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Vascular Tissues

 
4.1 Vascular Tissues
 
A diagram titled ‘The Necessity of Transport in Plants’ is shown. It features a central box with the title, connected to six surrounding boxes, each describing a specific function: 1. ‘Transport water and mineral salts to carry out photosynthesis and growth.’ 2. ‘Transport photosynthetic products to other parts of plants.’ 3. ‘Transport water for plant cell turgidity and for support.’ 4. ‘Transports water in plants for cooling.’ 5. ‘Transport phytohormones in plants for response.’ 6. ‘Transports organic acids in plants.’ The diagram is branded with the Pandai logo at the bottom right.
 
Introduction to Vascular Tissues
  • Plants are multicellular organisms which are formed from cells that need water and nutrients.
  • The large and tall size of the plants creates a total surface area that is insufficient for the plant to absorb its basic needs from the surroundings.
  • In order to overcome this problem, plants have vascular tissues to transport water, mineral salts and nutrients to all the cells.
  • Plants which have a transport system are known as vascular plants.
  • Non-vascular plants like alga and moss on the other hand, do not have any transport system.
  • Transport in plants is carried out by vascular tissues which consist of:
    • Xylem tissue: transport water and mineral salts from roots to shoots
    • Phloem tissue: transport photosynthetic product and other organic substances from shoots to other parts.
    • The xylem tissue contains xylem vessel and tracheid as the main transport vessels,whereas the phloem tissue contains sieve tube and companion cell as the main transport vessels.
 
The image is an infographic titled ‘The Similarities Between Xylem Tissue and Phloem Tissue.’ It is divided into three sections, each numbered from 1 to 3. 1. The first section states, ‘As vascular tissue.’2. The second section states, ‘Transport substance in plants.’ 3. The third section states, ‘Have parenchyma cell and fibres within the vascular tissue.’ At the bottom right corner, there is a logo for ‘Pandai.’
 
The Differences between Xylem Tissue and Phloem Tissue

 

Aspect Xylem Tissues
Main cell type 
  • Xylem vessel & tracheid.
Lignified wall
  • Lignified in the form of annular, spiral, scalariform, reticular and pit.
Condition of the cell after mature
  • Death cells and cell contents degenerated.
  • Cells form a long and hollow vessel.
  • Have plate or nnote for the flow of water & mineral.
  • Have pits for the glow of water and minerals laterally.
Materials transported
  • Water, minerals, salt & phytojhormones.
Main function
  • Transport water and mineral in plants.
  • Provide mechanical support to plants.

 

Aspect Phloem Tissues
Main cell type 
  • Sieve elemetns & companion cell.
Lignified wall
  •  Unlignified.
Condition of the cell after mature
  • Living vells with degenerated organelles.
  • Cells form a  long tube filled with cytoplasm.
  • Have sieve tubes for the flow of organic substance.
Materials transported
  • Sucrose, amino acid, organic acid, phytohormones & water.
Main function
  • Transport sucrose and other organic substances.

 
 
Structural Adaptations of Xylem Vessels and Tracheids to Transport Water and Mineral Salts
Xylem Vessel
  • Xylem vessel consists of dead cells at maturity which do not have cytoplasm.
  • These cells are arranged longitudinally from end to end to form a continuous tube to allow water flow from the roots to the leaves.
  • The walls of the xylem vessel have uneven lignin thickening to: 
    • Give strength to xylem vessels to prevent them collapsing due to the tension force and pressure changes when water moves through it.
    • Prevent the plant from being bent.
Tracheid
  • The cell wall of tracheid also has lignin thickening and pits to allow water movement to adjacent cells.
 
Structural Adaptations of Sieve Tubes and Companion Cells to the Transport of Organic Substances
  • Phloem tissues transport and distribute dissolved organic compounds such as sucrose, amino acids and plant hormones to all parts of the plant.
  • Phloem is a living cell because it has cytoplasm
  • Adapatation of sieve tubes and companion cells to their functions:
    • Sieve tubes do not have nuclei, ribosomes or vacuoles. This allows sucrose molecules to pass through sieve tubes easily.
    • On both ends of the sieve tube, there is a sieve plate that has pores through which organic compounds can flow from one sieve tube to the next.
    • Companion cells contain mitochondria to provide energy in the form of ATP to transport sucrose from the leaf to the sieve tube through active transport.
 

 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.
Chapter : Transportation in Plants
Topic : Vascular Tissues
Form 5 Biology
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