plant organisation

• Flower


  Reproductive part of plant
• Stem


  Supports the leaves and flowers
• Roots


  Absorb water and mineral ions
• Leaves


  Carry out photosynthesis
• Epidermal tissue


  Waxy substance to waterproof leaf surface
• Palisade tissue


  Contains lots of chloroplasts for photosynthesis
• Guard cells


  Control the opening and closing of the stomata
• Stomata


  Contains tiny pores that allow gases in
• Xylem


  Carries water and mineral ions from roots to leaves
• Phloem


  Carries glucose from leaves to plant
• Spongy mesophyll


  Has airspaces and a large surface area to make diffusion of gases easier
• Water is needed for photosynthesis and is carried by the xylem
• Carbon dioxide is needed for photosynthesis and is carried by the stomata
• Oxygen is needed for respiration and is transported to plant through diffusion
• Glucose is needed for respiration and is carried by the phloem
• How water moves from soil to roots:

  1. Water moves into root hair cells by osmosis
  2. Mineral ions enter the plant through the roots by active transport(transport energy is needed)
  3. Root hair cells can take in more water because they have an increased surface area
  4. Root hair cells can facilitate active transport because they have lots of mitochondria which release energy through respiration
• Xylem tissue

  • Made up of xylem cells which are hollow tubes strengthened by lignin
  • Being hollow allows water to travel uninterrupted from roots to leaves
  • Water evaporates through the stomata(transpiration stream)
• Phloem tissue

  • Composed of tubes of elongated cells with sieve tubes at each end
  • Glucose can move through one phloem cell to the next by pores in the end walls
• Movement of dissolved sugars

  Translocation
• Transpiration

  • Excess water is lost from the leaves through the stomata
  • Water evaporates from the cells lining the air spaces then passes out of the leaf(through the stomata)by diffusion
  • As water evaporates from the surface of the leaves more water is pulled up from the roots through the xylem to take its place
  • The constant movement of water through the xylem is called the transpiration stream
• Transpiration is measured by a potometer
• High temperatures mean faster transpiration as the leaf gains kinetic energy so the water evaporates faster and moves away from the leaf faster.Also causes low water concentation.
• Wind causes water molecules to move away from the leafs surface faster so its evaporation is quicker causing faster transpiration
• High humidity means that lots of water surrounds the leafs surface so there is less transpiration
• Increased light intensity means more photosynthesis is taking place to there is increased transpiration
• Meristem tissue is made up of plant stems cells. It's found in the growing parts of the plant such as the tips of shoots and roots.