Question

Which structure regulates the transport of substances in and out of a cell?

A. The cell membrane
B. The cell's cytoplasm
C. The cell wall
D. The nuclear membrane

Answer 1

The cell membrane, known for its selective permeability, is the structure that regulates the transport of substances in and out of a cell.

Step-by-step explanation:

The Role of the Cell Membrane in Substance Transport

The structure that regulates the transport of substances in and out of a cell is A. The cell membrane. The plasma membrane, which is another name for the cell membrane, encapsulates the cell's cytoplasm, defining the cell's boundary. Unlike the cell wall that mainly provides support or the nuclear membrane that encloses the genetic material, the cell membrane has a unique property of selective permeability, enabling it to control the exchange of substances with the external environment. It does this by allowing certain molecules to pass through while blocking others, effectively regulating the concentration of ions, nutrients, and waste products within the intracellular space.

Transport through the cell membrane ensures that cells maintain proper concentrations of essential molecules like calcium, sodium, potassium, and chloride ions. Additionally, it helps in the uptake of necessary nutrients and the expulsion of carbon dioxide and other metabolic wastes, facilitating the cell's homeostasis. The function of the cell membrane is fundamental to cellular life, supporting various processes like cell adhesion, signaling, and maintaining structural integrity.

Answer 2

The cell membrane structure regulates the transport of substances in and out of a cell.

The correct option is A.

Step-by-step explanation:

The structure responsible for regulating the transport of substances in and out of a cell is the cell membrane, also known as the plasma membrane. It acts as a semi-permeable barrier, controlling the movement of molecules and ions to maintain cellular homeostasis and facilitate the exchange of essential substances.

The cell membrane, or plasma membrane, is the biological structure that plays a crucial role in regulating the transport of substances into and out of a cell. This membrane is often described as semi-permeable, meaning it selectively allows certain molecules or ions to pass through while restricting others. This selective permeability is essential for maintaining cellular homeostasis, as it controls the internal environment of the cell.

The cell membrane is primarily composed of a lipid bilayer embedded with proteins. The lipid bilayer provides a barrier that separates the internal and external environments of the cell. The proteins within the membrane serve various functions, including acting as channels, carriers, receptors, and enzymes involved in different aspects of cellular transport and signaling.

As substances move across the cell membrane, they may do so through passive processes like diffusion or facilitated diffusion, or through active processes like active transport. The regulation of these processes ensures that the cell receives necessary nutrients, expels waste products, and maintains an optimal internal environment for cellular activities.

So, the correct option is A.