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

Transportation in Plants

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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

Diffusion Facilitated diffusion Active Transport

Means of Transportation in Plants

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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.