The primary function of cellulose in plant cells is to provide structural support and maintain the shape of the cell. Cellulose is a complex carbohydrate that forms a rigid cell wall, allowing plants to withstand various stresses, such as wind and water. It also plays a critical role in regulating the flow of materials and providing protection against pathogens. Additionally, cellulose is an essential component of dietary fiber for humans, contributing to digestive health. The renewable nature of cellulose also makes it an important material in various industries, including the production of paper and textiles.