Here's why:

* All cells, whether plant, animal, bacterial, or fungal, have cell membranes. The cell membrane is a vital structure that acts as a barrier between the inside and outside of the cell.

* Plant cells have an additional layer called the cell wall, which is made of cellulose and provides structural support and protection. However, the cell membrane exists beneath the cell wall.

So, the cell membrane is essential for the proper functioning of all cells, including plant cells.