Plant tissues, organs and systems

• How is epidermal tissue adapted for its function

  epidermal tissue covers the entire plant. It has a waxy cuticle which helps reduce water loss from the leaf
• How is palisade mesophyll tissue adapted for its function

  Palisade mesophyll tissue contains lost of chloroplasts which allows photosynthesis to progress at a rapid rate
• How is sponge mesophyll tissue adapted for its function

  Spongy mesophyll tissue has lots of air spaces which allow gases(including oxygen and carbon dioxide)to diffuse in and out
• How is the xylem adapted for its function

  • Made up of dead cells which form a continuous hollow tube-allows the movement of water and mineral ions from the roots to the leaves
  • strengthened by lignin -makes the vessel strong and water proof
  • has bordered pits-allow minerals to be transported to specific places
• How is the phloem adapted for its function

  • Made up of Enron gated living cells
  • cells have sieve plates that connect the together- cell Sao can move through plates into other cells
  • sieve tube cells have few organelles to allow the efficient transport of substances
• How is meristem tissue adapted for its function

  Made up of stem cells which can differentiate into may different cell types allowing the plant to grow
• What tissue does the leaf organ contain

  • Epidermis
  • palisade mesophyll
  • Spongy mesophyll
  • xylem
  • phloem
  • guard cells
• What’s the function of guard cells

  They control the opening and closing of the stomata according to the water content of the plant
• How are stomata adapted for their function

  Stomata allows the control of gaseous exchange and water loss from leaf

  • more stomata on the base of the leaf -minimises water loss as this side is cooler and shaded
  • have guard cells which control their opening and closing
• How are root hair cells adapted for their function

  Root hair cells allow the uptake of water and mineral ions from the soil

  • large surface area-maximises rate of absorption
  • contain lots of mitochondria-release energy for active transport of mineral ions
• What is translocation

  It’s the movement of dissolved sugars from the leaves to other parts of the plant
• What is transpiration

  It’s the evaporation of water vapour from the surface of a plant
• How does transpiration work

  • Water evaporates from the leaf surface via the stomata
  • water molecules cohere together -more water is pulled up the xylem in an unbroken Column
  • More water is taken up from the soil creating a continuous transpiration stream
• How does temperature affect the rate of transpiration

  Increasing the temperature increases the rate of transpiration .higher rate of evaporation and diffusion of water therefore rate of transpiration is increased
• how does humidity affect the rate of transpiration

  Increasing relative humidity decreases the rate of transpiration

  • high relative humidity will reduce the water vapour concentration gradient. The rate of evaporation will decrease and so will the rate of transpiration
• How does wind speed affect the rate of transpiration

  Increasing wind speed/air movement increases the rate of transpiration

  • increased air movement lowers water vapour concentration outside of the leaf. This increases the water vapour concentration gradient thereby increasing the rate of evaporation and transpiration
• How does light intensity affect the rate of transpiration

  Increasing the light intensity increases the rate of transpiration

  • the rate of photosynthesis increases so more stomata open. This allows the rate of evaporation to increase, increasing the rate of transpiration