Mass transport in plants

• Transpiration -> the process by which water evaporates from the leaves of plants into the atmosphere
• Potomers are the piece of equipment in which measure the rate of transpiration
• Plants respire ALL the time
• Anaerobic respiration :

  
  

  Lactic acid -> glucose
• aerobic respiration :

  
  

  oxygen + glucose -> carbon dioxide + water
• The leaf is made up of 5 components :

  
  

  > upper epidermis

  > palisade mesophyll

  > spongy mesophyll

  > lower epidermis

  > stomata

  
  

  umbrella’s probably soak less sideways
• Upper epidermis ->

  
  

  single layer , transparent
• palisade mesophyll ->

  
  

  where photosynthesis occurs (lots of chloroplast)
• Chloroplast has the ability to move themselves in a position to give maximum light absorption
• Spongy mesophyll ->

  
  

  site of gas exchange
• Spongy mesophyll adaptations ;

  moist surface , large surface area , large number of air space.
• lower epidermis ->

  large number of stomata , diffusion of gases in and water vapour out
• stomata -> tiny pore surrounded by guard cells
• [opening stomata]

  • Guard cells take in water through osmosis
  • become turgid
• [closing stomata]

  • guard cells loose water
  • Become flaccid
• Factors affecting the open/close stomata :

  • Light
  • CO2
  • Water
• Light -> increased light intensity means more photosynthesis so stomata opens
• CO2-> accumulates the cell , causes stomata to close
• Water -> lack of closes the stomata
• Lenticels -> small areas of bark where cells are loose , allows oxygen and CO2 to diffuse in and out
• xerophytes ->species of plant that has adaptations to survive in an environment with little liquid water
• An example of a xerophyte is cacti
• xerophytes are adapted to consume water during dry periods
• 5 ways in which plants are adapted to reduce water loss ;

  • thick cuticle
  • Rolling up of leaves
  • Hairy leaves
  • stomata in pits or grooves
  • reduced SA:V of leaves
• Thick cuticle -> a waxy layer, a waterproof barrier , less water escapes
• Rolling up of leaves-> leaf rolls into itself , traps moist air, becomes saturated with water vopour
• Hairy leaves -> at lower epidermis , traps moist air , reduces water potential gradient
• Stomata in pits or grooves -> trap moist air , reduces water potential gradient
• Reduced Sa;V of leaves -> reduction in SA is balanced against the need for a sufficient area of photosynthesis