Organic Acid

11. Stinging hair of nettle leaves inject fluid in the human body causing

Stinging hair of nettle leaves inject fluid in the human body causing burning pain. The fluid is

[amp_mcq option1=”Methanoic acid” option2=”Tartaric acid” option3=”Hydrochloric acid” option4=”Sulphuric acid” correct=”option1″]

This question was previously asked in
UPSC CDS-2 – 2022
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The stinging sensation and burning pain caused by contact with nettle leaves (like *Urtica dioica*) are due to fine, brittle hairs (trichomes) on the plant surface that break off and inject chemicals into the skin. The fluid injected contains several irritants, including histamine, acetylcholine, serotonin, and notably, formic acid, which is also known as methanoic acid. Methanoic acid is a simple carboxylic acid that contributes significantly to the burning and stinging sensation.
Nettle stings inject chemicals including methanoic acid (formic acid).
Other acids like tartaric acid are found in fruits like grapes and tamarind. Hydrochloric acid and Sulphuric acid are strong mineral acids not typically found in biological tissues in this manner.

12. Methanoic acid is normally found in :

Methanoic acid is normally found in :

[amp_mcq option1=”muscles” option2=”urine” option3=”ant stings” option4=”human brain” correct=”option3″]

This question was previously asked in
UPSC CDS-1 – 2022
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Methanoic acid (formic acid, HCOOH) is notably found in the venom of ants and in the stinging hairs of nettles. It is injected when an ant bites or when contact is made with a nettle, causing pain and irritation.
Methanoic acid is the simplest carboxylic acid. Its historical name, formic acid, comes from the Latin word “formica,” meaning ant, due to its initial isolation from ants.
Lactic acid is found in muscles (formed during anaerobic respiration). Urine contains urea and other waste products. The human brain contains various complex organic molecules, including neurotransmitters and lipids, but methanoic acid is not a primary constituent.
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