Plant Transport


Published on

Published in: Technology, Business
No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Plant Transport

  1. 1. Plant Transport <ul><li>Reason for transport system </li></ul><ul><li>Transport system in plants </li></ul><ul><li>Adaptations of xylem tissues </li></ul><ul><li>Adaptations of phloem tissues </li></ul><ul><li>Absorption of root hair cells </li></ul><ul><li>Water movement processes </li></ul><ul><li>Transpiration pull </li></ul><ul><li>Rate of transpiration </li></ul>
  2. 2. 1. Reason for transport system <ul><li>Unicellular organisms </li></ul><ul><ul><li>They can transport materials like oxygen and urea in and out of their bodies by diffusion or osmosis easily. </li></ul></ul><ul><li>Multicellular organisms </li></ul><ul><ul><li>Most of the cells inside the organisms are too far from the surface of their bodies and diffusion and osmosis are too slow to be relied on. </li></ul></ul><ul><ul><li>A transportation system is required for food and oxygen to be brought efficiently from one place to another. </li></ul></ul><ul><ul><li>Diffusion and osmosis would take place between the transport system and the cells. </li></ul></ul>
  3. 3. 2. Transport system in plants <ul><li>Xylem and Phloem tissues </li></ul><ul><ul><li>Xylems transport water and minerals salts (nitrates) from roots to leaves in a unidirectional motion </li></ul></ul><ul><ul><li>Phloems transport organic products (sucrose) from the leaves to all parts of the plant in a bidirectional motion </li></ul></ul><ul><li>Vascular bundles </li></ul><ul><ul><li>Xylem and Phloem tissues are arranged in vascular bundles. A cambium separates the xylems and phloems. </li></ul></ul><ul><ul><li>The cambium undergoes division to produce new xylems and phloems. </li></ul></ul>
  4. 4. 2. Diagrams of the system <ul><ul><li>Sites of xylem and </li></ul></ul><ul><ul><li>phloem tissues </li></ul></ul>
  5. 5. 3. Functions of Xylem tissues <ul><li>Support </li></ul><ul><ul><li>Consists of lignin to provide the plant with support </li></ul></ul><ul><li>Transport of water and nitrates </li></ul><ul><ul><li>Conducts water and dissolved mineral salts from the roots to all other parts of the plant </li></ul></ul>
  6. 6. 3. Formation of Xylem tubes <ul><li>The xylem cells die when they mature. The cross walls and cell contents will break down. </li></ul><ul><li>A hollow lumen will be left. There is no obstruction to the flow of water. </li></ul><ul><li>The walls of the cells are thickened with lignin. It causes the walls to be rigid, supporting the plant. </li></ul>
  7. 7. 3. Adaptations of Xylem tissues <ul><li>Absence cross walls </li></ul><ul><ul><li>Maintains a continuous lumen </li></ul></ul><ul><li>Protoplasm disintegrate </li></ul><ul><ul><li>Allows water to move efficiently </li></ul></ul><ul><li>Dead empty tube </li></ul><ul><ul><li>Maintains a continuous lumen </li></ul></ul><ul><li>Lignified walls </li></ul><ul><ul><li>Walls are rigid </li></ul></ul><ul><ul><li>Xylem will not collapse </li></ul></ul><ul><ul><li>Supports the plant </li></ul></ul>
  8. 8. 4. Adaptations of Phloem tissues <ul><li>Bi-directional sucrose flow </li></ul><ul><ul><li>Food can be transported to all parts of the plant </li></ul></ul><ul><li>Cross walls perforated by sieve tubes </li></ul><ul><ul><li>Single row of thin elongated walls with minute pores </li></ul></ul><ul><ul><li>Living cells to conduct the food in the tube </li></ul></ul><ul><li>Companion cell present </li></ul><ul><ul><li>Consists of protoplasm and mitochondria </li></ul></ul><ul><ul><li>Assists sieve tubes in transport of food </li></ul></ul><ul><ul><li>Provides energy required for active transport </li></ul></ul><ul><ul><li>When dead, sieve elements will die off </li></ul></ul>
  9. 9. 5. Root hair cells <ul><li>Plants absorb water and minerals from the soil through the root hairs. </li></ul><ul><li>Root hair cells absorb water and nitrates from the soil efficiently. </li></ul><ul><li>They help to hold the plant more firmly to the ground. </li></ul>
  10. 10. 5. Adaptations of root hairs <ul><li>Finger-like extensions </li></ul><ul><ul><li>Increases surface area to volume ratio </li></ul></ul><ul><ul><li>To absorb water and mineral salts at a faster rate </li></ul></ul><ul><li>Lower water potential </li></ul><ul><ul><li>Allow osmosis and diffusion of nitrates to take place </li></ul></ul><ul><li>Large vacuole </li></ul><ul><ul><li>To absorb as much water as it can hold </li></ul></ul><ul><li>Is a living cell </li></ul><ul><ul><li>Carries out respiration </li></ul></ul><ul><ul><li>This provides energy for active transport to take place when water potential is lower in the soil </li></ul></ul>
  11. 11. 5. Osmosis in the Root cells <ul><li>The soil particles have a higher water potential than the vacuole of the root hair cell. </li></ul><ul><li>Water and nitrates diffuse from the soil particles to the root hair cell. </li></ul><ul><li>The root hair cell becomes more dilute than the surrounding cortex cells. Water and nitrates diffuse from the root hair cell to the cortex cells by osmosis. </li></ul><ul><li>Water diffuses from one cell to another until water eventually enters the xylem tubes </li></ul><ul><li>Intake of water in the roots, the root hair cells become turgid. A pressure is thus generated. This pressure is called root pressure. This forces water up the xylem tissues. </li></ul>
  12. 12. 6. Forces causing water movement <ul><li>Root pressure </li></ul><ul><ul><li>Produced by the continuous movement of water through the root hair cells </li></ul></ul><ul><ul><li>Pushes water up the xylem </li></ul></ul><ul><li>Transpiration pull </li></ul><ul><ul><li>Produced by the evaporation of water from the leaves </li></ul></ul><ul><ul><li>Pulls water up the xylem </li></ul></ul><ul><li>Capillary action </li></ul><ul><ul><li>Produced by the conduction of water by the xylem through its continuous lumen </li></ul></ul><ul><ul><li>Pushes water up narrow xylem vessels </li></ul></ul>
  13. 13. 7. Transpiration in the stomata <ul><li>In the stem xylem, water is pulled up the stem by transpiration pull. </li></ul><ul><li>Osmosis continues through the leaf cells and water is eventually drawn in from the xylem vessels in the stem. </li></ul><ul><li>As the water evaporates, the water potential of cell sap decreases. It draws water from the lower cells by osmosis. </li></ul><ul><li>Water evaporates from the surfaces of leaf cells into air spaces. </li></ul><ul><li>Water vapour from the air spaces diffuses through the stoma and into the atmosphere. </li></ul>
  14. 14. 7. Transpiration pull of plants <ul><li>Plants absorb a large amount of water, but make use of only a small portion of the water. </li></ul><ul><li>A large portion of water is lost by evaporation of water through the stomata of the leaves. This process is called transpiration. </li></ul><ul><li>Transpiration is the loss of water vapour mainly from the stomata of the leaves. </li></ul><ul><li>As water evaporates from the leaves, more is drawn up through the plant to replace it due to cohesion forces between water molecules in the xylem tissues. </li></ul><ul><li>A pulling force called the transpiration pull is formed. </li></ul>
  15. 15. 7. Importance of Transpiration pull <ul><li>Transpiration pull is the transport of water and mineral salts or nitrate ions from the soil to the leaves. </li></ul><ul><li>Ensures a constant flow of water to be taken from the soil to the leaves. </li></ul><ul><li>Enables photosynthesis to occur. </li></ul>
  16. 16. 8. Rate of transpiration increase <ul><li>Humidity of air </li></ul><ul><ul><li>Low </li></ul></ul><ul><li>Dryness of air </li></ul><ul><ul><li>High </li></ul></ul><ul><li>Temperature of air </li></ul><ul><ul><li>High </li></ul></ul><ul><li>Speed of wind </li></ul><ul><ul><li>High </li></ul></ul><ul><li>Light intensity </li></ul><ul><ul><li>High </li></ul></ul>
  17. 17. 8. Light intensity <ul><li>Presence of light </li></ul><ul><ul><li>Photosynthesis occurs. </li></ul></ul><ul><ul><li>Cell sap in guard cells has higher concentration of glucose. </li></ul></ul><ul><ul><li>Water enters the guard cells by osmosis causing guard cells to become turgid. </li></ul></ul><ul><ul><li>Stomata opens and transpiration increases. </li></ul></ul><ul><li>Absence of light </li></ul><ul><ul><li>No photosynthesis occurs. </li></ul></ul><ul><ul><li>Plant loses water, guard cells flaccid. </li></ul></ul><ul><ul><li>Stomata closes and transpiration decreases. </li></ul></ul>