3.3:LEAVES

• Stomata


  Openings on the leaf surface that allow gas exchange
• Main function of leaves


  1. Photosynthesis

  2. Absorb water

  3. Transport water and nutrients

  4. Gas exchange
• Monocot leaf


  • Narrow leaves
  • Parallel veins running through the whole length of leaf
  • Stomata on both upper and lower epidermis
• Dicot leaf


  • Broad leaves
  • Central vein (midrib) with branching network (reticulate venation) of veins towards the outer edges
  • Stomata confined to the lower epidermis
• Movement of water and minerals in plants

  1. Absorbed by root hairs

  2. Travels up the stem

  3. Transported through xylem vessels in leaf veins

  4. Enters mesophyll cells
• Movement of organic compounds in plants

  1. Produced in mesophyll cells during photosynthesis

  2. Transported through phloem vessels in leaf veins

  3. Travels to other parts of the plant
• Gas exchange in leaves

  1. Gases enter and leave through stomata by diffusion

  2. Water vapour diffuses out through stomata (transpiration)