Water Transport in a Plant By: Ghaida Odah 8C

Introduction We all know that plants need water to grow and live. What we might not know is how that water that is first put in the soil moves up the plant and all the way to the leaves. In this presentation you will learn all about how water in transported in plants and the importance of movement of the water in plants.

Step 1 The major path for water movement into plants is from soil to roots. Water enters near the tip of a growing root, the same region where root hairs grow. The surface of the root hairs need to be in close contact with the soil to access soil water. Water diffuses into the root, where it can take at least three different pathways to eventually reach the xylem, the conduit located at the interior of the root that carries the soil water to the leaves.

Apoplastic Path One of the 3 paths that the water can travel through in order to reach the xylem is the aoplastic path. In the apoplastic path, water travels through the apoplast which is the cell wall region. It travels between the cells never crossing the membranes.

Transmembrane Path In the transmembrane path, water travels straight through the cells of the cortex to the endodermis by entering a cell on one side and exiting on the other side, In this path, water crosses at least two membranes for each cell in its path.

Symplastic Path In the symplastic path, water travels through the symplast which is the part of the cell bound by a membrane. It uses plasmodesmatal connections between the cells.

Step 2 Once at the endodermis, each water molecule is forced to move across cell membranes in order to enter th endodermal cells because the lipophilic Casparian strip surrounding the endodermal cells is a barrier. While the water following the transmembrane and symplastic paths travel past the Casparian strip easily, the water that takes the apoplastic path cannot move around cells anymore and therefore must enter the cell by crossing its membrane because of the strip.

Step 3 After the water molecules bypass the Casparian Strip, they enter the Stele and travel into the xylem. The water enters the xylem through pits in the xylems vessels or tracheids. Then, water joins the upward flow of water through the vessel elements and tracheids to reach the stems and leaves of the plant.

Transpiration Once the water reaches the leave sin a plant transpiration occurs. Transpiration is the evaporation of water from plants. It occurs chiefly at the leaves while their stomata are open for the passage of CO 2 and O 2 during photosynthesis.

Thank You!