While the analogy of sap being the "blood" of a tree is commonly used, it's important to note that this comparison has its limitations. Unlike blood in animals, which circulates to transport nutrients and oxygen, sap primarily moves nutrients and sugars within a tree. Sap is a fluid that contains water, minerals, sugars, and other substances essential for the tree's growth and metabolism. While the analogy captures the vital role of sap in a tree's life, it's not an exact biological parallel.