Which technique is used for separating colloidal particles from small ions using a cellophane and collodion?

RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Biochemistry and Nutrition

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

Dialysis is the specific technique for separating large colloidal particles from small ions (crystalloids) based on their differential rates of diffusion through a semipermeable membrane.
The principle relies on particle size; the pores of the membrane (like cellophane) are small enough to block large colloids while allowing small ions and solvent molecules to pass through.
This process effectively purifies the colloidal solution by removing unwanted small solutes.
The question's description of separating colloids from ions using a cellophane membrane is the exact definition of dialysis.

Option A: Diffusion is the underlying physical principle of particle movement from high to low concentration. It is the mechanism by which small ions move across the membrane during dialysis, but it is not the name of the overall separation technique.
Option C: Osmosis specifically refers to the movement of a solvent (usually water) across a semipermeable membrane, not the separation of solute particles based on size.
Option D: Viscosity is a measure of a fluid's resistance to flow or its 'thickness'. It is a physical property of a substance, not a technique for separating particles.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Separation of colloids and crystalloids using a semipermeable membrane as background academic context rather than a clinical decision trigger.
Understanding dialysis is crucial for nurses, especially in nephrology, as it is the principle behind hemodialysis and peritoneal dialysis for patients with kidney failure.
Nurses monitor patients undergoing dialysis for complications such as hypotension, muscle cramps, and disequilibrium syndrome, all of which relate to the rapid shifts in fluid and electrolytes.
What if the patient's blood pressure drops significantly during hemodialysis? The nurse's first action is often to decrease the rate of fluid removal (ultrafiltration) and may administer a bolus of normal saline to restore intravascular volume, demonstrating a direct application of managing fluid shifts related to this process.

How to Approach the Question

First, identify the key terms in the question: 'separating', 'colloidal particles', 'small ions', and 'cellophane/collodion' (a semipermeable membrane).
Recognize that the question is asking for a specific separation technique based on particle size using a membrane.
Evaluate each option based on its scientific definition.
Eliminate 'Viscosity' as it's a fluid property, not a separation method.
Differentiate between 'Dialysis' and 'Osmosis'. Osmosis is the movement of the solvent (water), while the question is about separating solutes (particles). This eliminates Osmosis.
Differentiate between 'Dialysis' and 'Diffusion'. Diffusion is the general movement of particles, while Dialysis is the specific name for the technique that uses a membrane to separate particles by size. Therefore, Dialysis is the most precise and correct answer.

Concept Tested & Keywords

Concept Tested: Separation of colloids and crystalloids using a semipermeable membrane.
Stem keywords: separating, colloidal particles, small ions, cellophane, collodion
Lead-in keywords: Which technique

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 24-26