Analyzing Plant Cell Concepts: Correctly Matched Pairs

This question asks us to identify the correctly matched pair among the given options related to plant cell biology. Let's analyze each option to understand the concepts involved.

Option 1: Plasmolysis - Gain of water by plant cell

This statement is incorrect. Plasmolysis is the process where the protoplasm of a plant cell shrinks away from its cell wall due to water loss by osmosis. This typically happens when the cell is placed in a hypertonic solution. The opposite process, the gain of water by a plant cell, leads to turgidity and is sometimes referred to as deplasmolysis when it occurs after plasmolysis.

Option 2: Cell wall - Composed mainly of protein

This statement is incorrect. The primary structural component of the cell wall in plant cells is cellulose, a complex carbohydrate. While some proteins are present in the cell wall (like enzymes or structural proteins), they are not the main component. The bulk of the cell wall's structure comes from cellulose.

Option 3: Cellulose - Provides structural strength to plant cells

This statement is correctly matched. Cellulose is a long chain of glucose molecules that forms microfibrils. These microfibrils are arranged in layers within the plant cell wall, providing significant tensile strength and rigidity. This structural support is crucial for maintaining the shape of the plant cell and preventing it from bursting due to osmotic pressure.

Option 4: Plasma membrane - Located outside the cell wall

This statement is incorrect. The plasma membrane (also called the cell membrane) is located just inside the cell wall. It surrounds the cytoplasm and regulates the passage of substances into and out of the cell. The cell wall is the outermost layer of a plant cell, providing external protection and support.

Conclusion

Based on the analysis of each option:

• Plasmolysis involves water loss, not gain.
• Plant cell walls are primarily made of cellulose, not protein.
• Cellulose is indeed key for the structural strength of plant cells.
• The plasma membrane is inside, not outside, the cell wall.

Therefore, the only correctly matched pair describes the role of cellulose.