Which term refers to the outer layer of a cell?

The term that refers to the outer layer of a cell is the cell membrane. The cell membrane serves as a protective barrier that surrounds the cell, controlling what enters and exits. It is primarily composed of a lipid bilayer, which provides flexibility and structural integrity, while also containing proteins that facilitate communication and transport.

The cell membrane plays a crucial role in maintaining homeostasis, allowing selective permeability so that essential nutrients can enter while waste products can exit. It also contains receptors for signaling molecules, enabling the cell to respond to its environment. Understanding the function and structure of the cell membrane is vital for comprehending how cells interact with their surroundings and maintain their internal conditions.

In contrast, the nucleus is the cell's control center housing genetic material; the cytoplasm is the gel-like substance within the cell where various organelles are located; and ribosomes are the sites of protein synthesis. Each of these components has distinct functions that contribute to the overall operation of the cell, but none serves as the outer layer.