What is the primary role of the cell membrane?

The primary role of the cell membrane is to protect the cell's contents. It serves as a barrier that separates the interior of the cell from the external environment. This membrane is selectively permeable, meaning it allows certain substances to enter or exit the cell while keeping others out. This regulation is crucial for maintaining homeostasis within the cell, allowing it to maintain an appropriate internal environment despite changes outside. The integrity of the cell membrane is vital for protecting cellular components from damage and helps in the communication with other cells through receptors embedded in the membrane.

While controlling cell growth, facilitating energy production, and storing genetic material are important functions in the cell, they do not directly pertain to the cell membrane's primary role, which is fundamentally about protecting the cell.