What structure controls the movement of substances in and out of a cell?

What structure controls the movement of substances in and out of a cell?

• A. Endoplasmic reticulum
• B. Cytoplasm
• C. Cell membrane
• D. Nucleus

Answer: (C)

The cell membrane, also known as the plasma membrane, is the structure that controls the movement of substances into and out of a cell. It acts as a selective barrier, allowing certain molecules to pass while preventing others, thus maintaining homeostasis within the cell. The cell membrane is composed of a phospholipid bilayer with embedded proteins that facilitate transport, signaling, and communication between the cell and its environment. The endoplasmic reticulum is involved in the synthesis and processing of proteins and lipids, but it does not primarily function as a barrier for substance movement in and out of the cell. Cytoplasm refers to the jelly-like substance that fills the cell and contains organelles, but it is not involved in the selective transport of materials across the cell boundary. The nucleus is responsible for storing genetic material and coordinating activities related to growth, metabolism, and reproduction, but it does not directly control the movement of substances across the cell membrane. Thus, the cell membrane is the key player in regulating the internal environment of the cell through selective permeability.

The cell membrane, also known as the plasma membrane, is the structure that controls the movement of substances into and out of a cell. It acts as a selective barrier, allowing certain molecules to pass while preventing others, thus maintaining homeostasis within the cell. The cell membrane is composed of a phospholipid bilayer with embedded proteins that facilitate transport, signaling, and communication between the cell and its environment.

The endoplasmic reticulum is involved in the synthesis and processing of proteins and lipids, but it does not primarily function as a barrier for substance movement in and out of the cell.

Cytoplasm refers to the jelly-like substance that fills the cell and contains organelles, but it is not involved in the selective transport of materials across the cell boundary.

The nucleus is responsible for storing genetic material and coordinating activities related to growth, metabolism, and reproduction, but it does not directly control the movement of substances across the cell membrane.

Thus, the cell membrane is the key player in regulating the internal environment of the cell through selective permeability.