Final answer:
Lignin, pectins, and gums are binding substances that have important roles in cell walls and the digestive system. They provide strength, structure, and bulk, and affect nutrient absorption.
Step-by-step explanation:
Lignin, pectins, and gums are binding substances that play important roles in cell walls and the digestive system. Lignin is a rigid material found in the secondary cell wall of vascular plants, providing strength and resistance to gravity. Pectins and gums are polysaccharides that bind to cellulose or chitin fibers, connecting them to each other and providing structure to the cell wall. In the digestive system, lignin, along with other dietary fibers, adds bulk to the food and eases bowel movements, while pectins and gums alter the nature of the gastrointestinal tract and affect the absorption of nutrients and chemicals.