Question

why is the cell membrane is called semipremeable

Answer 1

semipermeable membrane is also called selectively permeable membraneor we can call it as partially permeable membrane.It allows only cetain materials to pass through it.so it is called semi permeable membrane.

Answer 2

Cell membrane is called semipermeable because  it allows only certain type of materials which is useful for the cell.So it is also called as selectively permeable.Not only sends the useful materials into the cell it also sends out the waste materials.It also gives the outside information to the cell.