Final answer:
Cellulose is a polysaccharide that contributes to building and repairing tissues, found in the cell walls of plants. It provides structural support, essential for plant growth and rigidity, while lignin adds stiffness to vascular plant tissues.
Step-by-step explanation:
The substance that plays a role in building and repairing tissues, especially in the formation of cell walls, is cellulose. This complex carbohydrate, or polysaccharide, provides essential structural support to plant cells. Cellulose is significant to plant growth and rigidity, making it an integral component of the cell wall. In addition to cellulose, the cell wall contains a protein that may assist enzymatic changes necessary for cellular growth.
Lignin is another important component found in the cell walls of vascular plants, providing rigidity and allowing plants to grow tall. Unlike cellulose, lignin is highly resistant to degradation due to its phenolic structure. This contributes to the stiffness of plant tissues, especially in wood. Carbohydrates, including cellulose and lignin, along with proteins, are crucial for maintaining structural integrity in organisms.