Vitamins & Minerals — Set 5

Correct Answer: A. Zinc

• **Zinc** = Zinc is a cofactor for over 300 enzymes involved in protein synthesis, cell division, and DNA repair — all critical processes for wound healing; it also regulates the maturation and activation of T-lymphocytes and natural killer cells in the immune system. • **Metallothionein regulation** — zinc modulates the inflammatory response by controlling the release of cytokines and is required for the activity of thymulin, a thymus hormone that promotes T-cell differentiation. • Oysters are the richest dietary source of zinc; it is also found in red meat, seeds, and legumes. • 💡 Option B (Potassium) is wrong because potassium regulates heart rhythm and fluid balance, not wound healing or immune cell development; Option C (Chlorine) is wrong because chlorine, as chloride, mainly maintains electrolyte balance and stomach acid production; Option D (Sodium) is wrong because sodium controls fluid balance and nerve impulse transmission, not immune function.

Correct Answer: C. Vitamin C

• **Vitamin C** = Vitamin C (Ascorbic Acid) is required for the synthesis of collagen, the structural protein that holds gum tissue together and anchors teeth in their sockets; deficiency weakens collagen fibres, causing gums to bleed and teeth to loosen — the hallmark of Scurvy. • **Hydroxylation role** — Vitamin C is the cofactor for prolyl hydroxylase and lysyl hydroxylase enzymes that add hydroxyl groups to collagen's proline and lysine residues, cross-linking the fibres for mechanical strength. • Scurvy was historically common among sailors on long voyages who lacked access to fresh fruits and vegetables. • 💡 Option A (Vitamin D) is wrong because Vitamin D deficiency weakens bones (Rickets/Osteomalacia) rather than causing gum bleeding; Option B (Vitamin A) is wrong because Vitamin A deficiency primarily causes night blindness and dry eyes (Xerophthalmia); Option D (Vitamin B) is wrong because Vitamin B deficiencies cause neurological disorders and anaemia, not gum bleeding.

Correct Answer: B. Osteomalacia

• **Osteomalacia** = In adults, Vitamin D deficiency causes Osteomalacia (soft bones), where insufficient calcium is deposited in the bone matrix, making bones painful, soft, and prone to fractures — unlike Rickets, which affects the growth plates of children. • **Distinction from Rickets** — Rickets occurs in children whose bones are still growing, causing bowed legs and stunted growth; Osteomalacia is the adult equivalent where already-formed bone loses its mineral content without affecting growth plates. • Osteomalacia is treated with Vitamin D and calcium supplementation along with increased sunlight exposure. • 💡 Option A (Beriberi) is wrong because Beriberi results from Vitamin B1 (Thiamine) deficiency and affects the nervous and cardiovascular systems; Option C (Night blindness) is wrong because Night blindness is caused by Vitamin A deficiency impairing rhodopsin production; Option D (Scurvy) is wrong because Scurvy is caused by Vitamin C deficiency affecting collagen synthesis.

Correct Answer: B. Calcium

• **Calcium** = During muscle contraction, calcium ions released from the sarcoplasmic reticulum bind to troponin on the actin filament, causing a conformational change that exposes myosin-binding sites and triggers the contraction cycle — this applies equally to skeletal, smooth, and cardiac muscle. • **Cardiac pacemaker role** — in the heart's sinoatrial node, calcium influx through slow channels is responsible for the slow depolarisation phase of the pacemaker potential, determining the heart's natural rhythm. • Very low blood calcium (hypocalcaemia) causes muscle cramps and, in severe cases, tetany (sustained involuntary muscle contraction). • 💡 Option A (Iodine) is wrong because iodine is needed for thyroid hormone synthesis, not muscle contraction; Option C (Fluorine) is wrong because fluorine (as fluoride) hardens tooth enamel and is not involved in muscle physiology; Option D (Iron) is wrong because iron carries oxygen in haemoglobin but does not directly trigger muscle contraction.

Correct Answer: A. Vitamin K

• **Vitamin K** = Phylloquinone is the IUPAC chemical name for Vitamin K1, the plant-synthesised form; "phyllo" refers to its origin in plant leaves (Greek: phyllon = leaf) and "quinone" describes its naphthoquinone ring structure. • **Two natural forms** — Vitamin K1 (Phylloquinone) is from green plants; Vitamin K2 (Menaquinone) is produced by gut bacteria and found in fermented foods like natto; both support blood clotting and bone metabolism. • Vitamin K is fat-soluble and is stored mainly in the liver. • 💡 Option B (Vitamin D) is wrong because Vitamin D1 form is Calciferol, not Phylloquinone; Option C (Vitamin E) is wrong because Vitamin E is chemically known as Tocopherol; Option D (Vitamin A) is wrong because Vitamin A is chemically known as Retinol.

Correct Answer: B. Vitamin A

• **Vitamin A** = Xerophthalmia (from Greek: dry eye) is a progressive eye disorder caused by Vitamin A deficiency; it begins with night blindness, advances to dryness and ulceration of the cornea (Keratomalacia), and can lead to permanent blindness if untreated. • **Rhodopsin connection** — Vitamin A (as 11-cis-retinal) is the light-sensitive component of rhodopsin in rod cells; without it, the eye cannot generate signals in dim light, causing night blindness as the earliest symptom. • Xerophthalmia is the leading cause of preventable childhood blindness worldwide, particularly in South and Southeast Asia. • 💡 Option A (Vitamin B) is wrong because Vitamin B deficiencies cause neurological problems, anaemia, and mouth sores, not dry eyes; Option C (Vitamin C) is wrong because Vitamin C deficiency causes Scurvy with gum bleeding, not eye dryness; Option D (Vitamin D) is wrong because Vitamin D deficiency affects bone mineralisation, not corneal health.

Correct Answer: B. Iodine

• **Iodine** = The neck swelling referred to is Goitre, an enlargement of the thyroid gland caused by iodine deficiency; governments mandate iodisation of table salt (adding potassium iodate or potassium iodide) as a cost-effective public health measure to prevent this. • **Feedback mechanism** — when iodine is scarce, the pituitary gland secretes excess Thyroid Stimulating Hormone (TSH) to stimulate the thyroid, causing it to enlarge as it tries to capture more iodine from the blood, forming a goitre. • India introduced the universal iodisation of edible salt as a national programme; this measure has significantly reduced goitre prevalence. • 💡 Option A (Zinc) is wrong because zinc deficiency causes growth retardation and immune weakness, not goitre; Option C (Copper) is wrong because copper deficiency leads to anaemia and connective tissue problems, not thyroid enlargement; Option D (Magnesium) is wrong because magnesium deficiency causes muscle cramps and arrhythmias, not neck swelling.

Correct Answer: A. Folic Acid (Vitamin B9)

• **Folic Acid (Vitamin B9)** = Folic Acid is required for the synthesis of DNA nucleotides and rapid cell division; during the first 28 days of pregnancy — often before a woman knows she is pregnant — sufficient folate is critical to close the neural tube, which forms the brain and spinal cord. • **Mechanism of protection** — Folic Acid donates methyl groups in one-carbon metabolism, enabling the synthesis of purines and thymidylate needed for DNA replication in rapidly dividing neural progenitor cells; deficiency leads to Spina Bifida or Anencephaly. • WHO and health ministries recommend periconceptional folic acid supplementation (400 µg/day) for all women of childbearing age. • 💡 Option B (Vitamin E) is wrong because Vitamin E is an antioxidant that protects cell membranes, not a specific regulator of neural tube closure; Option C (Vitamin C) is wrong because Vitamin C builds collagen and boosts immunity but does not govern neural tube formation; Option D (Vitamin B1) is wrong because Thiamine supports carbohydrate metabolism and nerve function but is not specifically linked to neural tube defects.

Correct Answer: D. Magnesium

• **Magnesium** = Chlorophyll is a porphyrin-based pigment with a magnesium ion at the centre of its tetrapyrrole ring; this magnesium is essential for absorbing red and blue wavelengths of light and transferring the captured energy to the photosynthesis reaction centre. • **Structural parallel to haemoglobin** — Chlorophyll's magnesium-centred porphyrin ring is structurally analogous to the iron-centred haem group in haemoglobin; in plants it captures light energy, while in animals haem captures and carries oxygen. • Magnesium deficiency in plants causes chlorosis (yellowing of leaves) as chlorophyll breaks down. • 💡 Option A (Zinc) is wrong because zinc is a cofactor for carbonic anhydrase and other plant enzymes, but is not part of the chlorophyll molecule; Option B (Iron) is wrong because iron is the central atom of the haem group in haemoglobin and plant cytochromes, not in chlorophyll; Option C (Manganese) is wrong because manganese is involved in the oxygen-evolving complex of photosystem II, but is not the central atom of chlorophyll.

Correct Answer: D. Cyanocobalamin

• **Cyanocobalamin** = Cyanocobalamin is the synthetic, stable form of Vitamin B12 used in supplements; the name combines "cyano" (a cyanide ligand attached to the central cobalt atom in the lab-produced form) and "cobalamin" (from cobalt, the central metal). • **Active coenzyme forms** — in the body, Cyanocobalamin is converted to the two active coenzyme forms: Methylcobalamin (needed for methionine synthesis and homocysteine metabolism) and Adenosylcobalamin (needed for fatty acid metabolism via methylmalonyl-CoA mutase). • Vitamin B12 is found exclusively in animal products; vegans must supplement to avoid deficiency, which causes megaloblastic anaemia and subacute combined degeneration of the spinal cord. • 💡 Option A (Niacin) is wrong because Niacin is the chemical name for Vitamin B3; Option B (Pyridoxine) is wrong because Pyridoxine is the chemical name for Vitamin B6; Option C (Riboflavin) is wrong because Riboflavin is the chemical name for Vitamin B2.