Seaweeds are important source of -

Question

UnlockIAS · Accepted Answer

Correct — B, Iodine. Seaweeds (marine macroalgae, especially brown seaweeds/kelps such as Laminaria) take up and concentrate iodine from seawater to levels many thousands of times higher than the surrounding water, storing it in their tissues. Historically, burnt dried seaweed ('kelp ash') was the world's principal commercial source of iodine in the 19th century, and seaweed remains one of the richest natural dietary sources of the element — which is why iodine deficiency is rare in seaweed-eating coastal populations.

Why the other options are wrong — (a) Argon is an inert noble gas obtained by the fractional distillation of liquefied air. It is not produced by any living organism, so seaweed plays no part in its supply — this is the obvious throw-away option.  (c) Chlorine is obtained industrially by the electrolysis of brine (common-salt solution), i.e. from the dissolved sodium chloride in seawater, not from seaweed tissue. Seaweed is not a commercial source of chlorine.  (d) Bromine is extracted from seawater and salt-lake brines (bromide ions) and from the Dead Sea — again from the water/brine, not from seaweed. The signature element that seaweed selectively accumulates and was historically harvested for is iodine, not bromine.

Concept: Seaweeds are photosynthetic marine algae, grouped as green, brown and red. Brown seaweeds/kelps are notable bio-accumulators of iodine, absorbing iodide from seawater and concentrating it in their tissue. Besides iodine, seaweeds are the source of important hydrocolloids: agar and carrageenan from red algae, and algin/alginate from brown algae, all widely used in food and pharmaceuticals.

State PCS 2023 Q27 — Science & Technology PYQ with Answer

State PCS 2023 Q27 — Science & Technology PYQ with Answer