What is the function of the plasma membrane?

• A. To increase the temperature of the cell
• B. To protect the cell and regulate substance passage
• C. To produce energy for the cell
• D. To store genetic information

Answer: (B)

The plasma membrane serves a critical role in cellular function by acting as a barrier that protects the cell from the external environment while also regulating the passage of substances in and out of the cell. This selective permeability is essential for maintaining homeostasis, as it allows the cell to control its internal conditions, such as ion concentrations and nutrient levels, while simultaneously keeping out harmful substances. The plasma membrane is composed of a lipid bilayer that contains various proteins and other molecules which facilitate this transport and communication with the environment.

Other choices do not accurately represent the role of the plasma membrane. Increasing the temperature of the cell is not a function attributed to the membrane, nor is energy production; these processes are primarily associated with organelles like mitochondria. Storing genetic information is a function of the cell nucleus rather than the plasma membrane. Thus, the correct answer emphasizes the protective and regulatory functions of the plasma membrane, highlighting its importance in cellular integrity and function.