What is a primary function of the cell membrane?

The primary function of the cell membrane is to control the intake and output of substances, which is fundamental to maintaining the internal environment of the cell. The cell membrane acts as a selective barrier, allowing certain molecules to enter or exit the cell while preventing others from passing through. This selective permeability is crucial for various cellular processes, including nutrient intake, waste removal, and the maintenance of ion concentrations necessary for cellular functions.

The phospholipid bilayer of the cell membrane, along with embedded proteins, plays a key role in its ability to transport substances. For example, transport proteins facilitate the movement of specific ions and molecules across the membrane, contributing to the overall homeostasis of the cell.

In contrast, the other choices do not accurately reflect the main role of the cell membrane in a way that encompasses its essential functions. The generation of energy occurs primarily in organelles like mitochondria, cell division is facilitated by a combination of mechanisms involving numerous cellular structures, and production of cellular components typically takes place within the cytoplasm or specific organelles rather than being a direct function of the membrane itself.