What ingredient is primarily used for its structure in plant cell walls?

Cellulose is the primary ingredient used for its structural role in plant cell walls. It is a complex carbohydrate made up of long chains of glucose molecules linked together. The unique structure of cellulose provides rigidity and strength to plants, allowing them to maintain their shape and resist external pressures. This is crucial for the overall integrity of plant tissues, as it helps them withstand various environmental conditions.

While fats, proteins, and carbohydrates play significant roles in plant biology, they do not serve the same structural function as cellulose. Fats primarily serve as energy storage and insulation, proteins are involved in a vast array of biochemical functions including enzyme activity and structural roles in cells, and although carbohydrates include cellulose, many are used for energy or storage rather than structural purposes. In contrast, cellulose is specifically designed to form a robust framework that supports the plant's overall structure, making it essential for the plant's growth and stability.