Transportation in Plants: Meaning and Definition, Xylem and Phloem
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Meaning and Definition of Transportation
The process involving the movement of water along with necessary nutrients to all parts of the plant for its survival.
Transportation involves transporting water, minerals, and food to all parts of the plant body.
It is a vital process in plants.
Xylem and Phloem act as the circulatory system that transports blood throughout the human body.
Transportation in Plants
Xylem
The water and mineral salts from the roots up to other parts of the plant is carried out by Xylem.
Lignin is the woody material having tough walls.
Transpiration stream is the process involved.
Mature xylem consists of:
Elongated dead cells.
Arranged end to end to form continuous vessels (tubes).
There is no cytoplasm and are impermeable to water.
Xylem provides mechanical support.
It is in the center of the vascular bundle, deep in the plant.
Dead cells are the only (parenchyma is the only living cells present in the xylem).
Phloem
It is responsible for transporting sucrose and amino acids.
This transportation occurs between the leaves and other parts of the plant.
Translocation is the process involved.
It consists of living cells arranged end to end.
It contains cytoplasm which goes through holes from one cell to the next.
They contain living cells (fibers are the only dead cells in the phloem).
It doesn’t provide mechanical support.
Transportation Occurs in Three Levels
Substance transportation from cell to another.
Within phloem and xylem, there is a long-distance transportation of sap.
Solute and water release along with uptake by individual cells.
Means of Transportation in Plants
Means of Transportation in Plants
Diffusion
There is a passive movement of a substance from cell-to-cell or from one plant part to the cell.
Movement of molecules is in a random manner and it is a slow process.
The movement of substance is from higher concentration to lower concentration region.
The rate of diffusion depends on:
Temperature
Pressure
A gradient of concentration.
Facilitated Diffusion
It is a passive process that comprises antiport, uniport, and symport.
As compared to larger substances a smaller substance must be diffused faster.
The uniport protein carries single solute across the membrane.
The Symport proteins transfer two different solutes simultaneously in the same direction.
Active Transport
The energy of ATP is used to drive the pump.
A phosphate to a gateway molecule is donated which is responsible for pumping the desired molecule across the membrane.