transport

• Plants have a transport system to carry nutrients within them
• Water from the soil is needed by the stem and leaves
• The nutrients that leaves make during photosynthesis are needed by other regions of the plant like stems and roots
• Xylem


  Transport vessel that transports water and mineral ions from the roots to the stem and leaves, also provides structural support to the plant
• Phloem


  Transport vessel that transports food (sucrose and amino acids) made by the plant from photosynthesizing leaves to non-photosynthesizing regions in the roots and stem
• Xylem vessels have no cell contents, cells are joined end to end with no cross walls, and the walls are thickened with lignin
• These structural adaptations allow the xylem to form an uninterrupted tube through which water can pass easily
• Xylem and phloem vessels are collectively called vascular bundles
• Vascular bundles are found throughout the root, stem and leaves
• Position of xylem and phloem in cross sections

  • In roots, xylem is in the centre, phloem is surrounding it
  • In stems, xylem is in the inner part, phloem is in the outer part
  • In leaves, xylem is in the upper part, phloem is in the lower part
• Root hair cells


  Specialized cells in roots that are adapted to absorb water and minerals from the soil
• Adaptations of root hair cells

  • Greatly increased surface area
  • Increases rate of absorption of water by osmosis
  • Increases rate of absorption of mineral ions by active transport
• Pathway of water uptake

  1. Enters root hair cells from soil by osmosis

  2. Passes into root cortex cells

  3. Travels into xylem

  4. Travels up stem to leaves

  5. Enters mesophyll cells
• Staining experiment to observe water pathway

  • Place celery in water with red or blue dye
  • Observe colour changes in celery stalk and leaves
• Transpiration


  Loss of water vapor from leaves
• Transpiration process


  1. Water from soil travels through roots to xylem and up to leaves

  2. Water evaporates from mesophyll cell surfaces into air spaces

  3. Water vapor diffuses out of leaves through stomata
• Transpiration


  • Related to large internal surface area of mesophyll cells
  • Related to size and number of stomata
• Cohesion


  Forces of attraction between water molecules
• Transpiration pull


  Each water molecule in xylem pulls the one below it as water evaporates at leaf
• Water does not travel through xylem by osmosis as xylem cells do not have living contents or cell membranes
• Potometer


  Apparatus used to measure transpiration rate
• Potometer experiment


  1. Air bubble introduced into capillary tubing

  2. Tap opened to push bubble back to zero

  3. Time measured as bubble travels along scale

  4. Repeated with different conditions
• Faster bubble movement


  Greater rate of water uptake and transpiration
• Factors affecting transpiration rate

  • Temperature
  • Wind speed
  • Humidity
• Increased temperature


  Increased transpiration rate
• Increased wind speed


  Increased transpiration rate
• Increased humidity


  Decreased transpiration rate
• Wilting


  Occurs when water loss from leaves exceeds water uptake from soil, causing plant to become soft and droop
• Translocation


  Transport of sucrose and amino acids in phloem from sources (where produced) to sinks (where used or stored)
• Sources


  • Parts of plant that release sucrose or amino acids
• Sinks


  • Parts of plant that use or store sucrose or amino acids
• During winter


  Phloem transports sucrose and amino acids from storage organs to other parts for respiration
• During spring


  Storage organs are sources, growing areas are sinks
• During summer


  Leaves are sources, roots are sinks storing sucrose as starch
• Circulatory system


  The primary method used to transport nutrients and gases through the body in most animals
• Fish circulatory system


  • Single circulatory system
  • Heart has two chambers: atrium and ventricle
  • Blood passes through the heart only once to complete a full circuit
• Fish circulatory system


  1. Deoxygenated blood from body capillaries moves through atrium and ventricle

  2. Blood reaches gill capillaries where oxygen is absorbed

  3. Oxygenated blood moves from gill capillaries to body capillaries completing one circuit
• Gill circulation


  When the heart pumps blood to the gills to be oxygenated
• Systemic circulation


  When the oxygenated blood continues through the rest of the body before arriving back at the atrium
• Mammalian circulatory system


  • Double circulatory system
  • Heart has four chambers
  • Blood passes through the heart twice for every one circuit of the body