Process that draws the solvent from a less concentrated solute through a selectively permeable membrane into a more concentrated solute till the point of equalization is called?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2016

Explanation

The question describes the movement of a solvent (like water) across a selectively permeable membrane.
The movement is from a region of lower solute concentration to a region of higher solute concentration.
This process aims to equalize the solute concentrations on both sides of the membrane.
This specific set of characteristics is the textbook definition of osmosis.

Option B: Diffusion describes the movement of solute particles, not the solvent. The movement is also in the opposite direction relative to the concentration gradient (from high to low).
Option C: Ultra-filtration is a high-pressure filtration process. The driving force is hydrostatic pressure, not a concentration gradient (osmotic pressure).
Option D: Filtration is driven by hydrostatic pressure, which pushes fluid and solutes across a membrane. The question describes a process driven by solute concentration differences.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Principles of fluid and solute transport across membranes as background academic context rather than a clinical decision trigger.
Understanding osmosis is critical for administering IV fluids. Isotonic solutions (0.9% NaCl) have the same osmolality as blood and don't cause significant fluid shifts. Hypotonic solutions (0.45% NaCl) cause fluid to move into cells, while hypertonic solutions (3% NaCl) pull fluid out of cells.
Osmosis is fundamental to maintaining cellular hydration and volume. Imbalances can lead to cells shrinking (crenation) in hypertonic environments or swelling and bursting (lysis) in hypotonic environments.
The concept of colloid osmotic (oncotic) pressure, where proteins like albumin pull water back into capillaries via osmosis, is key to understanding fluid balance. Low albumin levels can lead to edema as fluid is not effectively returned to circulation.

How to Approach the Question

First, break down the question into its core components. Identify what is moving, what it is moving through, and the direction of movement.
The question states the 'solvent' is moving. This is a key differentiator.
The movement is through a 'selectively permeable membrane'.
The direction is from a 'less concentrated solute' area to a 'more concentrated solute' area.
Evaluate each option against these components. Osmosis is the only process where the solvent moves from a low solute concentration to a high solute concentration across a semipermeable membrane.
Eliminate options based on their driving force. Diffusion is driven by a concentration gradient of the solute, while filtration is driven by hydrostatic pressure.

Concept Tested & Keywords

Concept Tested: Principles of fluid and solute transport across membranes
Stem keywords: solvent, less concentrated, selectively permeable membrane, more concentrated, equalization
Lead-in keywords: is called

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