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.
CSS - PMS - CCE - PCS - General Science
Vitamins
Raw egg whites consumed in very large amounts can contribute to biotin deficiency because they contain:
A. Avidin
B. Intrinsic factor
C. Trypsin
D. Calcitonin
Correct Answer: A
A is correct because avidin binds biotin strongly and reduces its intestinal absorption; cooking denatures avidin.
CSS - PMS - CCE - PCS - General Science
Vitamins
Biotin acts mainly as a cofactor for enzymes that perform:
A. Carboxylation reactions
B. Gamma-carboxylation of clotting factors
C. DNA methylation only
D. Phototransduction
Correct Answer: A
A is correct because biotin is covalently attached to carboxylases involved in fatty-acid synthesis, gluconeogenesis and amino-acid metabolism.
CSS - PMS - CCE - PCS - General Science
Vitamins
Vitamin B7 is better known as:
A. Biotin
B. Niacin
C. Folate
D. Thiamine
Correct Answer: A
A is correct. Vitamin B7 is biotin.
CSS - PMS - CCE - PCS - General Science
Vitamins
Excessive long-term vitamin B6 supplementation can itself cause:
A. Sensory neuropathy
B. Rickets
C. Pellagra
D. Bleeding from vitamin K deficiency
Correct Answer: A
A is correct because chronic high-dose pyridoxine can damage sensory nerves and produce neuropathy.
CSS - PMS - CCE - PCS - General Science
Vitamins
Severe vitamin B6 deficiency may cause:
A. Peripheral neuropathy and microcytic/sideroblastic anemia
B. Scurvy
C. Osteomalacia only
D. Xerophthalmia
Correct Answer: A
A is correct because B6 deficiency can impair heme synthesis and neurotransmitter metabolism, causing neuropathy, dermatitis and sideroblastic anemia.
CSS - PMS - CCE - PCS - General Science
Vitamins
Which drug is well known to increase the risk of vitamin B6 deficiency and is often given with pyridoxine?
A. Isoniazid
B. Paracetamol
C. Amoxicillin
D. Metformin only
Correct Answer: A
A is correct because isoniazid can cause functional pyridoxine deficiency and peripheral neuropathy; pyridoxine is often co-prescribed in at-risk patients.