Transpiration and translocation

• What are the two types of vessels in flowering plants for transporting substances?

  Xylem and phloem
• How do xylem and phloem vessels differ in their function?


  Xylem transports water and minerals, while phloem transports food substances
• What is the structure of phloem tubes?


  • Made of columns of elongated living cells
  • Small pores in the end walls for cell sap flow
• What substances do phloem tubes primarily transport?


  They transport food substances, mainly dissolved sugars
• In which directions do phloem tubes transport substances?


  In both directions
• What is the process called when phloem transports food substances?


  This process is called translocation
• What is the structure of xylem tubes?


  • Made of dead cells joined end to end
  • No end walls between them
  • Strengthened with lignin
• What do xylem tubes carry from the roots to the rest of the plant?


  They carry water and mineral ions
• What is the term for the movement of water from the roots through the xylem?


  This movement is called the transpiration stream
• What do xylem vessels carry compared to phloem vessels?


  Xylem vessels carry water, while phloem vessels carry sugars
• How can you remember the difference between phloem and xylem?


  Phloem transports substances in both directions, while xylem only transports upwards
• What happens to a house plant if it is not watered for a few days?

  It starts to go droopy
• What is transpiration?


  Transpiration is the loss of water from the plant
• What causes transpiration in plants?


  It is caused by the evaporation and diffusion of water from a plant's surface
• Where does most transpiration occur in the plant?


  Most transpiration happens at the leaf
• What happens when water evaporates from the leaf during transpiration?


  A slight shortage of water is created in the leaf, drawing more water up from the roots
• What is the result of the constant transpiration stream in plants?


  There is a continuous movement of water through the plant
• How do leaves facilitate transpiration while allowing gas exchange?


  Leaves have stomata that allow gases to be exchanged easily
• How much water does a big tree lose from its leaves daily?

  About a thousand litres
• Why do roots need to be effective at drawing in water from the soil?


  Because a big tree loses a significant amount of water daily
• What factors affect the rate of transpiration?


  • Temperature
  • Humidity
  • Wind speed
  • Light intensity