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The transport of substances in plants

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Ainul Husna Mohyedin
Ainul Husna Mohyedin

This document discusses transport processes in plants. It describes how: 1) Xylem vessels, tracheids and sieve tubes transport water and minerals from roots to leaves, while phloem transports organic substances like sugars from leaves to storage organs. 2) Translocation refers to the transport of dissolved organic solutes in the phloem from leaves (source) to roots and storage organs (sinks). 3) Transpiration is the loss of water vapor from leaves and involves the opening and closing of stomata to regulate water loss while allowing for gas exchange. Various environmental factors like light, temperature and humidity affect transpiration rate. 4) Water moves through the plant via root pressure,

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The Transport of Substances in Plants
2Bio Form 5 Chapter 1 Transport by AHM Transport organic substances from leaves to storage organs (roots, buds) Transport water and mineral salts absorbed in the roots, up the stem to the leaves
3Bio Form 5 Chapter 1 Transport by AHM -Xylem vessels -Tracheids -Parenchyma -Fibres ( a type of sclerenchyma) -sieve tube -Companion cell -Parenchyma -fibres
Translocation • The transport of dissolved organic solutes (sugar sucrose, amino acids, metabolites) in the phloem • Important for plant’s survival & enables organic substances eg sucrose to be stored or converted to other sugar • Translocated downward from leaves to storage organs ( roots, growing region and buds) 4Bio Form 5 Chapter 1 Transport by AHM
Translocation – from SOURCE (leaf cell to SINK (root cell) Bio Form 5 Chapter 1 Transport by AHM 5
Transpiration • Loss of water vapour from a living plant due to evaporation • Take place through stomata & lenticels • Importance of transpiration : – helps in the absorption & transport of water and mineral ions from the roots to other parts of the shoots Bio Form 5 Chapter 1 Transport by AHM 6
Transpiration • Transpiration stream = the continuous stream of flowing water from the roots to the leaves Bio Form 5 Chapter 1 Transport by AHM 7
The Process of Transpiration Roots  xylem vessels  leaves (mesophyll cells) Bio Form 5 Chapter 1 Transport by AHM 8 -Surface of mesophyll cells are covered by a thin layer of water -Air space is saturated with water vapour as the Sun heat the external surface -[H20 vapour] in atmosp. Is lower than water vapour in air space  water evaporates from leaves -The loss of water make the mesophyll hypertonic as compared to an adjacent cell -Water from adjacent cell diffuse -Create transpirational pull
The External Conditions that affects the rate of transpiration Bio Form 5 Chapter 1 Transport by AHM 9 Light intesity Temperature Relative Humidity Air movement
Bio Form 5 Chapter 1 Transport by AHM 10
The Movement of Water from soil  leaves • Movement of water through the roots Bio Form 5 Chapter 1 Transport by AHM 11 •Water enter from soil to roots cells through osmosis [cytoplasm of root hair cells are hypertonic compared to the surrounding soil water] • the cell hypertonic compared to adjacent cells • water diffuse into adjancent cells •Water move inwards to cortex •Cortex = cytoplasm, vacuole, cell wall of parenchyma cells =until endodermis
- Via cell wall is blocked by Casparian strip at endodermis (impermeable to water) Bio Form 5 Chapter 1 Transport by AHM 12
• Root pressure = results in the upward push of water & mineral ions into the xylem of the stem • The gradient of water concentration that exists across the cortex creates a pushing force that results the inflow of water into the xylem Bio Form 5 Chapter 1 Transport by AHM 13
• Small plants = the root pressure can push water all the way up to stem and hydathodes @ edges of leaves  GUTTATION • Occurs on cool humid mornings Bio Form 5 Chapter 1 Transport by AHM 14
The Movement of Water from soil  leaves • Movement of water through the stem Bio Form 5 Chapter 1 Transport by AHM 15 -Adhesive and cohesive properties of water molecules -Xylem are long, narrow & hollow column of water and creates capillarity / capillary action -Water molecule adhere to one another = cohesive force -Water molecule adhere to the xylem vessels = adhesive forces -Due to hydrogen bonding
The Movement of Water from soil  leaves • Movement of water from LEAVES to ATMOSPHERE Bio Form 5 Chapter 1 Transport by AHM 16 -Transpirational pull = force due to the water cohesive properties that draw water from the xylem of the leaves and stems and eventually from the xylem in the roots Root pressure, the adhesive and cohesive properties of water (capillary action) and the transpirational pull contribute to the movement of water from roots to the leaves
The Regulation of transpiration by the stomata Bio Form 5 Chapter 1 Transport by AHM 17
The Regulation of transpiration by the stomata Bio Form 5 Chapter 1 Transport by AHM 18

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The transport of substances in plants

  • 2. 2Bio Form 5 Chapter 1 Transport by AHM Transport organic substances from leaves to storage organs (roots, buds) Transport water and mineral salts absorbed in the roots, up the stem to the leaves
  • 3. 3Bio Form 5 Chapter 1 Transport by AHM -Xylem vessels -Tracheids -Parenchyma -Fibres ( a type of sclerenchyma) -sieve tube -Companion cell -Parenchyma -fibres
  • 4. Translocation • The transport of dissolved organic solutes (sugar sucrose, amino acids, metabolites) in the phloem • Important for plant’s survival & enables organic substances eg sucrose to be stored or converted to other sugar • Translocated downward from leaves to storage organs ( roots, growing region and buds) 4Bio Form 5 Chapter 1 Transport by AHM
  • 5. Translocation – from SOURCE (leaf cell to SINK (root cell) Bio Form 5 Chapter 1 Transport by AHM 5
  • 6. Transpiration • Loss of water vapour from a living plant due to evaporation • Take place through stomata & lenticels • Importance of transpiration : – helps in the absorption & transport of water and mineral ions from the roots to other parts of the shoots Bio Form 5 Chapter 1 Transport by AHM 6
  • 7. Transpiration • Transpiration stream = the continuous stream of flowing water from the roots to the leaves Bio Form 5 Chapter 1 Transport by AHM 7
  • 8. The Process of Transpiration Roots  xylem vessels  leaves (mesophyll cells) Bio Form 5 Chapter 1 Transport by AHM 8 -Surface of mesophyll cells are covered by a thin layer of water -Air space is saturated with water vapour as the Sun heat the external surface -[H20 vapour] in atmosp. Is lower than water vapour in air space  water evaporates from leaves -The loss of water make the mesophyll hypertonic as compared to an adjacent cell -Water from adjacent cell diffuse -Create transpirational pull
  • 9. The External Conditions that affects the rate of transpiration Bio Form 5 Chapter 1 Transport by AHM 9 Light intesity Temperature Relative Humidity Air movement
  • 10. Bio Form 5 Chapter 1 Transport by AHM 10
  • 11. The Movement of Water from soil  leaves • Movement of water through the roots Bio Form 5 Chapter 1 Transport by AHM 11 •Water enter from soil to roots cells through osmosis [cytoplasm of root hair cells are hypertonic compared to the surrounding soil water] • the cell hypertonic compared to adjacent cells • water diffuse into adjancent cells •Water move inwards to cortex •Cortex = cytoplasm, vacuole, cell wall of parenchyma cells =until endodermis
  • 12. - Via cell wall is blocked by Casparian strip at endodermis (impermeable to water) Bio Form 5 Chapter 1 Transport by AHM 12
  • 13. • Root pressure = results in the upward push of water & mineral ions into the xylem of the stem • The gradient of water concentration that exists across the cortex creates a pushing force that results the inflow of water into the xylem Bio Form 5 Chapter 1 Transport by AHM 13
  • 14. • Small plants = the root pressure can push water all the way up to stem and hydathodes @ edges of leaves  GUTTATION • Occurs on cool humid mornings Bio Form 5 Chapter 1 Transport by AHM 14
  • 15. The Movement of Water from soil  leaves • Movement of water through the stem Bio Form 5 Chapter 1 Transport by AHM 15 -Adhesive and cohesive properties of water molecules -Xylem are long, narrow & hollow column of water and creates capillarity / capillary action -Water molecule adhere to one another = cohesive force -Water molecule adhere to the xylem vessels = adhesive forces -Due to hydrogen bonding
  • 16. The Movement of Water from soil  leaves • Movement of water from LEAVES to ATMOSPHERE Bio Form 5 Chapter 1 Transport by AHM 16 -Transpirational pull = force due to the water cohesive properties that draw water from the xylem of the leaves and stems and eventually from the xylem in the roots Root pressure, the adhesive and cohesive properties of water (capillary action) and the transpirational pull contribute to the movement of water from roots to the leaves
  • 17. The Regulation of transpiration by the stomata Bio Form 5 Chapter 1 Transport by AHM 17
  • 18. The Regulation of transpiration by the stomata Bio Form 5 Chapter 1 Transport by AHM 18