Transport in Plants

• What do plants require to ensure all cells receive nutrients?

  A transport system
• How do xylem and phloem contribute to plant nutrition?

  Xylem transports water; phloem transports sugars
• What are the components and functions of the vascular bundle?

  • Components: Xylem and phloem
  • Functions:
  • Transport of substances
  • Structural support
• How are xylem vessels arranged in the vascular bundle?

  In an X shape
• What mechanical forces can the X shape of xylem vessels withstand?

  Various mechanical forces such as pulling
• What surrounds the X shape arrangement of xylem vessels?

  Endodermis
• What is the role of the endodermis in the vascular bundle?

  Supplies xylem vessels with water
• What is the inner layer of meristem cells in the vascular bundle called?

  Pericycle
• What is the arrangement of xylem and phloem in the stem of non-woody plants?

  • Xylem: Inside for support and flexibility
  • Phloem: Outside of the vascular bundle
  • Cambium: Layer between xylem and phloem
• How do vascular bundles function in leaves?

  • Form midrib and veins
  • Dicotyledonous leaves have a network of veins
  • Involved in transport and support
• What do xylem vessels transport?

  Water and minerals
• What structural feature allows xylem vessels to form a continuous column?

  Long cylinders made of dead tissue with open ends
• What are pits in xylem vessels used for?

  Allow sideways movement of water
• What substance thickens xylem vessels?

  Lignin
• In which direction can water flow in xylem vessels?

  Only upwards
• What are phloem vessels made of?

  Living cells
• What is the process called that involves the movement of nutrients in phloem?

  Translocation
• What do sieve tube elements transport?

  Sugars such as sucrose
• What are companion cells involved in?

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

  Through plasmodesmata
• What is the role of stomata in transpiration?

  Allow gas exchange and water vapor exit
• What is transpiration and its significance in plants?

  • Process of water absorption through roots
  • Water moves up and is released as vapor
  • Enables photosynthesis, growth, and temperature control
• What is osmosis in the context of transpiration?

  Water moves from xylem to mesophyll cells
• What happens during evaporation in transpiration?

  Water vapor exits from mesophyll cells
• How can the rate of transpiration be measured?

  Using a potometer
• What factors affect the rate of transpiration?

  • Number of leaves
  • Size/position of stomata
  • Presence of waxy cuticle
  • Light, temperature, humidity, air movement
  • Water availability
• What are xerophytes?

  Plants adapted to dry conditions
• How do xerophytes minimize water loss?

  Through adaptations like smaller leaves
• What role do hairs and pits play in xerophytes?

  Trap moist air to reduce water loss
• How do hydrophytes adapt to their aquatic environment?

  Thin or absent waxy cuticle
• What is the purpose of wide, flat leaves in hydrophytes?

  Provide large surface area for light absorption
• What is the function of air sacs in some hydrophytes?

  Keep leaves afloat
• How does water enter root hair cells?

  Through a water potential gradient
• What is the purpose of root hair cells?

  Provide large surface area for water movement
• How are minerals absorbed by root hair cells?

  Through active transport
• What is the Casparian strip?

  A layer of suberin in the endodermis
• What are the two pathways for water movement in roots?

  1. Symplast pathway: Through cytoplasm and plasmodesmata
  2. Apoplast pathway: Through cell wall spaces
• How does water cross the endodermis?

  By entering the symplast pathway
• What aids the upward movement of water in xylem vessels?

  Root pressure and cohesion
• What is the tension-cohesion theory?

  Describes water movement due to cohesion and tension