8.1 Transport in Plants

Objective: State that water is absorbed by root hair cells.

Water uptake in plants is a crucial process for survival. This section focuses on how plants absorb water, starting with the role of root hair cells.

Root Hair Cells

Root hair cells are specialized epidermal cells located in the root cortex. They are extensions of the root epidermal cells and are directly in contact with the soil. Their primary function is to absorb water and mineral ions from the soil.

• Increased Surface Area: Root hairs significantly increase the surface area of the root, maximizing contact with soil particles.
• Thin Cell Walls: The cell walls of root hair cells are thin, facilitating the movement of water across the cell membrane.
• Apoplast and Symplast Pathways: Water can move through the root cortex via two main pathways: the apoplast and the symplast.

Water Absorption by Root Hair Cells

Water absorption by root hair cells occurs primarily through osmosis. The concentration of water in the soil is typically higher than the concentration of water inside the root hair cell. This difference in water potential causes water to move into the root hair cell by osmosis.

The water then moves from cell to cell through the apoplast (the cell walls and intercellular spaces) and eventually enters the symplast (the cytoplasm of the cells connected by plasmodesmata).

In summary, water is absorbed by root hair cells through osmosis, driven by the difference in water potential between the soil and the root hair cell. This absorbed water then moves into the vascular tissues of the plant for transport to the rest of the plant.