RP6 - the effect of light intensity on photosynthesis

• What apparatus is used in this practical activity?

  A boiling tube and a light source
• How do aquatic plants indicate photosynthesis?

  By producing visible bubbles of oxygen gas
• How does light intensity affect photosynthesis?

  Closer light increases light intensity
• What is the method for investigating light intensity's effect on photosynthesis?

  1. Set up boiling tube 10 cm from light source
  2. Fill with sodium hydrogen carbonate solution
  3. Insert pondweed with cut end up
  4. Wait 5 minutes
  5. Count bubbles produced in one minute
  6. Record results in a table
  7. Repeat for mean calculation
  8. Move to 20 cm and repeat
  9. Continue for 30 cm and 40 cm
• What is the concentration of the sodium hydrogen carbonate solution used?

  0.2%
• What should you do after placing the pondweed in the boiling tube?

  Leave it for 5 minutes
• What factors affect the rate of photosynthesis?

  • Light intensity
  • Light wavelength
  • Carbon dioxide concentration
  • Temperature
• What type of plant is used in this experiment?

  Pondweed
• What is the significance of using a freshly cut piece of pondweed?

  To ensure it is actively photosynthesizing
• Why is sodium hydrogen carbonate used in the experiment?

  To provide carbon dioxide for photosynthesis