Question

Sequentially arrange the steps involved in cryopreservation of plant cells in order of their occurrence.
A. Raising sterile tissue culture
B. Determination of viability
C. Freezing, Storage
D. Addition of cryoprotectants.
Choose the correct answer from the options given below:

• A. A, D, C, B
• B. A, B, C, D
• C. B, A, D, C
• D. C, B, D, A

Hint:

Think of cryopreservation like preparing a valuable item for long-term storage. First, you get the item (A. raise culture). Then, you wrap it in protective material (D. add cryoprotectants). Next, you put it in the storage unit (C. freeze). Finally, when you take it out, you check if it's still in good condition (B. determine viability).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question asks for the correct chronological order of the major steps involved in cryopreservation, which is the process of preserving biological material (like plant cells) by cooling it to very low temperatures, typically in liquid nitrogen (\(-196^\circ\)C).
Step 2: Detailed Explanation:
Let's analyze the logical flow of the process:

A. Raising sterile tissue culture: First, you need the biological material to preserve. You start by growing a healthy, sterile, and actively dividing culture of the plant cells or tissues. This is the starting material.
D. Addition of cryoprotectants: Before freezing, you must treat the cells with cryoprotectants (e.g., DMSO, glycerol). These substances protect the cells from damage caused by ice crystal formation during the freezing process. This is a crucial pre-treatment step.
C. Freezing, Storage: After adding cryoprotectants, the cells are subjected to a controlled cooling protocol to freeze them, and then they are transferred to long-term storage in liquid nitrogen.
B. Determination of viability: After a period of storage, and especially when you need to use the material, the cells are thawed. It is then essential to test their viability (i.e., to check if they have survived the freezing and thawing process) using methods like staining (e.g., with TTC or fluorescein diacetate). This is the final quality-control step.
Step 3: Final Answer:
The correct sequence of steps is: Raise the culture (A), add protective chemicals (D), freeze and store it (C), and finally, check if it survived (B). This corresponds to the order A, D, C, B.