A cell membrane is found in both plant and animal cells. It's a fundamental structure common to all living cells.

Here's why:

* Function: The cell membrane acts as a barrier, controlling what enters and exits the cell. This is crucial for maintaining the cell's internal environment and carrying out essential processes.

* Structure: Both plant and animal cell membranes are composed of a phospholipid bilayer, which forms a flexible and selectively permeable barrier.

So, while plants have additional structures like cell walls, both plant and animal cells rely on a cell membrane for their survival.