ATS GCSE Biology - Plant tissues

• flaccid


  cell lacking waterstoma closed to preserve waterplant possibly wilting

  
• turgid

  cell full of water

  
• stomata


  lots of stoma
• closed stoma

  reduces evaporation of watertranspiration reduced

  
• open stoma

  for gas exchange & photosynthesisoxygen outwater outcarbon dioxide in

  
• stoma


  tiny openings formed from two guard cellscontrols water loss and gas exchange

  
• guard cells flaccid

  water moves out of cellsstoma closed no gas exchangereduces water loss from leaves

  
• guard cells turgid

  stoma open for gas exchangecells full of water

  
• guard cells


  surround a stoma

  
• meristem


  plant stem cells growing areas of plants

  
• phloem


  carries dissolved sugars around plant sugar made from photosynthesis, transported to growing areas of stems and rootssugars used to make new plant cellssugars also sent for storage (as Starch, fats and oils)two directional flow of sugar in phloemliving tissue (found in a ring just under the bark)(Think FLOW-EM - flowing both directions)

  
• xylem


  carries water and dissolved mineral ionsfrom roots to stems & leavesone way only mature xylem are DEAD = bulk of wood

  
• spongy mesophyll tissue

  big air spaces & large surface area easier diffusion of gases oxygen & water vapour out carbon dioxide into leafcontains some chloroplasts for photosynthesis

  
• palisade mesophyll tissue


  contains lots of chloroplasts for photosynthesis

  
• epidermal tissues


  make epidermiscover surfaces & protect themoften secrete a waxy substance that waterproofs the surface of the leaf

  
• leaf


  plant organ made up ofepidermis palisade mesophyll spongy mesophyll xylemphloemguard cells

  
• plant tissues

  epidermal palisade mesophyllspongy mesophyll xylemphloemmeristem