Ace the ISA Certified Arborist Test 2025 – Branch Out and Conquer Your Career!

Cellulose plays a critical role in the structure of trees by providing structural support in cell walls. It is a complex carbohydrate that makes up a significant portion of the cell wall in plant cells, particularly in woody plants like trees. The arrangement of cellulose fibers gives the cells rigidity and strength, which is essential for trees to maintain their shape and withstand various environmental stresses, such as wind and gravity. This structural support is vital for the overall integrity of the tree, allowing it to grow tall and support its leaves and branches, which are necessary for photosynthesis and overall health.

The other options do not accurately describe the function of cellulose. While trees do have storage carbohydrates such as starch, cellulose is not used for storage. It does not play a direct role in nutrient absorption, as that function is primarily carried out by root systems and associated mycorrhizae. Additionally, cellulose is not related to chlorophyll, which is the pigment involved in photosynthesis, made up of different organic compounds altogether. Thus, the correct answer highlights cellulose's fundamental role in providing structural support to trees.