Explain the mechanism of transport of water in plants.
Explain the mechanism of transport of water in plants.
Xylem
The xylem is the known type of vascular tissue responsible for the transport of water and minerals. The components of the xylem are xylem vessels, tracheids, xylem fibres and xylem parenchyma.
Mechanism of transport of water in plants
The transport of water in plants involves two distinct processes:
- Absorption of water
- Ascent of sap (i.e., upward movement of water)
Absorption of water
The root hairs initially absorb water through diffusion. Root hairs are thin, slender extensions of epidermal cells. Once absorbed by the root hairs, water starts to move deeper and finally reaches the xylem either through the apoplast or symplast pathway.
Ascent of Sap
The upward movement of water from the root to the tip of shoots, leaves and branches is called the ascent of sap. Two factors regulate this movement:
- Root pressure is the pressure developed when the roots absorb excess water by an active process. Due to this, the pre-existing water is pushed upward along the length of the stem to a small height.
- Transpiration pull: Transpiration is the loss of water in the form of water vapor. Continuous transpiration occurring in all of the leaves of a plant creates a negative pressure in the water column (xylem). This exerts an upward pull on the water column, called transpiration pull. And thus, the water present in the xylem column transports up to the tip of the stem, leaves, etc.
Xylem
The xylem is the known type of vascular tissue responsible for the transport of water and minerals. The components of the xylem are xylem vessels, tracheids, xylem fibres and xylem parenchyma.
Mechanism of transport of water in plants
The transport of water in plants involves two distinct processes:
- Absorption of water
- Ascent of sap (i.e., upward movement of water)
Absorption of water
The root hairs initially absorb water through diffusion. Root hairs are thin, slender extensions of epidermal cells. Once absorbed by the root hairs, water starts to move deeper and finally reaches the xylem either through the apoplast or symplast pathway.
Ascent of Sap
The upward movement of water from the root to the tip of shoots, leaves and branches is called the ascent of sap. Two factors regulate this movement:
- Root pressure is the pressure developed when the roots absorb excess water by an active process. Due to this, the pre-existing water is pushed upward along the length of the stem to a small height.
- Transpiration pull: Transpiration is the loss of water in the form of water vapor. Continuous transpiration occurring in all of the leaves of a plant creates a negative pressure in the water column (xylem). This exerts an upward pull on the water column, called transpiration pull. And thus, the water present in the xylem column transports up to the tip of the stem, leaves, etc.
