Which of the following is a defining feature of biological membranes?

• A. Selective permeability
• B. Uniform composition
• C. High electrical conductivity
• D. Rigid structure

Answer: (A)

Verified step by step guidance

1. Begin by understanding the concept of biological membranes. Biological membranes are structures that separate the interior of cells from the external environment and also compartmentalize the interior of cells.
2. Consider the options given: Selective permeability, Uniform composition, High electrical conductivity, and Rigid structure. Reflect on the characteristics of biological membranes.
3. Selective permeability is a key feature of biological membranes. This means that the membrane allows certain molecules or ions to pass through it while blocking others, which is crucial for maintaining homeostasis within the cell.
4. Evaluate the other options: Uniform composition is not a defining feature because biological membranes are composed of various lipids, proteins, and carbohydrates, which can vary in composition. High electrical conductivity is not typical of biological membranes, as they generally act as insulators. Rigid structure is incorrect because biological membranes are fluid and flexible, allowing for movement and changes in shape.
5. Conclude that selective permeability is the defining feature of biological membranes, as it is essential for controlling the movement of substances in and out of the cell, thereby maintaining the cell's internal environment.