Question

why is plasma membrane called selectively permeable membrane

Answer 1

Plasma membrane is a outermost layer of the living cell.

It is a bi-lipid layer,consisting of a few protein molecule.

Plasma membrane is called as a selectively permeable membrane, because it allows only certain molecule to pass through the cell membrane. like oxygen,carbon dioxide,minerals some protiens etc 

It is highly selective in deciding which molecules are to be allowed to pass through the membrane .

Answer 2

Explanation:

The membrane that surrounds the organelles of the cell, by creating a barrier between cell organelles and the external environment is called the plasma membrane. It is also called a boundary of the cell.

It allows only certain molecules to pass through it.

It also prevents the movement of some other materials.

Hence plasma membrane is also called selectively permeable membrane.

Hope this helps.....