The method in which the cells are frozen and dehydrated is called

Appeared in: UPUMS Nsg.Officer-2024

Explanation

Lyophilization is the scientific term for the process commonly known as freeze-drying.
It is a two-step process: first, the material is completely frozen, typically at very low temperatures.
Second, a deep vacuum is applied, and a small amount of heat is introduced, causing the frozen water to turn directly into vapor (sublimation) without passing through a liquid phase.
This method is superior for preserving the structure of delicate biological materials like proteins, cells, and viruses because it avoids the damage that can be caused by ice crystals in slower freezing or simple dehydration.

Option A: Pasteurization uses heat to kill microorganisms, which is the opposite of the freezing process described in the question.
Option B: Dessication involves only dehydration (drying) and does not include the initial freezing step. The question specifically mentions both freezing and dehydration.
Option D: Disinfection is the process of eliminating pathogenic microorganisms from inanimate objects or surfaces. It does not involve preserving cells; its purpose is to destroy them.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Methods of sterilization and preservation as background academic context rather than a clinical decision trigger.
Lyophilization is essential for extending the shelf life of many modern medicines, especially biologic drugs and vaccines (e.g., MMR, varicella, and some COVID-19 vaccines), allowing them to be stored and transported without refrigeration.
In laboratories, it is used to preserve microbial cultures, enzymes, and other biological samples for long-term storage and research.
What if? If a vaccine was heat-sensitive but did not require long-term storage in a powdered form, it might be preserved by simple refrigeration (cooling) rather than lyophilization.

How to Approach the Question

This is a factual recall question that tests your knowledge of scientific terminology.
First, identify the two key processes described in the question stem: 'frozen' and 'dehydrated'.
Next, evaluate each option to see which one incorporates both of these processes.
Eliminate 'Pasteurization' as it involves heating, not freezing.
Eliminate 'Dessication' because, while it means dehydration, it does not involve freezing.
Eliminate 'Disinfection' as its purpose is to kill microbes, not preserve cells.

Concept Tested & Keywords

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E6 Nutrition Monika Sharma 3e pp. 284-286, 285-287

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