Plants transport food mostly in the form of disaccharides like sucrose but humans transport them in the form of a monosaccharide - glucose.
What is the reason behind this ?
One of the reasons could be -
humans and many other animals have active circulatory systems, there is little need for targeting sugars for specific parts of the body. The entire body would rapidly reach equilibrium with the glucose level of the bloodstream, and thus there likely never evolved the need to target specific organs to receive sugars via disaccharides
Source : This
Other reason could be that disaccharides are harder to transfer inside the cells than monosaccharides.