The rigid boundary that gives plant cells shape is called the cell wall; what is it made of?

• A. Cell Wall (cellulose)
• B. Cell Membrane (phospholipid bilayer)
• C. Cytoskeleton
• D. Vacuole

Answer: (A)

Plant cell walls owe their rigidity to cellulose. Cellulose is a long chain of glucose units linked by β-1,4 glycosidic bonds, which bundle together into strong microfibrils. These microfibrils form a network that, along with other polysaccharides like hemicellulose and pectin (and sometimes lignin in secondary walls), creates a sturdy, resistant structure that helps maintain cell shape and protect the cell. The cell membrane is the flexible lipid bilayer that encloses the cell interior, the cytoskeleton provides internal support and organization, and the vacuole helps regulate pressure inside the cell; none of these form the rigid boundary itself.