Why is the cell membrane semi-permiable?

Answer 1

By design ;

proteins residing within the membrane provide both passive pores (holes) in the membrane as well as active transport across the membrane.

Answer 2

The cell membrane is semi-permeable because it allows certain molecules to pass through while restricting the passage of others. This selective permeability helps maintain the internal environment of the cell by controlling the movement of substances in and out. It is made up of a phospholipid bilayer with embedded proteins that regulate the transport of molecules.

Answer 3

A cell membrane is considered semi-permeable because materials and fluids can pass in and out, however the access is restricted.