What structure is found in all cells that encloses the cell to form the outside?

That's called the cell membrane. It encloses both prokaryotic, eukaryotic, plant and animal cells.

In the case of eukaryotic cells, it is the outermost layer, in the case of prokaryotic cells, it is not.

Hope it helped,

BioTeacher101

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck