What is the function of the cell membrane?

The function of the cell membrane is to regulate the transport of materials in and out of the cell. This selective permeability is vital for maintaining homeostasis within the cell, allowing essential nutrients to enter while waste products are expelled. The cell membrane is composed of a phospholipid bilayer, which creates a barrier that is fluid and dynamic, allowing for the movement of certain molecules based on size, polarity, and concentration gradients.

Transport mechanisms such as diffusion, osmosis, and active transport enable the cell to control the internal environment effectively. This regulatory role is crucial for the cell's survival, enabling it to respond to changes in the external environment and maintain cellular functions. The other options pertain to other cellular organelles or processes; for example, ATP production occurs in the mitochondria, protein modification and packaging take place in the endoplasmic reticulum and Golgi apparatus, and cell division is facilitated by the cytoskeleton and other structures. These functions are distinct from the primary role of the cell membrane in regulating transport.