Plant cell structure

• 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 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
• Leaf structure


  • Upper epidermis
  • Palisade mesophyll
  • Spongy mesophyll
  • Lower epidermis with stomata
• Stomata open


  Allows carbon dioxide diffusion but increases water loss
• Stomata closed


  Reduces water loss but limits carbon dioxide intake
• Guard cells


  Control opening and closing of stomata based on water status
• Most stomata are on underside of leaves to reduce water evaporation
• Meristem tissue


  Plant form of stem cells, found at growing tips, can differentiate into many cell types