One proposed project to restore louisiana wetlands is to backfill canals that were built for access to and transportation of oil from the coastal area. why might scientists first want to build and study a model of their proposed object?

Scientists would probably want to model this first so they will identify the outcome instead of creating a large catastrophe. It wouldn't be an upright idea for scientists to begin a project without knowing if it will work, the consequence, and if it’s safe to do on the land. 

substitution is the answer in this case

answer:

the water molecules are transferred from the roots to the stem or top parts of the tall tree because of important properties of water which are adhesion, cohesion and capillary action. cohesion is the property of water molecules keeps water molecules in a combined state by sharing of bonds between them at the atomic level. adhesion allows the interaction of water molecules with other substances or substrate. adhesion will cause the attachment of water molecules to the wall of the vessel (xylem) of the plant. capillary action occurs when the adhesive force to the vessel wall is stronger than the cohesive force between water molecules. capillary action mimics the transfer of water from a tube or pipe. in this way water utilizes its property to transfer water from down to top level of the plant.