Question

bio - 201 topic 2: cell physiology & tissues
practice it
what is the cell membrane?
a protective layer that covers the surface of a cell.
a region of a cell that synthesizes lipids and other molecules.
a barrier that separates the interior content of the cell from the outside environment.
a structure that stores genetic material in a cell.
a layer of protein that surrounds the nucleus of a cell.

Explanation:

The cell - membrane is a semi - permeable structure that acts as a barrier, separating the cell's interior from the external environment. It is not just a protective layer on the surface (though it has protective functions), not a region for lipid synthesis (that's the endoplasmic reticulum), not a structure for storing genetic material (that's the nucleus), and not a protein layer around the nucleus.

Answer:

A barrier that separates the interior content of the cell from the outside environment.