Systems

• Plants need air, water and food to survive
• How plants get water and food


  How they transport them from one part to another
• How water from the soil reaches the top of trees


  What happens to the food made by the leaves
• Why plants have a transport system


  Various parts of the plant get food and water through the transport system such as roots, stem, leaves
• Parts of the plant transport system

  • Food carrying tubes
  • Water carrying tubes
• Functions of the plant transport system

  1. Food carrying tubes transport food from leaves to all parts of the plant

  2. Water carrying tubes transport water and minerals from roots to all parts of the plant
• A simplified diagram represents the food carrying and water carrying tubes in a plant
• Minerals dissolved in soil water are taken up by root hair cells and transported throughout the plant via the phloem.
• Water is absorbed through the roots into xylem vessels, where it travels up to the leaves.
• Plant cells are surrounded by cell walls, which prevent them from bursting when water enters the cell.
• Water moves through the xylem by cohesion-tension theory, where water molecules stick together due to hydrogen bonds.
• Xylem vessels have thick walls made up of lignin, which provides strength and support.
• Xylem is composed of non-living cells, while phloem is made up of living cells.
• The xylem vessels are dead cells that transport water from the roots to the leaves.
• Phloem is in charge of transporting sugars produced during photosynthesis from the leaves to other parts of the plant.
• Xylem is responsible for transporting water and minerals from the roots to the rest of the plant.
• The transpiration stream creates tension within the xylem, pulling water upwards against gravity.
• Phloem carries sugars produced during photosynthesis from the leaves to other parts of the plant.
• Sieve tube elements have no nucleus or endoplasmic reticulum, but contain mitochondria and plastids.
• Sucrose is loaded into the sieve tube elements (STEs) in the source tissue (leaves).
• Parenchyma cells store food reserves such as starch and oil.
• Translocation occurs when sucrose molecules move downstream along the sieve tubes in the phloem.
• Translocation occurs when sugar is loaded into sieve tubes at source tissues (leaves) and unloaded at sink tissues (roots).
• Stomata are small openings on the underside of the leaf that allow gases such as oxygen and carbon dioxide to enter and exit the leaf.
• Water moves through the xylem by cohesion and adhesion, with negative pressure created at the top of the stem due to evaporation.
• Companion cells are small, oval-shaped cells located next to sieve tubes.
• Xylem vessels transport water and dissolved mineral salts upwards from the root system to other parts of the plant.
• Phloem loading involves the transfer of sugars from mesophyll cells to companion cells via plasmodesmata.
• The end walls of companion cells contain plasmodesmata that connect them to adjacent parenchyma cells.
• The end walls of companion cells contain plasmodesmata that connect them to adjacent parenchyma cells.
• Water enters the plant through roots and moves upwards by transpiration pull.
• Root hair cells have an extensive surface area to absorb water and minerals.
• Root hair cells have an extensive surface area to absorb water and minerals.
• Water enters the plant through roots and moves upwards by transpiration pull.
• The end walls of companion cells contain plasmodesmata that connect them to adjacent parenchyma cells.
• Root hair cells have an extensive surface area to absorb water and minerals.
• Water enters the plant through roots and moves upwards by transpiration pull.
• Sieve plates have pores between adjacent companion cells that connect them to neighboring sieve tube elements.
• Sieve plates have pores between adjacent companion cells that connect them to neighboring sieve tube elements.
• Sieve plates have pores between adjacent elements allowing movement of substances across them.