CSS - PMS - CCE - PCS - General Science
Vitamins
Which food is generally an excellent source of vitamin C?
A. Guava
B. Refined white rice
C. Butter
D. Table salt
Correct Answer: A
A is correct because guava is especially rich in vitamin C; many citrus fruits, peppers and fresh vegetables are also good sources.
CSS - PMS - CCE - PCS - General Science
Vitamins
Poor wound healing and bleeding gums in vitamin C deficiency are mainly related to defective:
A. Collagen synthesis
B. Vitamin D activation
C. Coagulation factor gamma-carboxylation
D. Rhodopsin formation
Correct Answer: A
A is correct because vitamin C deficiency impairs collagen formation, weakening capillaries, gums and connective tissue.
CSS - PMS - CCE - PCS - General Science
Vitamins
Vitamin C enhances intestinal absorption of which mineral by reducing it to a more absorbable form?
A. Non-heme iron
B. Sodium
C. Potassium
D. Iodine
Correct Answer: A
A is correct because vitamin C reduces ferric iron to ferrous iron and forms soluble complexes, improving non-heme iron absorption.
CSS - PMS - CCE - PCS - General Science
Vitamins
Vitamin C is important in collagen synthesis because it supports hydroxylation of:
A. Proline and lysine residues
B. Glycine only
C. Tryptophan only
D. Methionine only
Correct Answer: A
A is correct because ascorbate is required by prolyl and lysyl hydroxylases during collagen maturation.
CSS - PMS - CCE - PCS - General Science
Vitamins
Vitamin C is chemically known as:
A. Ascorbic acid
B. Folic acid
C. Pantothenic acid
D. Nicotinic acid
Correct Answer: A
A is correct. Vitamin C is ascorbic acid.
CSS - PMS - CCE - PCS - General Science
Vitamins
Body stores of vitamin B12 are relatively large, so deficiency may take years to appear after intake stops. The main storage organ is the:
A. Liver
B. Skin
C. Thyroid
D. Lung
Correct Answer: A
A is correct because the liver stores several years' worth of vitamin B12 in many adults.
CSS - PMS - CCE - PCS - General Science
Vitamins
Neurologic deficits help distinguish vitamin B12 deficiency from uncomplicated folate deficiency because B12 deficiency can cause:
A. Subacute combined degeneration
B. Rickets
C. Scurvy
D. Xerophthalmia
Correct Answer: A
A is correct because B12 deficiency can damage the posterior and lateral spinal cord columns, causing paresthesia, ataxia and other neurologic signs.
CSS - PMS - CCE - PCS - General Science
Vitamins
Pernicious anemia results primarily from impaired absorption of:
A. Vitamin B12
B. Vitamin C
C. Vitamin D
D. Vitamin E
Correct Answer: A
A is correct because autoimmune loss of intrinsic factor or parietal cells prevents normal B12 absorption, causing pernicious anemia.
CSS - PMS - CCE - PCS - General Science
Vitamins
Intrinsic factor is secreted by:
A. Gastric parietal cells
B. Pancreatic beta cells
C. Hepatocytes
D. Colonocytes
Correct Answer: A
A is correct because parietal cells of the stomach secrete intrinsic factor as well as hydrochloric acid.
CSS - PMS - CCE - PCS - General Science
Vitamins
Absorption of vitamin B12 in the terminal ileum requires:
A. Intrinsic factor
B. Pepsin only
C. Bile pigment
D. Vitamin C transporter
Correct Answer: A
A is correct because B12 binds intrinsic factor in the small intestine and the complex is absorbed in the terminal ileum.
CSS - PMS - CCE - PCS - General Science
Vitamins
Natural dietary vitamin B12 is found mainly in:
A. Animal-derived foods
B. Refined vegetable oil only
C. Table sugar
D. Most unfortified fruits
Correct Answer: A
A is correct because natural B12 is concentrated in animal products; vegans generally require fortified foods or supplements.
CSS - PMS - CCE - PCS - General Science
Vitamins
Vitamin B12 contains which trace element at the center of its structure?
A. Cobalt
B. Iron
C. Copper
D. Zinc
Correct Answer: A
A is correct because cobalamin contains cobalt in its corrin ring.
CSS - PMS - CCE - PCS - General Science
Vitamins
Vitamin B12 is also called:
A. Cobalamin
B. Folate
C. Biotin
D. Niacin
Correct Answer: A
A is correct. Vitamin B12 is cobalamin, named for the cobalt atom in its structure.
CSS - PMS - CCE - PCS - General Science
Vitamins
Which metabolite is characteristically elevated in vitamin B12 deficiency but not isolated folate deficiency?
A. Methylmalonic acid
B. Uric acid
C. Lactic acid only
D. Pyruvate only
Correct Answer: A
A is correct because B12 is required for methylmalonyl-CoA mutase; methylmalonic acid rises in B12 deficiency but not in isolated folate deficiency.
CSS - PMS - CCE - PCS - General Science
Vitamins
Which laboratory marker is typically elevated in both folate and vitamin B12 deficiency?
A. Homocysteine
B. Calcium
C. Bilirubin only
D. Vitamin D
Correct Answer: A
A is correct because both folate and B12 deficiencies impair remethylation of homocysteine, causing elevated homocysteine.
CSS - PMS - CCE - PCS - General Science
Vitamins
Adequate folic acid around conception reduces the risk of:
A. Neural tube defects
B. Rickets
C. Scurvy
D. Night blindness
Correct Answer: A
A is correct because periconceptional folic acid substantially reduces neural tube defects such as spina bifida.
CSS - PMS - CCE - PCS - General Science
Vitamins
Folate deficiency most characteristically produces:
A. Megaloblastic anemia
B. Hemolytic anemia from G6PD deficiency
C. Microcytic iron-deficiency anemia only
D. Aplastic anemia
Correct Answer: A
A is correct because impaired DNA synthesis in folate deficiency causes megaloblastic, macrocytic anemia.
CSS - PMS - CCE - PCS - General Science
Vitamins
Folate is particularly important for synthesis of:
A. DNA nucleotides
B. Bile salts only
C. Thyroid hormones
D. Vitamin D in skin
Correct Answer: A
A is correct because folate coenzymes are required for purine synthesis and conversion of dUMP to dTMP, both essential for DNA synthesis.
CSS - PMS - CCE - PCS - General Science
Vitamins
The metabolically active folate coenzyme family is based on:
A. Tetrahydrofolate (THF)
B. Retinal
C. Calcitriol
D. Alpha-tocopherol
Correct Answer: A
A is correct because tetrahydrofolate derivatives transfer one-carbon units in nucleotide and amino-acid metabolism.
CSS - PMS - CCE - PCS - General Science
Vitamins
Which vitamin is designated B9?
A. Folate
B. Biotin
C. Cobalamin
D. Riboflavin
Correct Answer: A
A is correct. Vitamin B9 is folate; folic acid is the synthetic oxidized form used in supplements and fortification.