Transpiration and translocation

• How do root hair cells absorb water from the soil

  Osmosis
• How do root hair cells absorb mineral ions

  Active transport
• Role of xylem

  Transports water and mineral ions from roots to the stems and leaves
• What is the xylem tissue made of

  Hollow tubes of dead cells strengthened by lignin
• Flow of water molecules that pass through the xylem

  Transpiration stream
• In which directions can water move through the xylem


  Up the plant through the xylem
• Role of phloem tissue

  Transports dissolves sugars and amino acids (cell sap) from the leave to the rest of the plant for use
• What is the phloem tissue made of

  Made up of elongated cells which form long tubes
• Flow of cell sap through the phloem

  Translocation
• Which direction can cell sap move through the phloem

  Either up or down the phloem
• Transpiration meaning

  Evaporation of water from the leaves of plants
• 4 factors that affect the rate of transpiration

  Temperature

  Light intensity

  Humidity

  Wind speed
• How does temperature affect the rate of transpiration

  Increases with temperature

  High temp —> higher energy particles —> more likely to evaporate and diffuse out the stomata
• How light intensity affects the rate of transpiration

  Increases with light intensity

  High light intensity —> more photosynthesis —> stomata open more (to let co2 in) —> more water can diffuse out
• How does wind speed affect the rate of transpiration

  Increases with wind speed

  The windier it is the more quickly evaporated water will blow away from the area around the stomata

  Means there will be a stronger concentration gradient for water vapour to diffuse out the leaf

  So water vapour will diffuse out more quickly
• How humidity affect the rate of transpiration

  Decreases as humidity increases

  Higher the humidity the more water vapour there is

  Decreasing the concentration gradient

  The lower the concentration gradient the slower water vapour will diffuse