Final answer:
The cell wall is a rigid, protective layer made mainly of cellulose in plants, providing structural support and shape, while the cell membrane is a flexible, selective barrier that regulates substance flow and is involved in communication.
Step-by-step explanation:
The difference between the structure and function of the cell wall and the cell membrane lies in their composition and roles within the cell. The cell wall is a rigid covering found external to the cell membrane primarily in plant, fungal, and protistan cells, as well as in prokaryotic organisms. Its main function is to provide protection, structural support, and maintain the shape of the cell. The primary component of the plant cell wall is cellulose, a polysaccharide made of glucose units, giving it rigidity as experienced when biting into a vegetable like celery.
On the other hand, the cell membrane, also known as the plasma membrane, is found in all cells and is composed of a phospholipid bilayer with embedded proteins and cholesterol that contribute to its fluidity. The cell membrane acts as a selective barrier, regulating the entry and exit of materials and protecting the internal environment of the cell. Unlike the cell wall, the cell membrane is flexible and is involved in various cellular functions including communication and signaling.