AP BIOLOGY

Detailed explanation-1: -The cell membrane is called selectively permeable as it only allows specific molecules to pass. Only specific molecules like water and gaseous molecules can pass through the cell membrane directly. It stops the flow of other molecules towards the two sides.

Detailed explanation-2: -The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids. Ions such as H+ or Na+ cannot.

Detailed explanation-3: -A selectively-permeable membrane is a membrane that allows only some substances and molecules to pass into or leave the cell. An example of a selectively-permeable membrane is the cell membrane. It allows the passage of only certain types of molecules through diffusion and occasionally by facilitated diffusion.

Detailed explanation-4: -The plasma membrane is called as selectively permeable membrane because it regulates the movement of substances in and out of the cell. It means that the plasma membrane allows some material to pass through it while at the same time it blocks other material from entering through it.