamin E (alpha-tocopherol) is a fat-soluble antioxidant found in highest concentrations in
plant oils, nuts, and seeds, with wheat germ oil and sunflower seeds being among the richest natural
sources. [CORRECT]
, Q4: A 72-year-old male on long-term warfarin therapy for atrial fibrillation is advised to maintain
consistent intake of which vitamin to prevent fluctuations in his INR? A. Vitamin A B. Vitamin D C.
Vitamin E D. Vitamin K
Correct Answer: D
Rationale: Vitamin K is required as a cofactor for the gamma-carboxylation of clotting factors II, VII, IX,
and X; warfarin antagonizes this action, so variable Vitamin K intake directly alters anticoagulant
efficacy. [CORRECT]
Q5: Which clinical presentation is most characteristic of chronic Vitamin A toxicity in adults? A.
Peripheral neuropathy and dermatitis B. Pseudotumor cerebri, hepatomeegaly, and bone pain C.
Hemolytic anemia and retinal degeneration D. Coagulopathy and easy bruising
Correct Answer: B
Rationale: Hypervitaminosis A manifests with increased intracranial pressure (pseudotumor cerebri),
hepatotoxicity, and bone abnormalities due to retinoic acid's effects on osteoclast activity and hepatic
stellate cell activation. [CORRECT]
Q6: Vitamin K-dependent clotting factors synthesized in the liver include which of the following? A.
Factors I, V, and VIII B. Factors II, VII, IX, and X C. Factors XI, XII, and XIII D. Factors III and VI
Correct Answer: B
Rationale: The gamma-carboxylation of glutamate residues on Factors II (prothrombin), VII, IX, and X is
Vitamin K-dependent and essential for their calcium-binding ability and subsequent activation in the
coagulation cascade. [CORRECT]
Q7: A premature infant receiving prolonged parenteral nutrition without lipid supplementation develops
hemolytic anemia and retinopathy. Which vitamin deficiency is most likely? A. Vitamin A B. Vitamin D C.
Vitamin E D. Vitamin K
Correct Answer: C
Rationale: Vitamin E is a lipid-soluble antioxidant that protects erythrocyte membranes and retinal
photoreceptors from oxidative damage; deficiency in preterm infants causes hemolytic anemia and
retinopathy of prematurity due to impaired membrane stability. [CORRECT]