Final answer:
The stacked flattened sacks of membranes scattered throughout the cytoplasm in plant cells are known as the Golgi apparatus. It resembles stacked deflated balloons and is responsible for processing and distributing substances within the cell.
Step-by-step explanation:
Stacks of flattened sacks of membranes scattered throughout the cytoplasm of a plant cell are known as the Golgi apparatus. The Golgi apparatus is involved in modifying, sorting, and packaging various substances for secretion out of the cell or for use within the cell. It operates similarly to a post office in the way it labels and distributes "packages" throughout the cell. Both animal and plant cells contain a Golgi apparatus, and in plant cells, they are especially involved with synthesizing cell wall polysaccharides.
The Golgi apparatus comprises a series of flattened, membrane-covered discs called cisternae, which somewhat resemble a stack of deflated balloons. The structure is often found close to the cell nucleus and works in concert with the endoplasmic reticulum by receiving proteins and other molecules, which it then further processes. After processing, pieces of the Golgi membrane pinch off to form vesicles that transport molecules to their required location in the cell.