Transpiration

• what happens to most of the water intaken by the plant?

  transpires
• what occurs during transpiration? (in terms of guard cells and stomata)


  the guard cells become turgid when water enters, therefore opening the stomata, this allows for gas exchange, until enough water has left the guard cell, which then becomes flaccid, closing the stomata
• transpiration


  Evaporation of water from the leaves of a plant
• what happens if transpiration happens too fast?


  the plant will wilt
• what does the transpiration stream do? (5)


  -maintains cell turgidity

  -supplies cells with water

  -help keep plant cool

  -carry diss. mineral ions to leaves

  -photosynthesis
• factors affecting the rate of transp. (4 main ones)


  air movement

  temp

  humidity

  light
• factors affectiong the rate of transp. (the 4 non main ones) - still important


  thicness of cuticle

  no. leaves

  water availability

  no. stomata
• how does air movement affect transp.


  decreases water vapour in air, mainting a high concentration gradient - meaning transpiration happens faster
• how does humidity affect transp.


  more humid air decreases rate of transp. as there is lower concentration gradient
• how does temperature effect transpiration?


  water particles have more kinetic energy, so they can evaporate faster. also air can hold more water vapour
• how does light intesnity affect transpiration?


  stomata close in the dark, decreasing transpiration
• what does the plant need freshwater for?

  • Photosynthesis
  • support plant
  • keep plants cool
  • carry dissolved mineral ions