transpiration and translocation

• what is a xylem?

  plant tissue that contains long tubes that carry water and dissolved minerals from the roots to the leaves
• features of xylem:

  • very thick walls containing ligmin - supports plant
  • cell walls sealed with lignin causes the xylem cells to die
  • the end walls between the cells break down= form long tubes so H20 and dissolved minerals can flow easily
• what things dont xylem cells not have?

  nucleus cytoplasm vacuole chloroplasts = easier for water and minerals to flow
• do xylem cells transport substances 1 way or both ways?

  1 way
• what are phloem cells?

  Plant cells responsible for transporting dissolved sugars up and down the plant.
• what are the structures of phloem vessels cells?

  1. have no nucleus and only limited cytoplasm = same reason
  2. end walls have pores called sieve plates = allow dissolved sugars to move through the inside of cell
  3. they don't have much of mitochondria
  4. has companion cells connected by the pores - contains mito to provide energy to the phloem
• which plant tissue cell transports water and minerals?

  xylem
• which plant tissue cells transports dissolved sugars?

  phloem
• which plant tissue cell transports substances both ways?

  phloem
• what are transpiration cells?


   move water from the roots to their leaves in xylem vessels
• what are translocation cells?

  Phloem cells.
• what is the palisade mesophyll?


  where the photosynthesis takes place
• how does the water enter the roots?

  through the root hair cells
• what is transpiration?


  water is constantly evaporating from the surfaces of leaves
• how does the transpiration stream occur?

  1. the evaporation of water from cells inside the leaf
  2. the WV diffuses through the air spaces in the spongy mesophyll and out of the leaf through the stomata
  3. water passes from the xylem Into the leaf to replace the water that has been lost
  4. water is drawn into the root hair cells and up the xylem vessels to the leaf
• what dissolved mineral ions does transpiration stream transport?

  magnesium
• what is Mg used for in plants?

  Chlorophyll
• what is nitrate ions used for in plants?

  for growth
• how does the leaf cool down?

  by the evaporation of water from the leaf in warm water
• factors that affect the rate of transpiration?

  Humidity, temperature, wind speed, light intensity,
• how does humidity affect the rate of transpiration?

  transpiration is faster because evaporation takes place more quickly under dry conditions
• how does temperature affect the rate of transpiration?

  faster - evaporation is faster
• how does wind speed affect the rate of transpiration?

  Increases - wind removes any wv allowing more water to evaporate
• how does light intensity affect the rate of transpiration?

  directly proportion - high light intensity increases in the rate of photosynthesis allowing the stomata to open and allow CO2 to enter
• how does stomata work in transpiration?

  • stomata are surrounded by 2 guard cells
  • when light intensity is high the guard cells swell and they change their shape = stomata opens
  • CO2 can diffuse into the leaf and be used in photosynthesis
  • in hot conditions the plants close its stomata to reduce water loss by transpiration
  • plant cannot photosynthesis