2.5 biology

• Upper epidermis


  Upper layer of a leaf
• Palisade mesophyll


  • Cells that contain many chloroplasts for photosynthesis
• Spongy mesophyll


  • Cells that contain air spaces for gas exchange in the leaf for photosynthesis
• Xylem


  Carries water and minerals from the root to the leaf. Cells are dead and contain lignin
• Phloem


  Carries sugar up and down the plant. Cells are alive and contain sieve plates and companion cells
• Lower epidermis


  Lower layer of the leaf
• Guard cells


  • Cells that open and close stomata
• Stomata


  Pores on the underside of a leaf that allow gases to move in and out of the plant and water to exit by transpiration
• Transpiration


  Movement of water out of the stomata
• Plant transport organs


  • Leaves
  • Stem
  • Roots
• Epidermis


  Protective outer layer
• Xylem


  Transports water
• Phloem


  Transports Glucose (Sugar)
• Palisade mesophyll


  • Contain lots of chloroplasts for photosynthesis
• Spongy Mesophyll


  • Loosely arranged for gas exchange
• Moist air space


  Moist to allow gases to dissolve
• Stomata


  Allows Carbon Dioxide in and Oxygen out of leaf
• Guard cells


  • Open and close stomata
• Water movement


  1. Moves into the root hair cells by osmosis

  2. Moves up the stem and into the leaves through the xylem

  3. Exits through the stomata in the leaves
• Potometer


  Apparatus used to measure the transpiration rate of a plant
• Transpiration rate increases


  Increase in temperature, increase in wind speed, increase in surface area and a decrease in humidity
• Transpiration rate decreases


  Decrease in temperature, decrease in wind speed, decrease in surface area and increase in humidity