Plant Transport Systems

• What do plants need water for?

  Photosynthesis, chemical reactions, and to keep cells turgid
• What do plants need sugars for?

  Respiration and to build organic molecules
• Why can't most plants obtain substances by simple diffusion?

  Because they are multicellular and have a large surface area: volume ratio
• What do plants have instead of simple diffusion for transport?

  Mass transport systems
• What do xylem vessels transport?

  Water and dissolved mineral ions
• What are vascular bundles in plants?

  • Grouping of xylem and phloem vessels
  • Found within the plant stem
  • Provide transport and support
• What do phloem vessels transport?

  Dissolved substances such as sucrose and amino acids
• What is the function of sclerenchyma fibres?

  To provide support to the stem
• What is parenchyma in plants?

  A type of simple permanent tissue that makes up ground tissues
• Where is the vascular bundle found in the center of the root?

  In the central core of xylem
• What is the arrangement of phloem in the root?

  Phloem is found between the arms of the xylem
• What provides strength to the roots?

  The structure of the vascular bundle
• Where is the vascular bundle located in the stem?

  Near the outer edge of the stem
• What is the position of xylem and phloem in the stem's vascular bundle?

  Xylem is towards the inside and phloem is towards the outside
• What is cambium in plants?

  A layer of meristem cells that can divide to produce xylem or phloem
• What do vascular bundles form in leaves?

  The mid-rib and veins of the leaf
• How do the veins in leaves change as they spread from the midrib?

  They get smaller as they spread out
• What is the primary function of xylem?

  To transport water and minerals from roots to leaves
• What does xylem tissue consist of?

  Tubes, fibres, and living parenchyma cells
• What is a key feature of xylem in dicotyledonous plants?

  Long cells with thick walls impregnated with lignin
• How does xylem transport water and minerals?

  Through a pipeline of dead cells arranged end to end
• What happens to xylem cells as they mature?

  Lignin waterproofs the walls, causing cell death
• What provides support for the plant in xylem structure?

  Thick cell walls of dead cells
• How do xylem tissues carry water to the top of the plant?

  By being made from dead cells aligned end-to-end
• What role do pits in lignified walls play in xylem function?

  They allow water to move sideways between vessels
• What is the significance of lignin in xylem walls?

  It allows stretching as the plant grows
• What are phloem vessels made of?

  Living cells
• What is translocation in plants?

  The movement of nutrients to storage organs and growing parts
• What do sieve tube elements do in phloem vessels?

  They form a tube to transport sugars in sap
• What is the role of companion cells in phloem?

  Involved in ATP production for active processes
• How are companion cells and sieve tube elements connected?

  Through plasmodesmata, allowing communication and flow of substances
• What is the structure of a cross-section of a root?

  • Central core of xylem
  • Phloem located between the arms of xylem
  • Provides strength to withstand pulling forces