10.1.4 Leaf Structure

• Leaf


  Absorbs light energy for photosynthesis
• Leaf structure

  • Waxy cuticle (reduces water loss, thicker on upper surface)
  • Epidermis (1 cell thick, no chloroplasts)
  • Palisade mesophyll layer (most photosynthesis occurs, cells packed tightly, full of chloroplasts)
  • Spongy mesophyll (loosely packed with air spaces for gas diffusion)
• Vascular bundles


  Found in the upper and lower epidermis
• Stomata


  Pores in the lower epidermis with guard cells that change shape to open and close the stomata
• Function of stomata


  Allow carbon dioxide to enter the leaf for photosynthesis, allow oxygen and water vapour to leave via diffusion
• When stomata close


  To prevent water loss
• Adaptations of leaves for photosynthesis


  • Waxy cuticle
  • Thin epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Stomata

  
• When drawing cross sections through leaves, we draw tissues rather than individual cells