What is the primary role of the cell membrane?

The primary role of the cell membrane is to control what enters and exits the cell. This semi-permeable barrier is essential for maintaining homeostasis within the cell by regulating the movement of substances such as ions, nutrients, and waste products. The cell membrane consists of a phospholipid bilayer with embedded proteins that facilitate selective transport processes, allowing the cell to respond to changes in its environment. This regulation is critical for the cell's survival and function, as it ensures that essential molecules are taken in while harmful substances are kept out.

While other processes, such as energy production, genetic information storage, and protein synthesis, are vital to cellular function, they are not the primary responsibility of the cell membrane.