Here's why:

* Cell membrane: This is the outermost layer of a living cell, both plant and animal. It's a thin, flexible barrier that controls what goes in and out of the cell.

* Cell wall: This is a rigid structure that exists outside the cell membrane in plant cells. It provides structural support and protection.

So, while the cell wall is a defining characteristic of plant cells, it's not the first layer you encounter when approaching a plant cell. The cell membrane is always the outermost layer of a living cell.