Question

why the cell membrane Is called selectively permeable membrane

Answer 1

All cells are enclosed with a cell membrane. A selectively permeable cell membrane is one that allows certain molecules or ions to pass through it by means of active or passive transport. Active transportprocesses require the cell to expend energy to move the materials, while passive transport can be done without using cellular energy. It is important to note that the membrane can also block the passage of materials depending on the conditions inside or outside of the cell.

The method used by a cell to pass molecules in or out is determined by the size of the molecule, as well as the concentration of the molecules on the inside and outside of the cell. Most cell membranes are covered with tiny protein channels that allow things to move in and out of the cell. These channels act as gateways.

If a molecule is tiny enough to fit through a special protein channel in the plasma membrane, it will use a form of active or passive transport to move through. If the molecule is too large to fit through a protein channel, it will have to enter or exit the cell by forming a vesicle. A vesicle can be thought of like a tiny pouch that surrounds the molecule and ushers it through an opening in the cell membrane.

Answer 2

selectively permeable (Differentialy permeable)
which are normally semi permeable, but allow transport of certain solutes across it


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