Question

Contraction of the protoplast of a plant cell as a result of loss of water from the cell is :

• A. Endocytosis
• B. Plasmolysis
• C. Exocytosis
• D. Lysis

Hint:

Plasmolysis is a unique phenomenon observed in plant cells due to their rigid cell wall. When a plant cell loses water in a hypertonic environment, its protoplast shrinks and pulls away from the cell wall, but the cell wall itself retains its shape.

Answer 1

The Correct Option is B

Step 1: Understand the process of water movement in cells.
Water moves across cell membranes by osmosis, from an area of higher water concentration (lower solute concentration) to an area of lower water concentration (higher solute concentration). Step 2: Define the terms related to cell volume changes.

Plasmolysis: This is the process where the protoplast (the living part of the plant cell, including the cell membrane, cytoplasm, and nucleus) shrinks and pulls away from the cell wall when the cell loses water due to being placed in a hypertonic solution (a solution with a higher solute concentration than the cell's cytoplasm).
Endocytosis: This is the process by which cells take in substances from outside by engulfing them in a vesicle formed from the cell membrane. It involves the inward budding of the cell membrane.
Exocytosis: This is the process by which cells release substances outside the cell by fusing a vesicle containing the substance with the cell membrane. It involves the outward budding of the cell membrane.
Lysis: This refers to the bursting or disintegration of a cell, typically due to excessive water intake (in hypotonic solutions for animal cells) or damage to the cell membrane. Plant cells are usually protected from lysis by their rigid cell wall in hypotonic solutions. Step 3: Relate the given description to the definitions.
The question describes "Contraction of the protoplast of a plant cell as a result of loss of water from the cell". This precisely matches the definition of plasmolysis. Step 4: Conclude the correct term.
The phenomenon described is plasmolysis. (2) Plasmolysis