1. Which of the following is a fat-soluble vitamin?
Correct Answer: C (Vitamin K)
Vitamins A, D, E, and K are fat-soluble vitamins, whereas Vitamin C and all B-complex vitamins are water-soluble.
Vitamins A, D, E, and K are fat-soluble vitamins, whereas Vitamin C and all B-complex vitamins are water-soluble.
2. What is the chemical name of Vitamin C?
Correct Answer: B (Ascorbic acid)
Vitamin C is chemically known as ascorbic acid. Retinol is Vitamin A, Calciferol is Vitamin D, and Tocopherol is Vitamin E.
Vitamin C is chemically known as ascorbic acid. Retinol is Vitamin A, Calciferol is Vitamin D, and Tocopherol is Vitamin E.
3. Deficiency of which vitamin leads to night blindness (Nyctalopia) and Xerophthalmia?
Correct Answer: A (Vitamin A)
Vitamin A (retinal) forms rhodopsin in rod cells of the retina, which is essential for vision in low-light conditions.
Vitamin A (retinal) forms rhodopsin in rod cells of the retina, which is essential for vision in low-light conditions.
4. Which mineral is an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3)?
Correct Answer: C (Iodine)
Iodine is required by the thyroid gland to synthesize thyroid hormones; its deficiency leads to goiter.
Iodine is required by the thyroid gland to synthesize thyroid hormones; its deficiency leads to goiter.
5. Scurvy, characterized by bleeding gums and poor wound healing, is caused by a deficiency of:
Correct Answer: B (Vitamin C)
Vitamin C is a cofactor for prolyl and lysyl hydroxylases required for collagen biosynthesis and cross-linking.
Vitamin C is a cofactor for prolyl and lysyl hydroxylases required for collagen biosynthesis and cross-linking.
6. Which vitamin is synthesized in the human skin upon exposure to ultraviolet B (UVB) sunlight?
Correct Answer: B (Vitamin D)
UVB radiation converts 7-dehydrocholesterol in the skin to cholecalciferol (Vitamin D3).
UVB radiation converts 7-dehydrocholesterol in the skin to cholecalciferol (Vitamin D3).
7. Rickets in children and Osteomalacia in adults are primarily caused by a deficiency of:
Correct Answer: A (Vitamin D)
Vitamin D regulates intestinal calcium and phosphate absorption necessary for proper bone mineralization.
Vitamin D regulates intestinal calcium and phosphate absorption necessary for proper bone mineralization.
8. Which metal ion is present at the center of the corrin ring in Vitamin B12 (Cobalamin)?
Correct Answer: C (Cobalt)
Vitamin B12 contains a coordinated cobalt ion, which gives it its biological activity and chemical name (cobalamin).
Vitamin B12 contains a coordinated cobalt ion, which gives it its biological activity and chemical name (cobalamin).
9. Beriberi is a deficiency disease associated with which B-complex vitamin?
Correct Answer: A (Vitamin B1 (Thiamine))
Thiamine deficiency impairs carbohydrate metabolism and ATP production, leading to neurological and cardiovascular symptoms (Beriberi).
Thiamine deficiency impairs carbohydrate metabolism and ATP production, leading to neurological and cardiovascular symptoms (Beriberi).
10. Pellagra is characterized by the 3 Ds (Dermatitis, Diarrhea, Dementia) and is caused by a deficiency of:
Correct Answer: C (Vitamin B3 (Niacin))
Niacin (nicotinic acid) is a precursor for NAD/NADP; deficiency causes severe metabolic disturbances manifested as Pellagra.
Niacin (nicotinic acid) is a precursor for NAD/NADP; deficiency causes severe metabolic disturbances manifested as Pellagra.
11. Which vitamin plays an indispensable role in blood clotting by facilitating post-translational carboxylation of clotting factors (II, VII, IX, X)?
Correct Answer: D (Vitamin K)
Vitamin K acts as a cofactor for gamma-glutamyl carboxylase to activate clotting factors for calcium binding.
Vitamin K acts as a cofactor for gamma-glutamyl carboxylase to activate clotting factors for calcium binding.
12. Which mineral is the most abundant cation found in the extracellular fluid of the human body?
Correct Answer: A (Sodium (Na+))
Sodium is the principal extracellular cation responsible for osmotic balance, blood volume, and nerve impulses.
Sodium is the principal extracellular cation responsible for osmotic balance, blood volume, and nerve impulses.
13. Which mineral is the principal intracellular cation in human cells?
Correct Answer: B (Potassium)
Potassium (K+) is the primary intracellular cation, vital for maintaining resting membrane potential and cellular osmolarity.
Potassium (K+) is the primary intracellular cation, vital for maintaining resting membrane potential and cellular osmolarity.
14. Pernicious anemia is caused by impaired absorption of Vitamin B12 due to a lack of which gastric factor?
Correct Answer: B (Intrinsic Factor)
Intrinsic factor, secreted by gastric parietal cells, binds Vitamin B12 to allow its absorption in the terminal ileum.
Intrinsic factor, secreted by gastric parietal cells, binds Vitamin B12 to allow its absorption in the terminal ileum.
15. Deficiency of which vitamin in early pregnancy increases the risk of neural tube defects (such as spina bifida)?
Correct Answer: C (Vitamin B9 (Folate / Folic acid))
Folate is crucial for DNA synthesis and rapid cell division in the developing neural tube of the embryo.
Folate is crucial for DNA synthesis and rapid cell division in the developing neural tube of the embryo.
16. What is the active hormonal form of Vitamin D synthesized by the kidneys?
Correct Answer: C (1,25-dihydroxycholecalciferol (Calcitriol))
Calcitriol is the fully activated form of Vitamin D produced via 1-alpha-hydroxylase in renal tubules.
Calcitriol is the fully activated form of Vitamin D produced via 1-alpha-hydroxylase in renal tubules.
17. Which essential mineral is the central atom in hemoglobin and myoglobin?
Correct Answer: A (Iron (Fe))
Iron sits coordinated at the center of the porphyrin ring to bind and transport oxygen reversibly.
Iron sits coordinated at the center of the porphyrin ring to bind and transport oxygen reversibly.
18. Cheilosis (cracking at the corners of the mouth) and glossitis are typical symptoms of a deficiency in:
Correct Answer: B (Vitamin B2 (Riboflavin))
Riboflavin deficiency (ariboflavinosis) causes angular cheilitis, glossitis (magenta tongue), and pharyngitis.
Riboflavin deficiency (ariboflavinosis) causes angular cheilitis, glossitis (magenta tongue), and pharyngitis.
19. Wilson’s disease is a genetic metabolic disorder characterized by excessive accumulation of which mineral in organs?
Correct Answer: B (Copper)
Wilson’s disease is caused by mutations in the ATP7B gene, causing toxic copper accumulation in the liver, brain, and eyes (Kayser-Fleischer rings).
Wilson’s disease is caused by mutations in the ATP7B gene, causing toxic copper accumulation in the liver, brain, and eyes (Kayser-Fleischer rings).
20. Hemochromatosis is an inherited disorder characterized by toxic over-absorption and tissue storage of:
Correct Answer: A (Iron)
Hemochromatosis causes excessive iron buildup, leading to liver cirrhosis, bronze diabetes, and heart failure.
Hemochromatosis causes excessive iron buildup, leading to liver cirrhosis, bronze diabetes, and heart failure.
21. Which vitamin functions primarily as a potent lipid-soluble chain-breaking antioxidant in cell membranes?
Correct Answer: C (Vitamin E (Tocopherol))
Vitamin E scavenges reactive oxygen species (ROS) to protect polyunsaturated fatty acids in membranes from lipid peroxidation.
Vitamin E scavenges reactive oxygen species (ROS) to protect polyunsaturated fatty acids in membranes from lipid peroxidation.
22. Which trace mineral is a critical component of antioxidant enzyme glutathione peroxidase?
Correct Answer: B (Selenium)
Selenium is incorporated as selenocysteine into glutathione peroxidase and thioredoxin reductase.
Selenium is incorporated as selenocysteine into glutathione peroxidase and thioredoxin reductase.
23. Which B-vitamin is also known as Pantothenic acid and forms a vital component of Coenzyme A (CoA)?
Correct Answer: B (Vitamin B5)
Vitamin B5 (pantothenic acid) is required for synthesizing Coenzyme A and acyl-carrier protein (ACP).
Vitamin B5 (pantothenic acid) is required for synthesizing Coenzyme A and acyl-carrier protein (ACP).
24. What is the chemical name of Vitamin B7, which serves as a coenzyme in carboxylation reactions?
Correct Answer: B (Biotin)
Biotin (Vitamin B7 or Vitamin H) transfers CO2 in carboxylase enzyme pathways (e.g., pyruvate carboxylase).
Biotin (Vitamin B7 or Vitamin H) transfers CO2 in carboxylase enzyme pathways (e.g., pyruvate carboxylase).
25. Consumption of raw egg whites can induce Biotin deficiency because raw egg whites contain:
Correct Answer: A (Avidin)
Avidin binds irreversibly to biotin with extremely high affinity, preventing its intestinal absorption.
Avidin binds irreversibly to biotin with extremely high affinity, preventing its intestinal absorption.
26. Which mineral enhances the action of insulin and facilitates cellular glucose uptake?
Correct Answer: A (Chromium)
Chromium is part of the glucose tolerance factor (GTF), potentiating the physiological response of insulin receptors.
Chromium is part of the glucose tolerance factor (GTF), potentiating the physiological response of insulin receptors.
27. Which mineral is integrated into bone and teeth as hydroxyapatite crystals [Ca10(PO4)6(OH)2]?
Correct Answer: B (Calcium and Phosphorus)
Around 99% of body calcium and 85% of body phosphorus are stored in bone mineral as hydroxyapatite.
Around 99% of body calcium and 85% of body phosphorus are stored in bone mineral as hydroxyapatite.
28. Which trace mineral is vital for taste acuity (gustation), wound healing, and immune cell proliferation?
Correct Answer: B (Zinc)
Zinc is a cofactor for over 300 enzymes (including carbonic anhydrase and DNA polymerases); deficiency causes hypogeusia (loss of taste) and poor healing.
Zinc is a cofactor for over 300 enzymes (including carbonic anhydrase and DNA polymerases); deficiency causes hypogeusia (loss of taste) and poor healing.
29. What condition is caused by chronic excessive intake of fluoride, resulting in mottling of dental enamel?
Correct Answer: A (Dental Fluorosis)
Fluorosis occurs due to hyper-mineralization disturbances during tooth development from excessive fluoride ingestion.
Fluorosis occurs due to hyper-mineralization disturbances during tooth development from excessive fluoride ingestion.
30. Vitamin B6 (Pyridoxine) is converted into Pyridoxal Phosphate (PLP), which is an essential coenzyme for:
Correct Answer: A (Transamination and amino acid metabolism)
PLP acts as a critical cofactor for aminotransferases (transaminases), decarboxylases, and racemoses in amino acid metabolism.
PLP acts as a critical cofactor for aminotransferases (transaminases), decarboxylases, and racemoses in amino acid metabolism.
31. What is the plant dietary precursor (provitamin) of Vitamin A?
Correct Answer: B (Beta-Carotene)
Beta-carotene is cleaved enzymatically in the intestinal mucosa by beta-carotene dioxygenase to yield two molecules of retinal.
Beta-carotene is cleaved enzymatically in the intestinal mucosa by beta-carotene dioxygenase to yield two molecules of retinal.
32. Which mineral is a cofactor for the ATP-synthesizing enzymes and stabilizes ATP phosphate groups?
Correct Answer: A (Magnesium (Mg2+))
Biologically active ATP exists largely as an Mg-ATP2- chelate; magnesium is required by all kinase enzymes.
Biologically active ATP exists largely as an Mg-ATP2- chelate; magnesium is required by all kinase enzymes.
33. Wernicke-Korsakoff syndrome, frequently seen in chronic alcoholics, results from a severe deficiency of:
Correct Answer: C (Vitamin B1 (Thiamine))
Alcohol impairs thiamine absorption and utilization, causing acute encephalopathy and chronic amnestic syndrome.
Alcohol impairs thiamine absorption and utilization, causing acute encephalopathy and chronic amnestic syndrome.
34. Which vitamin is prescribed alongside the antitubercular drug Isoniazid to prevent peripheral neuropathy?
Correct Answer: A (Vitamin B6 (Pyridoxine))
Isoniazid binds to pyridoxine and promotes its renal excretion, causing secondary neuropathy unless supplemented.
Isoniazid binds to pyridoxine and promotes its renal excretion, causing secondary neuropathy unless supplemented.
35. Tetany (involuntary muscle spasm) can be triggered by acute low blood levels of which ionized mineral?
Correct Answer: A (Calcium (Hypocalcemia))
Low extracellular ionized calcium increases neuronal membrane permeability to sodium ions, resulting in neuromuscular hyperexcitability and tetany.
Low extracellular ionized calcium increases neuronal membrane permeability to sodium ions, resulting in neuromuscular hyperexcitability and tetany.
36. Which amino acid can serve as an endogenous precursor for the synthesis of Vitamin B3 (Niacin)?
Correct Answer: B (Tryptophan)
In humans, approximately 60 mg of dietary tryptophan can be converted into 1 mg of niacin via the kynurenine pathway.
In humans, approximately 60 mg of dietary tryptophan can be converted into 1 mg of niacin via the kynurenine pathway.
37. Vitamin B12 and Folate deficiency both lead to which type of anemia?
Correct Answer: B (Megaloblastic (Macrocytic) anemia)
Defects in DNA synthesis arrest erythrocyte nuclear maturation while cytoplasmic growth continues, forming large erythroblasts (megaloblasts).
Defects in DNA synthesis arrest erythrocyte nuclear maturation while cytoplasmic growth continues, forming large erythroblasts (megaloblasts).
38. Keshan disease, an endemic cardiomyopathy, is linked to a nutritional deficiency in which trace mineral?
Correct Answer: A (Selenium)
Keshan disease occurs in regions with selenium-poor soils and is prevented by sodium selenite supplementation.
Keshan disease occurs in regions with selenium-poor soils and is prevented by sodium selenite supplementation.
39. Which of the following forms of Vitamin K is synthesized by intestinal microbiota?
Correct Answer: B (Menaquinone (Vitamin K2))
Vitamin K1 comes from green leafy plants, while Vitamin K2 is produced by gut bacterial flora.
Vitamin K1 comes from green leafy plants, while Vitamin K2 is produced by gut bacterial flora.
40. Which hormone increases renal reabsorption and intestinal absorption of calcium when blood calcium drops?
Correct Answer: A (Parathyroid Hormone (PTH))
PTH restores serum calcium by stimulating osteoclasts, increasing renal tubular Ca2+ retention, and activating Vitamin D to Calcitriol.
PTH restores serum calcium by stimulating osteoclasts, increasing renal tubular Ca2+ retention, and activating Vitamin D to Calcitriol.
41. Bitot’s spots (keratinized patches on the conjunctiva) are a clinical sign of:
Correct Answer: A (Vitamin A deficiency)
Bitot’s spots are foamy superficial triangular lesions on the scleral conjunctiva characteristic of xerophthalmia in Vitamin A deficiency.
Bitot’s spots are foamy superficial triangular lesions on the scleral conjunctiva characteristic of xerophthalmia in Vitamin A deficiency.
42. What is the storage form of iron inside cells?
Correct Answer: B (Ferritin)
Ferritin stores intracellular non-toxic ferric iron, whereas Transferrin is the main iron transport protein in blood plasma.
Ferritin stores intracellular non-toxic ferric iron, whereas Transferrin is the main iron transport protein in blood plasma.
43. Menkes “kinky hair” disease is an X-linked recessive disorder caused by defective absorption and transport of:
Correct Answer: B (Copper)
Menkes disease is caused by mutations in ATP7A, leading to severe copper deficiency, brittle kinky hair, and neurodegeneration.
Menkes disease is caused by mutations in ATP7A, leading to severe copper deficiency, brittle kinky hair, and neurodegeneration.
44. Which enzyme uses Molybdenum as an essential cofactor to convert xanthine into uric acid?
Correct Answer: A (Xanthine oxidase)
Xanthine oxidase contains a molybdopterin cofactor essential for purine catabolism into uric acid.
Xanthine oxidase contains a molybdopterin cofactor essential for purine catabolism into uric acid.
45. Hypervitaminosis (toxic overload from excessive supplement intake) is most common with which class of vitamins?
Correct Answer: B (Fat-soluble vitamins)
Because fat-soluble vitamins (A and D especially) accumulate in adipose tissue and liver rather than being excreted rapidly in urine, they are far more prone to toxicity.
Because fat-soluble vitamins (A and D especially) accumulate in adipose tissue and liver rather than being excreted rapidly in urine, they are far more prone to toxicity.
46. Which vitamin is also known as the anti-sterility factor in animal studies?
Correct Answer: C (Vitamin E)
Tocopherol derives from Greek *tokos* (childbirth) and *pherein* (to bear) because its deficiency causes reproductive failure in rodents.
Tocopherol derives from Greek *tokos* (childbirth) and *pherein* (to bear) because its deficiency causes reproductive failure in rodents.
47. Spoon-shaped concave nails (Koilonychia) are a characteristic diagnostic sign of:
Correct Answer: A (Iron deficiency anemia)
Severe chronic iron deficiency causes thinning and dish-shaped deformity of fingernails (Koilonychia).
Severe chronic iron deficiency causes thinning and dish-shaped deformity of fingernails (Koilonychia).
48. Which mineral is required as a structural cofactor for Superoxide Dismutase 1 (SOD1) in the cytoplasm alongside Copper?
Correct Answer: A (Zinc (Cu/Zn-SOD))
Cytosolic SOD contains both copper (catalytic role) and zinc (structural role) to neutralize superoxide radicals.
Cytosolic SOD contains both copper (catalytic role) and zinc (structural role) to neutralize superoxide radicals.
49. What condition results from severe sodium deficiency or excessive water retention, leading to low serum sodium concentrations?
Correct Answer: B (Hyponatremia)
Hyponatremia is defined by serum sodium levels below 135 mmol/L, causing cellular edema, headache, and confusion.
Hyponatremia is defined by serum sodium levels below 135 mmol/L, causing cellular edema, headache, and confusion.
50. Flavin Adenine Dinucleotide (FAD) and Flavin Mononucleotide (FMN) are biologically active coenzyme derivatives of:
Correct Answer: B (Vitamin B2 (Riboflavin))
Riboflavin is phosphorylated to form FMN and FAD, which act as prosthetic electron carriers in the Krebs cycle and oxidative phosphorylation.
Riboflavin is phosphorylated to form FMN and FAD, which act as prosthetic electron carriers in the Krebs cycle and oxidative phosphorylation.