Question

The osmotically fragile protoplasts look completely spherical under microscope in which of the following solution?

• A. Hypotonic
• B. Hypertonic
• C. Slightly hypotonic
• D. Slightly hypertonic

Hint:

Protoplasts need a "hug" from the solution. Slightly Hypertonic provides that gentle pressure to keep them perfectly Round.

Answer 1

The Correct Option is D

Concept: Protoplasts are plant cells without cell walls. Because they lack the rigid outer support of the wall, they are extremely sensitive to osmotic pressure. They act like tiny balloons that can burst or shrivel based on the surrounding liquid.

Step 1: Analyzing Osmotic States.

• Hypotonic (1): Water enters the cell. Without a wall to stop it, the protoplast will swell and eventually burst (lyse).
• Hypertonic (2): Water leaves the cell. The protoplast will shrivel and become irregularly shaped (plasmolysis).

Step 2: Identifying the Optimal State.
To maintain a healthy, completely spherical shape, protoplasts require a medium that is slightly hypertonic (4) to their own cytoplasm. This provides enough external pressure to keep the plasma membrane taut and smooth in a perfect circle without being so strong that it causes shriveling.

Step 3: Conclusion.
In laboratory isolation, stabilizers like mannitol or sorbitol are used to create this slightly hypertonic environment to ensure the protoplasts remain intact and perfectly round for viewing and further use.