transpiration and the stomata

• 1. Transpiration ​is the loss of water of water vapour from the leaves and stems of the plant.
• • Water also evaporates at the open ​stomata ​(pores) on the leaf surfaces
  • ●  As water molecules are attracted to each other, when some molecules leave theplant the rest are pulled up through the xylem
  • ●  This results in more water being taken up from the soil resulting in a continuoustranspiration stream​ through the plant
• Guard cells ​close and open stomata.

  • ●  They are kidney shaped
  • ●  They have thin outer walls and thick inner walls
  • ●  When lots of water is available to the plant, the cells fill and change shape, openingstomata (they are also light sensitive)
  • ●  This allows gases to be exchanged and more water to leave the plant via evaporation
  • ●  More stomata are found on the bottom of the leaf, allowing gases to be exchangedwhilst minimising water loss by evaporation as the lower surface is shaded and cooler.
• Guard cells​ - Cells that surround the stomata and change shape depending on the volume of water. They control the rate of transpiration by becoming turgid or flaccid, opening or closing the stomata.
• Phloem ​- A transport tissue found in plants that is specialised to transport sugars from the leaves to the rest of the plant in both directions.
• Stomata ​- Small holes found on the surface of a plant that can be opened or closed by guard cells to control water loss and gas exchange
• Xylem ​- A transport tissue in plants that is specialised to transport water and dissolved

  minerals from the roots of the plant to the leaves.