Gas exchange in plants

• What are the key structures involved in gas exchange in a plant:

  • Mesophyll layers (palisade & spongy mesophyll)
  • Stomata - created by the guard cells
• How does gas exchange in plants work?

  • The palisade mesophyll is the site of photosynthesis, where lots of oxygen is produced and carbon dioxide is used up.
  • This creates a concentration gradient.
  • Therefore, oxygen will travel through the air spaces in the spongy mesophyll and diffuse out of the stomata (pores) created by guard cells
  • Carbon dioxide will diffuse in through the stomata.
• What are Xerophytic plants?

  Xerophytic plants are adapted to survive in environments with limited water.
• How are Xerophytic plants adapted to reduce water loss?

  • They have curled leaves to tap moisture to increase local humidity
  • They have hairs to trap moisture to increase local humidity
  • They have sunken stomata to trap moisture to increase local humidity
  • They have a thicker cuticle to reduce evaporation
  • They have a longer root network to reach more water
• Similarities between how xerophytic plants and terrestrial insects are adapted to reduce water loss.

  Complete the blank spaces.

  A) waterproof exoskeleton made of chitin reduces H2O loss

  B) Stomata can open and close to reduce water loss

  C) Some have shrunken spiracles to trap humid air

  D) Tiny hairs around spiracles reduce water loss

  E) Rolled or reduced leaves help enclose stomata

  
• How does gas exchange occur in plants?

  In plants, oxygen will travel through the air spaces in the spongy mesophyll and diffuse out of the stomata (pores) created by guard cells. Carbon dioxide will diffuse in through the stomata.