Here's why:
* Vesicles are small, membrane-bound sacs that transport substances within the cell or between cells.
* They are formed by budding off from existing membranes, like the plasma membrane or the Golgi apparatus.
* This budding process involves the membrane folding inwards and pinching off, creating a closed sac.
Therefore, a vesicle is the specific term for a sac formed from pieces of cell membrane.
