* Cell wall: This is a rigid outer layer that provides structure and support to the cell. It's made primarily of cellulose and is found outside the cell membrane.

* Cell membrane: This is a thin, flexible layer that surrounds the cytoplasm of the cell. It controls what enters and exits the cell and plays a role in communication.

So, it's not a case of one replacing the other. Both structures are present and work together to ensure the proper functioning of the plant cell.