plant cell organisation

• Levels of organization in plants

  • Cells
  • Tissues
  • Organs
  • Organ systems
• Leaf


  An organ that, along with a stem and roots, forms an organ system for the transport of substances around the plant
• Photosynthesis


  1. Requires carbon dioxide and water

  2. Water transported from soil by roots and xylem

  3. Carbon dioxide diffuses into leaf through stomata

  4. Photosynthesis occurs in palisade mesophyll layer
• Stomata


  • Tiny holes in the lower epidermis of the leaf
  • Allow carbon dioxide to diffuse into the leaf
  • Controlled by guard cells to balance carbon dioxide intake and water loss
• Palisade mesophyll


  • Layer where most photosynthesis occurs
  • Packed with chloroplasts
• Xylem and phloem


  • Transport water and nutrients around the plant
• Cuticle


  • Waxy waterproof layer on top of leaf to reduce water loss
• Guard cells are turgid


  Stomata open wider
• Guard cells are flaccid


  Stomata close
• Meristem tissue


  • Plant stem cells found at growing tips
  • Can differentiate into many cell types to allow plant growth
• Most stomata are on the underside of leaves to reduce water evaporation