Which structure serves as a protective barrier for plant cells?

The cell wall serves as a protective barrier for plant cells by providing structure and rigidity. Composed primarily of cellulose, the cell wall not only helps maintain the shape of the cell but also offers protection against mechanical stress, pathogens, and excessive water loss. Additionally, it regulates the movement of substances into and out of the cell, contributing to homeostasis within the plant.

In contrast, the cell membrane, while also crucial for protecting the cell and controlling the passage of materials, is more flexible and is found in all types of cells, including animal cells. The plasma and nucleus do not serve a protective role in the same manner as the cell wall. The nucleus is primarily involved in housing genetic material and regulating various cell activities. Thus, the significance of the cell wall as a protective structure is integral to the overall function and health of plant cells.