Plants

• Guard cells control the opening and closing of stomata by changing shape.
• Stomata are small openings on the underside of leaves, which allow gases to enter or leave the leaf.
• Similar to the insect gas exchange system, all living cells are close to a source of oxygen and carbon dioxide
• Like in insects, plants diffusion takes place in the gas phase, which makes it more rapid than if it were in water
• Stomata a minute pores that occur mainly on the leaves. Each stoma is surrounded by a pair of guard cells
• Stomata:

  A) Thin outer wall

  B) Thick inner wall

  C) Stomata aperture

  
• Leaf structure:

  A) Upper epidermis

  B) Mesophyll cells

  C) Lower epidermis

  D) Stomatal pore

  E) Guard cell