AP BIOLOGY

Detailed explanation-1: -Answer and Explanation: The cell membrane allows all substances into the cell. The cell membrane is selectively permeable. This means that it only allows the entrance/exit of certain molecules.

Detailed explanation-2: -They are semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot. Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly. Small polar molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly.

Detailed explanation-3: -The cell membrane is selectively permeable, allowing only a limited number of materials to diffuse through its lipid bilayer. All materials that cross the membrane do so using passive (non-energy-requiring) or active (energy-requiring) transport processes.

Detailed explanation-4: -The cell membrane is the outer layer of the cell. The primary function of the cell membrane is to regulate what substances enter and leave the cell. The cell membrane is selectively permeable, or “semi-permeable", meaning that the membrane only allows certain substances to enter or leave the cell.