What is the role of the cell membrane?

The role of the cell membrane is primarily to control the movement of substances in and out of cells. This crucial function is achieved through its structure, which is composed of a phospholipid bilayer with embedded proteins. This arrangement allows the membrane to be selectively permeable, meaning it can regulate what enters and exits the cell based on factors like size, charge, and solubility.

The proteins in the membrane facilitate transport processes, such as passive transport (diffusion and osmosis) and active transport (requiring energy), enabling the cell to maintain homeostasis. By controlling the internal environment of the cell, the membrane plays a significant role in communication, nutrient uptake, and waste elimination, which are vital for the cell's survival and function.

In contrast to the other functions listed, protein synthesis, storage of genetic material, and energy production are carried out by different cellular structures and processes. Ribosomes and the endoplasmic reticulum are involved in protein synthesis, the nucleus houses the genetic material, and mitochondria are primarily responsible for energy production. Therefore, option B accurately reflects the essential function of the cell membrane.