cpac 10

    Cards (13)

    • Photosynthetic pigments
      Chlorophyll alpha, chlorophyll beta, carotene etc.
    • Wavelengths of light
      Different wavelengths are absorbed by photosynthetic pigments
    • More light absorbed

      Increases rate of photosynthesis
    • Light not absorbed
      Will be reflected
    • Filters
      Block out certain wavelengths (and therefore colours) of light from reaching the chloroplast
    • Filters blocking wavelengths
      Affects rate of photosynthesis
    • Measuring rate of photosynthesis
      By measuring volume of gas produced (assumed to be oxygen)
    • Equipment
      • Pondweed
      • Beaker
      • Sodium hydrogencarbonate
      • Aluminum foil
      • Spatula
      • Light filters (pieces of coloured cellophane)
      • Photosynthometer
      • Paperclip
      • Bench lamp
      • Ruler
      • Thermometer
      • Stop clock
    • Method
      1. Place pondweed in beaker of water
      2. Cover one side with aluminium foil to block out light
      3. Cover other side with light filter
      4. Add sodium hydrogencarbonate to provide carbon dioxide
      5. Leave for 5 minutes
      6. Place bench lamp at set distance
      7. Set up photosynthometer and leave for 5 minutes
      8. Record volume of gas produced
    • Biohazard - Use disinfectant, wash hands with soap after handling
    • Lamps - Do not look directly at lamp, wait for afterimage to disappear
    • Sodium hydrogencarbonate - Wear eye protection, avoid contact with skin
    • Graph
      Plot a bar graph of colour of filter against volume of gas produced
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