When we homogenise any tissue in an acid the acid soluble pool represents (a) Cytoplasm (b) Cell membrane (c)

NCERT Exemplar · Q7

Q. When we homogenise any tissue in an acid the acid soluble pool represents

(a) Cytoplasm

(b) Cell membrane

(d) Mitochondria

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Concept understanding — Acid Soluble Pool

Acid Soluble Pool

Imagine straining a bowl of soup through a fine sieve. The thin, watery broth runs through — that's your filtrate. The chunks of vegetable and meat stay behind in the sieve — that's your retentate. Biologists do something very similar to a piece of living tissue to find out what it's chemically made of, and the "broth" that runs through is called the acid-soluble pool.

How the pool is obtained

Take any living tissue — a slice of liver, a leaf, a potato — and grind it up with a mortar and pestle in a cold acid, typically trichloroacetic acid (Cl3CCOOH). Grinding in acid does two things at once: it breaks the cells open, and it instantly stops the chaos of enzymes still trying to react with everything (a technique sometimes called "acid quenching"). The result is a thick slurry. Strain that slurry through cheesecloth or cotton and it splits cleanly into two fractions:

Fraction	What it is	What's in it
Filtrate	The acid-soluble pool	Thousands of small organic molecules — amino acids, nucleosides, small sugars, free nitrogen bases, small peptides
Retentate	The acid-insoluble fraction	The macromolecules — proteins, nucleic acids, polysaccharides, plus resealed membrane fragments

Note

The name is precise on purpose. "Acid-soluble" doesn't mean "acidic in nature" — it means these are exactly the molecules that stay dissolved when the tissue is treated with acid, while the bigger molecules coagulate and drop out of solution.

Why it represents the cytoplasm

Inside a living cell, small molecules like amino acids, nucleotides and simple sugars aren't locked away inside organelles — they float freely, dissolved in the watery cytoplasm, ready to be picked up whenever the cell needs to build something bigger or run a reaction. When you homogenise the tissue, this is exactly the population of molecules that ends up passing through the sieve as filtrate. That's why the acid-soluble pool is taken to roughly represent the chemical make-up of the cytoplasm — not the nucleus, not the mitochondria, and not the cell membrane, all of which are themselves built largely from insoluble macromolecules and membrane material that get trapped in the retentate instead.

Important

A very common mix-up is to think the acid-soluble pool represents "the whole cell." It doesn't — it only captures the freely dissolved small-molecule fraction. The insoluble fraction (proteins, nucleic acids, polysaccharides, membrane vesicles) is just as much a part of the cell, and together the two fractions make up the entire chemical composition of the tissue.

What's inside the pool

When chemists have actually gone looking inside the acid-soluble pool, they've catalogued thousands of distinct organic compounds — far more variety than the handful of macromolecule types found in the insoluble fraction. Broadly, four families dominate it: …

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The acid-soluble pool obtained by grinding tissue in acid stands in for the cytoplasm's composition, since the macromolecules of organelles and structural machinery are left behind in the acid-insoluble fraction - option (A).

When a living tissue is ground with an acid such as trichloroacetic acid and the resulting slurry is strained, it splits cleanly into two parts. The filtrate, or acid-soluble pool, holds the thousands of small organic compounds that were freely dissolved throughout the cell - amino acids, nucleosides, small sugars and similar molecules. The retentate, or acid-insoluble fraction, holds the large macromolecules: proteins, nucleic acids, polysaccharides, along with lipid-containing membrane fragments that reseal into insoluble vesicles.

Because the small, freely dissolved molecules are exactly what fills the general cytoplasmic composition of the cell, the acid-soluble pool is taken to roughly represent the composition of the cytoplasm. The acid-insoluble fraction, by contrast, represents the macromolecules of the cytoplasm and organelles together. …

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Q.When we homogenise any tissue in an acid the acid soluble pool represents

Concept understanding — Acid Soluble Pool

Acid Soluble Pool

How the pool is obtained

Why it represents the cytoplasm

What's inside the pool

Method: Recalling what the acid-precipitation experiment separates

Q.When we homogenise any tissue in an acid the acid soluble pool represents

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