blood transport systems and transpiration

• What are the two types of transport vessels in plants?

  Xylem and phloem
• What is the primary function of phloem tubes?

  • Transport food substances (mainly sugars)
  • Move both up and down the stem
  • Known as translocation
• What are phloem tubes made of?

  Columns of living cells called sieve tube elements
• Why do sieve tube elements need companion cells?

  Because sieve tube elements have no nucleus and can't survive on their own
• What do phloem vessels primarily transport?

  Food substances, mainly sugars
• What is the main function of xylem tubes?

  • Carry water and minerals from the roots
  • Transport them up the shoot to the leaves
  • Part of the transpiration stream
• What are xylem tubes made of?

  Dead cells joined end to end with a lumen down the middle
• What material strengthens the cell walls of xylem tubes?

  Lignin
• What is transpiration?

  The loss of water from the plant
• Where does most transpiration occur in a plant?

  At the leaves
• How does transpiration create a shortage of water in the leaf?

  By evaporation and diffusion of water from the leaf's surface
• What is the transpiration stream?

  A constant flow of water drawn up from the roots to the leaves
• What are the benefits of the transpiration stream for plants?

  • Keeps the plant cool
  • Provides water for photosynthesis
  • Creates turgor pressure for support
  • Brings in minerals from the soil
• Why do leaves have stomata?

  To allow gas exchange for photosynthesis
• How does light intensity affect transpiration rate?

  Brighter light increases the transpiration rate
• How does temperature influence transpiration?

  Higher temperatures increase the rate of transpiration
• What happens to transpiration in windy conditions?

  It increases due to lower concentration of water vapor outside the leaf
• What adaptations do plants have to reduce water loss?

  • Waxy cuticle on upper epidermis
  • Stomata located on the lower surface of leaves
  • Smaller and fewer stomata in hot climates
• How do guard cells control the opening and closing of stomata?

  By becoming turgid or flaccid
• What shape do guard cells have?

  Kidney shape
• When do stomata typically open and close?

  Open during the day and close at night
• What is the purpose of a potometer in studying transpiration?

  • Estimates transpiration rate
  • Measures the distance moved by an air bubble
  • Helps understand environmental effects on transpiration
• What is the first step in using a potometer?

  Cut a shoot underwater to prevent air from entering the xylem
• How do you calculate the transpiration rate using a potometer?

  Divide the distance moved by the air bubble by the time taken
• If a bubble moved 25 mm in 10 minutes, what is the transpiration rate?

  $2.5 \text{ mm per minute}$
• How can environmental conditions affect transpiration rates?

  • Light intensity: More light increases transpiration
  • Temperature: Higher temperatures increase transpiration
  • Air movement: More air movement increases transpiration