Plant tissues, organs and systems

• What are tissues in a plant?


  • Epidermal
  • Palisade mesophyll
  • Spongy mesophyll
  • Xylem
  • Phloem
  • Meristem
• What's epidermal tissue?


  • A waxy cuticle
  • Reduces water loss by evaporation
• What's palisade mesophyll tissue?

  • Lots of chloroplasts for photosynthesis
  • Top of the leaf so they receive the most light
• What's spongy mesophyll tissue?


  • Lots of air spaces
  • Allows gases to diffuse in and out of cells
• What's xylem tissue?


  • Found in roots, stems, and leaves
  • Made of hollow dead cells to create a tube
  • Lignin strengthens the cell wall
  • Function is the transpiration stream (moves water and minerals)
• What's phloem tissue?


  • Found in roots, stems, and leaves
  • Elongated cells with sieve plates at the end
  • Responsible for translocation (bidirectional)
• What's meristem tissue?


  • Found at the tips of roots and shoots
  • Able to differentiate into different types of plant cells
  • Allows plant to grow
• What's translocation?


  The movement of food substances (dissolved sugars) up and down the phloem
• What's transpiration?


  Loss of water vapour from leaves
• What are guard cells?

  • Open and close stomata
  • Kidney shaped
  • Thin outer walls and thick inner walls
  • Become turgid when filled with water, stomata open
  • Become flaccid when there's a lack of water, stomata close
  • Found on the bottom of the leaf to minimise water loss by evaporation