What characteristic of the plasma membrane is crucial for cell homeostasis?

• A. Its rigidity and strength
• B. Its permeability to all substances
• C. Its selective permeability
• D. Its ability to conduct electricity

Answer: (C)

The characteristic of the plasma membrane that is crucial for cell homeostasis is its selective permeability. This means that the plasma membrane is able to control which substances can enter and exit the cell, allowing for the maintenance of an optimal internal environment that is different from the external one. This selective nature enables the cell to regulate essential processes such as nutrient uptake, waste removal, and ion balance, all of which are vital for maintaining homeostasis.

For example, glucose and certain ions can be transported into the cell while waste products can be exported out, without allowing harmful substances to enter. This selective permeability is primarily due to the structure of the lipid bilayer and the presence of various transport proteins that facilitate specific movements of molecules across the membrane.

In contrast, options that describe the rigidity and strength of the membrane do not directly address homeostasis, as flexibility can also be important for cell function. The notion of permeability to all substances contradicts the fundamental operation of biological membranes, which is to selectively allow certain molecules through. Lastly, while the ability to conduct electricity is relevant for certain types of cells (like neurons), it is not a defining feature for maintaining homeostasis in all cell types. Thus, the selective permeability of the plasma membrane is what fundamentally supports the ability of