Question

fill in the blank with the organelle that performs this function. the choose your answer... is the structure that separates the inside & the outside of a cell.

Explanation:

The cell membrane (or plasma membrane) is the organelle (or structure, as it's a membrane - bound structure in cells) that acts as a barrier, separating the internal environment of the cell from the external environment. It controls the passage of substances in and out of the cell.

Answer:

cell membrane (or plasma membrane)