Vitamins and Minerals Physiology Practice Questions
40 free Vitamins and Minerals Physiology practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Vitamin B12 absorption in the gastrointestinal tract primarily requires:
- A Bile salts
- B Intrinsic factor
- C Pancreatic lipase
- D Sodium-glucose cotransporter
Correct answer: Intrinsic factor
Vitamin B12 binds to intrinsic factor secreted by gastric parietal cells. This complex is absorbed in the terminal ileum.
Which vitamin is absorbed mainly in the jejunum as micelles with dietary fat?
- A Vitamin C
- B Vitamin B1
- C Vitamin A
- D Vitamin B6
Correct answer: Vitamin A
Vitamin A is fat-soluble and absorbed with dietary fats in the jejunum. Bile salts are required to form micelles.
Deficiency of which vitamin most directly impairs calcium absorption?
- A Vitamin A
- B Vitamin C
- C Vitamin D
- D Vitamin K
Correct answer: Vitamin D
Vitamin D increases intestinal calcium absorption by upregulating calcium-binding proteins. Deficiency leads to reduced calcium uptake.
Iron absorption occurs predominantly in the:
- A Duodenum
- B Ileum
- C Jejunum
- D Stomach and proximal colon
Correct answer: Duodenum
Iron is absorbed mainly in the duodenum. The acidic environment facilitates conversion to the ferrous form for absorption.
Which factor enhances non-heme iron absorption in the intestine?
- A Dietary calcium salts
- B Phytates from grains
- C Vitamin C
- D Tannins from tea
Correct answer: Vitamin C
Vitamin C reduces ferric iron to ferrous iron, enhancing absorption. It also forms soluble complexes with iron.
Vitamin K is essential for the synthesis of:
- A Structural collagen fibers
- B Clotting factors
- C Circulating hemoglobin
- D Primary bile acids
Correct answer: Clotting factors
Vitamin K is required for gamma-carboxylation of clotting factors II, VII, IX, and X. Deficiency leads to bleeding tendencies.
Which mineral is primarily absorbed in the small intestine via active transport regulated by vitamin D?
- A Iron
- B Calcium
- C Magnesium
- D Phosphate
Correct answer: Calcium
Calcium absorption in the small intestine is enhanced by vitamin D. Active transport predominates when dietary calcium is low.
Malabsorption of fat-soluble vitamins is most likely in:
- A Celiac disease
- B Cholestasis
- C Achlorhydria
- D IBS
Correct answer: Cholestasis
Cholestasis reduces bile delivery to the intestine. This impairs micelle formation and fat-soluble vitamin absorption.
Which vitamin deficiency is associated with megaloblastic anemia due to impaired DNA synthesis?
- A Vitamin B12
- B Vitamin A (retinol)
- C Vitamin D (calciferol)
- D Vitamin E (tocopherol)
Correct answer: Vitamin B12
Vitamin B12 deficiency disrupts DNA synthesis in rapidly dividing cells. This results in megaloblastic anemia.
Folate absorption occurs primarily in the:
- A Stomach
- B Duodenum
- C Jejunum
- D Ileum
Correct answer: Jejunum
Folate is absorbed mainly in the jejunum. Deficiency can occur with malabsorption or increased requirements.
Which mineral deficiency most directly causes hypochromic microcytic anemia?
- A Calcium
- B Iron
- C Zinc
- D Copper
Correct answer: Iron
Iron deficiency reduces hemoglobin synthesis. This leads to microcytic, hypochromic anemia.
Vitamin C deficiency most commonly results in:
- A Rickets
- B Scurvy
- C Night blindness
- D Bleeding diathesis due to clotting factor deficiency
Correct answer: Scurvy
Vitamin C is required for collagen synthesis. Deficiency causes scurvy with bleeding gums and poor wound healing.
Which vitamin acts as an antioxidant protecting cell membranes from oxidative damage?
- A Vitamin A
- B Vitamin D
- C Vitamin E
- D Vitamin K
Correct answer: Vitamin E
Vitamin E is a fat-soluble antioxidant. It protects polyunsaturated fatty acids in cell membranes.
Zinc deficiency most directly impairs:
- A Calcium absorption from the gut
- B Wound healing and taste
- C Bile secretion by the liver
- D Iron transport in plasma
Correct answer: Wound healing and taste
Zinc is required for numerous enzymes involved in tissue repair and taste perception. Deficiency delays wound healing.
Which vitamin requires pancreatic enzymes for optimal absorption?
- A Vitamin C
- B Vitamin B12
- C Vitamin A
- D Vitamin B6
Correct answer: Vitamin A
Pancreatic enzymes facilitate fat digestion, enabling absorption of vitamin A. Pancreatic insufficiency can cause deficiency.
Copper absorption occurs primarily in the:
- A Stomach and duodenum
- B The jejunum and nowhere else
- C Ileum
- D Colon
Correct answer: Stomach and duodenum
Copper is absorbed mainly in the stomach and proximal duodenum. It is essential for iron metabolism and enzyme function.
Which condition most directly impairs vitamin B12 absorption?
- A Pancreatitis
- B Pernicious anemia
- C Celiac disease
- D Short bowel syndrome
Correct answer: Pernicious anemia
Pernicious anemia results from lack of intrinsic factor. This prevents vitamin B12 absorption in the ileum.
Magnesium absorption in the intestine occurs primarily by:
- A Active transport only
- B Passive paracellular diffusion
- C Endocytosis
- D Carrier-mediated cotransport with glucose
Correct answer: Passive paracellular diffusion
Magnesium is absorbed mainly by passive paracellular diffusion. Absorption increases with higher luminal concentrations.
Which vitamin deficiency leads to night blindness?
- A Vitamin D
- B Vitamin A
- C Vitamin E
- D Vitamin K
Correct answer: Vitamin A
Vitamin A is required for rhodopsin formation in the retina. Deficiency impairs low-light vision.
Chronic diarrhea most commonly leads to deficiency of which mineral?
- A Sodium
- B Zinc
- C Iron
- D Calcium
Correct answer: Zinc
Zinc is lost in gastrointestinal secretions and poorly absorbed during diarrhea. Deficiency is common with chronic GI losses.
Which of the following transport proteins is responsible for the apical uptake of ferrous iron (Fe2+) into the enterocytes of the duodenum?
- A Ferroportin (basolateral exporter)
- B Transferrin (plasma iron carrier)
- C Ferritin (intracellular iron store)
- D Divalent Metal Transporter 1 (DMT1)
Correct answer: Divalent Metal Transporter 1 (DMT1)
DMT1 is the primary transporter for non-heme iron across the apical membrane of enterocytes. It specifically transports iron in its reduced, ferrous state.
A deficiency in which vitamin is most likely to lead to an accumulation of homocysteine and a secondary deficiency of folate due to the 'methyl-folate trap'?
- A Vitamin B12 (Cobalamin)
- B Vitamin B6 (Pyridoxine)
- C Vitamin C (Ascorbic acid)
- D Vitamin K (Phylloquinone)
Correct answer: Vitamin B12 (Cobalamin)
Vitamin B12 is a cofactor for methionine synthase; without it, 5-methyltetrahydrofolate cannot donate its methyl group, leading to trapped folate and high homocysteine.
Which of the following fat-soluble vitamins is synthesized by intestinal bacteria and serves as a critical cofactor for the gamma-carboxylation of clotting factors?
- A Vitamin A
- B Vitamin D
- C Vitamin E
- D Vitamin K
Correct answer: Vitamin K
Vitamin K is essential for the post-translational modification of factors II, VII, IX, and X, allowing them to bind calcium and participate in the clotting cascade.
Which specific region of the gastrointestinal tract is the primary site for the absorption of Vitamin B12-Intrinsic Factor complexes?
- A Duodenum
- B Jejunum
- C Terminal ileum
- D Ascending colon
Correct answer: Terminal ileum
The terminal ileum contains specialized receptors (cubilin) that recognize and internalize the complex formed by Vitamin B12 and Intrinsic Factor.
Which dietary factor is known to significantly inhibit the absorption of non-heme iron by forming insoluble complexes in the gut?
- A Ascorbic acid
- B Citric acid
- C Phylloquinone
- D Phytic acid
Correct answer: Phytic acid
Phytates (found in grains and legumes) and polyphenols (in tea/coffee) bind to iron and prevent its absorption, whereas Vitamin C enhances it.
The absorption of dietary Calcium in the small intestine is stimulated by 1,25-dihydroxyvitamin D3, which increases the synthesis of which intracellular protein?
- A Calbindin
- B Albumin
- C Hemoglobin
- D Intrinsic Factor
Correct answer: Calbindin
Calbindin acts as an intracellular shuttle that ferries calcium across the enterocyte from the apical to the basolateral membrane, preventing high free calcium levels.
Which vitamin functions as a coenzyme in the hydroxylation of proline and lysine residues during collagen synthesis?
- A Thiamine (B1)
- B Riboflavin (B2)
- C Ascorbic acid (C)
- D Nicotinic acid (B3)
Correct answer: Ascorbic acid (C)
Vitamin C is a vital antioxidant that maintains iron in the ferrous state for prolyl and lysyl hydroxylase, which are required for stable collagen triple-helix formation.
Which trace mineral is a central component of the enzyme glutathione peroxidase, protecting cells against oxidative cytosol damage?
- A Zinc
- B Copper
- C Selenium
- D Manganese
Correct answer: Selenium
Selenium is an essential constituent of selenoproteins like glutathione peroxidase, which reduces hydrogen peroxide to water.
A patient presents with dermatitis, diarrhea, and dementia (the 3 Ds). This classic triad suggests a deficiency in which vitamin?
- A B1 (Thiamine)
- B B2 (Riboflavin)
- C B3 (Niacin/PP)
- D B6 (Pyridoxine)
Correct answer: B3 (Niacin/PP)
Pellagra is caused by a deficiency of Niacin (Vitamin B3) or its precursor tryptophan, leading to the characteristic '3 Ds' clinical presentation.
Which of the following vitamins is primarily transported from the enterocyte into the lymphatic system via chylomicrons?
- A Vitamin B1 (Thiamine)
- B Vitamin B12 (Cobalamin)
- C Folic acid (Vitamin B9)
- D Vitamin E (Tocopherol)
Correct answer: Vitamin E (Tocopherol)
As a fat-soluble vitamin, Vitamin E is packaged into chylomicrons along with triglycerides and cholesterol for transport through the lacteals.
Wernicke-Korsakoff syndrome, often seen in chronic alcoholism, is a direct result of a deficiency in:
- A Thiamine (B1)
- B Niacin (B3)
- C Pantothenic acid (B5)
- D Biotin (B7)
Correct answer: Thiamine (B1)
Alcohol interferes with thiamine absorption and utilization. Thiamine is a critical cofactor for glucose metabolism in the brain.
Which mineral is required for the synthesis of thyroid hormones (T3 and T4)?
- A Iron
- B Magnesium
- C Zinc
- D Iodine
Correct answer: Iodine
Iodine is captured by the thyroid gland and attached to thyroglobulin to form the precursors of active thyroid hormones.
Deficiency of which vitamin during early pregnancy is strongly associated with the development of neural tube defects like spina bifida?
- A Vitamin A
- B Vitamin D
- C Vitamin B12
- D Folate (B9)
Correct answer: Folate (B9)
Folate is essential for DNA synthesis and cell division; adequate levels are critical during the first few weeks of gestation for proper neural tube closure.
Which hormone, secreted by the liver in response to high iron stores, acts as the master regulator of iron homeostasis by degrading ferroportin?
- A Hepcidin
- B Erythropoietin
- C Ferritin
- D Gastrin
Correct answer: Hepcidin
Hepcidin inhibits iron release from enterocytes and macrophages by binding to and inducing the internalization of the iron exporter ferroportin.
What is the primary mechanism for the intestinal absorption of dietary Zinc?
- A Active transport via ZIP4 transporters
- B Simple diffusion through the lipid bilayer
- C Binding to intrinsic factor
- D Facilitated diffusion through SGLT-1
Correct answer: Active transport via ZIP4 transporters
ZIP4 is the major apical transporter for zinc in the small intestine. Mutations in this transporter lead to acrodermatitis enteropathica.
Which vitamin serves as a precursor for the visual pigment rhodopsin?
- A Vitamin A (as Retinol)
- B Vitamin B2 (Riboflavin)
- C Vitamin D (Calciferol)
- D Vitamin E (Tocopherol)
Correct answer: Vitamin A (as Retinol)
11-cis-retinal, a derivative of Vitamin A, combines with the protein opsin to form rhodopsin, the light-sensitive pigment in rod cells.
Which water-soluble vitamin is unique because it can be stored in the liver for several years?
- A Vitamin C
- B Pantothenic acid
- C Vitamin B12
- D Biotin
Correct answer: Vitamin B12
Unlike most water-soluble vitamins that are excreted quickly, the liver maintains significant stores of B12, which is why deficiency takes years to develop.
The absorption of Magnesium occurs throughout the small intestine, but primarily in the ileum via which mechanism?
- A Primary active transport
- B Paracellular passive diffusion
- C Endocytosis
- D SGLT-mediated active cotransport
Correct answer: Paracellular passive diffusion
The bulk of magnesium absorption (about 80-90%) occurs via the paracellular route, driven by an electrochemical gradient, though transcellular transport also exists.
Which vitamin is required as a cofactor for the enzyme Pyruvate Dehydrogenase and Alpha-ketoglutarate dehydrogenase in the TCA cycle?
- A Pyridoxine (B6)
- B Thiamine (B1)
- C Vitamin K
- D Vitamin D
Correct answer: Thiamine (B1)
Thiamine pyrophosphate (TPP) is the active form of B1 and is essential for decarboxylation reactions in energy metabolism.
Which mineral deficiency is associated with impaired wound healing, loss of taste (hypogeusia), and delayed growth?
- A Copper
- B Iron
- C Zinc
- D Fluoride
Correct answer: Zinc
Zinc is involved in hundreds of enzymatic reactions, including those for DNA polymerase and protein synthesis, making it vital for rapidly dividing cells.