in plants

• Respiratory surfaces


  Parts of a living organism in which respiratory gases (oxygen and carbon dioxide) are exchanged between the atmosphere and cells (or blood)
• Respiratory surface


  The parts of living organisms across which respiratory gases can be exchanged between the environment (atmosphere) and the organism's cells
• Respiratory surfaces in animals


  • Large surface area
  • Thin (short diffusion distance)
  • Moist
  • Permeable
  • Good blood supply
  • Steep concentration (diffusion) gradients
• Respiratory surfaces in plants

  • Large surface area
  • Thin exchange surfaces
  • Moist and permeable walls
  • Diffusion gradient caused by respiration (and photosynthesis during the day) in cells, leading to the diffusing gases being in lower or higher concentrations than in the intercellular air spaces
• Plants do not have an active breathing system to further increase concentration gradients or a blood system to carry diffusing gases to and from the gas exchange surfaces
• Gas exchange in plants

  • Takes place across the cell membranes
  • Large surface area from spongy mesophyll and stomata
  • Thin cell membranes allow rapid diffusion/gas exchange
  • Permeable cell membranes allow gases to cross
  • Gases diffuse quickly to maintain the concentration gradient
• More oxygen is used in respiration during exercise, so breathing increases to supply more oxygen and remove more carbon dioxide