USA Biology Olympiad (USABO) Practice Exam

Sclerenchyma cells play a critical role in supporting the plant body due to their structural characteristics. These cells are typically thick-walled and often contain lignin, which provides rigidity and strength. There are two main types of sclerenchyma cells: fibers, which are long and slender, and sclereids, which are typically shorter and more irregular in shape. By providing mechanical support, sclerenchyma cells enable plants to maintain their structure, resist external stresses, and support the weight of larger structures, such as leaves and flowers. This support is essential for plants to grow upright and reach towards sunlight, which is vital for their photosynthesis process. Additionally, the robustness provided by sclerenchyma cells allows plants to withstand various environmental conditions, such as wind and gravity, thus contributing significantly to plant survival and overall fitness. In contrast, other options do not align with the primary function of sclerenchyma. For example, while some cells are involved in nutrient transport or water storage, these functions are typically associated with other specialized cell types, such as parenchyma or xylem and phloem cells. Similarly, photosynthesis is carried out mainly by mesophyll cells in leaves, not by sclerenchyma