Name the main component of plant cell walls.

The primary component of plant cell walls is cellulose. Cellulose is a polysaccharide made up of long chains of glucose units, and it provides structural support and rigidity to plant cells. It is the most abundant organic polymer on Earth and plays a crucial role in maintaining the shape and integrity of plant cells, allowing them to withstand various physical stresses.

In the context of plant structure, cellulose chains form microfibrils that are synthesized by the plant cell membrane and are a major component of the cell wall matrix. This configuration helps store energy and facilitates the transport of nutrients and water through the cell walls.

Other substances mentioned, such as lignin, although they do play important roles in certain types of plant structures (like the secondary walls of woody plants), are not the main component of all plant cell walls. Chitin is a polymer found in fungal cell walls and arthropod exoskeletons, and collagen is a protein primarily found in animal connective tissues, not in plants. Hence, cellulose stands out as the defining component of plant cell walls.