Question

what would happen if plasma membrane ruptures or breaks down ?​

Answer 1

If the plasma membrane ruptures or breakdown then the cell will not be able to exchange material from its surrounding by diffusion or osmosis. Thereafter the protoplasmic material will be disappeared and the cell will die

Answer 2

The plasma membrane is phospholipid bilayer whose main function is to act as a boundary between the contents of the cell and the exterior environment. If the plasma membrane ruptures, the contents of the cell would be ejected into the outside environment and the cell would no longer be able to function, so it would die. Surrounding WBC's would engulf the material and use it to repair other cells.