transpiration

• absorption of water:

  1. minerals are taken into root hair cell by active transport (low to high -> needs ATP ) , so water concentration decreases
  2. this causes water to move into root hair cell by osmosis (high to low)
  3. root hair cell now has higher water concentration than the cell next to it, so water moves from the root hair cell to the next by Osmosis.
  4. water then enters the xylem
• uses of glucose =

  • cellulose for cell walls
  • oils
  • stored as starch
  • protein
  • sucrose
• transpiration = the loss of water vapour through the stomata by evaporation
• transpiration:

  1. water enters plant from the root hair cells
  2. osmosis occurs at the roots when water moves from high concentration in soil to lower concentration in the root
  3. water enters xylem by osmosis
  4. water moves up stem and into leaf
  5. water is lost from the leaves by evaporation through the stomata pores by transpiration
  6. water is moved up xylem from the root to the leaf.
• water transport in xylem = unidirectional (one-way) from root to leaves
• rate of transpiration is affected by humidity, air movement and light intensity
• temperature increase -> transpiration increase (more kinetic energy)
• light intensity increase -> transpiration increase

  (when sunnier , stomata open wider to allow more co2 for photosynthesis -> more water can evaporate from leaves by stomata pores -> more transpiration)
• humidity increase -> transpiration decrease ( concentration gradient is not as steep so slower)
• air speed (wind) increase -> transpiration increase