What characteristics does a cell membrane have that the plastic bag does not have?

The characteristic that differentiates the cell membrane from a plastic bag is that the membrane is permeable to the passage of substances.

Explanation:

Cell membrane covers the cell and is predominantly formed by a double layer of lipids, which gives it the main characteristic of behaving as a semi-permeable membrane. This indicates that the membrane allows the entry of some substances and prevents the entry of others.

Unlike the cell membrane, a plastic bag is impermeable, preventing the passage of water or any other substance.