plant structures and their functions

• Photosynthesis


  1. Carbon dioxide + water

  2. Light

  3. Glucose + oxygen
• Plants are Able to Make Their Own Food by Photosynthesis
• Photosynthetic organisms


  Green plants and algae
• Biomass


  The mass of living material
• Photosynthetic organisms are the main producers of food for nearly all life on Earth
• Chloroplasts


  Contain chlorophyll which absorbs light
• Photosynthesis


  1. Energy transfer to chloroplasts by light

  2. Carbon dioxide + water

  3. Glucose + oxygen
• Photosynthesis is an endothermic reaction - energy is taken in during the reaction
• Factors affecting rate of photosynthesis

  • Light intensity
  • Concentration of CO2
  • Temperature
• Any of the three factors can become the limiting factor
• Investigating effect of light intensity on rate of photosynthesis


  1. Set up apparatus

  2. Measure oxygen production over time

  3. Repeat with different light intensities
• Variables that should be controlled in the experiment are temperature and CO2 concentration
• Biomass


  The mass of living material in a plant
• Photosynthesis contributes to a plant's biomass
• Limiting factors of photosynthesis

  • Light intensity
  • CO2 concentration
  • Temperature
• Light intensity increases


  Rate of photosynthesis increases proportionally up to a point
• CO2 concentration increases


  Rate of photosynthesis increases up to a point
• Temperature increases


  Rate of photosynthesis increases up to an optimal temperature
• Beyond the optimal temperature, further increases in temperature will decrease the rate of photosynthesis
• Transpiration


  The loss of water from a plant's surface, mainly through the leaves
• Stomata


  Pores on the surface of leaves that allow gas exchange
• Guard cells


  Cells that surround the stomata and control their opening and closing
• Transpiration rate


  Affected by light intensity, temperature, and air flow around the plant
• Using a potometer to estimate transpiration rate


  1. Set up apparatus

  2. Measure bubble movement over time

  3. Calculate transpiration rate