Answer:
The cell wall is a rigid, protective layer that surrounds the cell membrane of plant, fungal, and bacterial cells. The primary function of the cell wall is to provide structural support and protection to the cell. It helps to maintain the shape of the cell and provides resistance against mechanical stress and osmotic pressure.
In addition to its structural role, the cell wall also plays a role in regulating the movement of substances into and out of the cell. It controls the diffusion of molecules, nutrients, and waste products, and prevents the entry of harmful substances.
The composition of the cell wall varies depending on the type of organism. In plants, the cell wall is primarily composed of cellulose, hemicellulose, and lignin, while in bacteria, it is composed of peptidoglycan. Fungal cell walls are composed of chitin, glucans, and other polysaccharides.