Plant tissue and organs

• what is epidermal tissue 


  Consists of flattened cells

  Apart from guard cells lack chloroplast

  form a protective covering over leaves stems and roots

  Some have walls impregnated with a waxy substance forming a cuticle
• What is vascular tissue 


  Concerned with transport - xylem and phloem

  xylem- carry water and minerals from roots to all parts of the plant

  Phloem - sieve tubes transfer sucrose solution from leaves to parts of plants that don’t do photosynthesis
• What is meristematic tissue 


  Contain stem cells

  found at root and shoot tips and the cambium of vascular bundles - area called meristems

  • Divide by mitosis and differentiate
  • Thin walls - little cellulose
  • No chloroplast
  • Not a large vacuole
• What are the key steps in the formation of xylem from cambium cells?

  • Cambium cells differentiate into xylem vessels
  • Lignin is deposited in cell walls
  • Cell walls are reinforced and waterproofed
  • Cells die due to lignin deposition
  • Ends of cells break down to form continuous columns
  • Wide lumens are created for water and mineral transport
• How are phloem derive from meristems

  • Other cambium cells differentiate into phloem sieve tubes or companion cells
  • Sieve tubes lose most of their organelles and sieve plates develop between them
  • Companion cells retain their organelles and continue metabollic functions to provide ATP for active loading of sugars into sieve tubes
• What are the 4 plant organs

  Leaf - photosynthesis

  Root - anchorage in soil

  absorption of mineral ions and water

  storage

  Stem - support, hold leaves up so they are exposed to light

  transportation of minerals and water

  transports and storage of products for photosynthesis

  Flower - sexual reproduction