Plant structures and their functions

• formula for photosynthesis

  carbon dioxide + water → glucose + oxygen
• factors affecting the rate of photosynthesis

  • light intensity
  • temperature
• root hair cells

  large surface area for absorbing water and mineral ions
• phloem tubes

  • elongated living cells
  • transports sucrose to the rest of the plant
  • translocation (requires energy from respiration)
• xylem tubes

  • dead cells with no end walls
  • strengthened by lignin
  • carry water and mineral ions from roots to stem and leaves
  • transpiration (movement of water from roots through xylem)
• transpiration

  • movement of water through the xylem
  • water enters the roots via osmosis through the cell membrane, but also diffuses through the cell wall
• factors affecting transpiration

  • temperature: increased temp means faster photosynthesis and more evaporation
  • windspeed: increased wind speed means increased evaporation, and faster transpiration
  • humidity: high humidity means slow evaporation which means slower transpiration
  • light intensity: high light intensity means faster photosynthesis, and faster transpiration