Microorganisms can be effectively removed from a liquid without heating by which process? (Select the method that physically separates cells from fluids.)

Introduction:
Some heat-sensitive solutions (e.g., vitamins, antibiotics, sera) cannot be sterilized by autoclaving. This question asks for the non-thermal method that removes microbes while preserving solute integrity.

Given Data / Assumptions:

• We aim to remove, not necessarily kill, microorganisms.
• Membrane filters with pore sizes 0.2–0.45 μm can retain bacteria.
• Viruses require smaller pore sizes or specialized filters.

Concept / Approach:
Filtration passes liquid through a membrane; particles larger than the pore size are retained. Sterile filtrates are collected downstream under aseptic conditions.

Step-by-Step Solution:
Identify constraint: heat sensitivity of the solution. Select a physical separation method rather than a killing method. Recognize membrane filtration as standard for sterile preparation of lab solutions. Choose “filtration.”

Verification / Alternative check:
Pharmacopeias describe sterile filtration for parenteral solutions that cannot be autoclaved.

Why Other Options Are Wrong:

• Freeze-drying / Desiccation: Dehydrates but does not reliably remove or kill microbes.
• Osmosis: Refers to solvent movement; not a sterilization/removal process.

Common Pitfalls:
Assuming dehydration equals sterilization; survivors can persist and recover upon rehydration.

Final Answer:
filtration removes microbes from liquids without heat.