Cell membrane is selectively permeable; it...

Cell membrane is selectively permeable; it...

• A. Produces energy
• B. Controls what enters and leaves the cell
• C. Holds the nucleus
• D. Synthesizes proteins

Answer: (B)

The cell membrane’s selective permeability means it acts as a gatekeeper, allowing some substances to cross while keeping others out. This control helps maintain the cell’s internal environment by letting in nutrients and oxygen and letting wastes exit, using transport proteins, channels, and pumps (some processes require energy). Energy production is done by mitochondria, the nucleus is enclosed by its own membrane, and proteins are made by ribosomes, not by the cell membrane. Because its main role is regulating entry and exit, this statement best describes what selective permeability does.

The cell membrane’s selective permeability means it acts as a gatekeeper, allowing some substances to cross while keeping others out. This control helps maintain the cell’s internal environment by letting in nutrients and oxygen and letting wastes exit, using transport proteins, channels, and pumps (some processes require energy). Energy production is done by mitochondria, the nucleus is enclosed by its own membrane, and proteins are made by ribosomes, not by the cell membrane. Because its main role is regulating entry and exit, this statement best describes what selective permeability does.