Photosynthesis

• What is the aim of the experiment described?

  Investigate light intensity's effect on photosynthesis
• How is the rate of photosynthesis measured in this experiment?

  By observing color change in bicarbonate solution
• What aquatic organism is used in the experiment?

  Pondweed
• What does the bicarbonate indicator solution change color with?

  Increasing concentrations of CO2
• What equipment is needed for the experiment?

  • Boiling tube
  • Algal beads
  • Light source
  • Ruler
  • Test tube rack
  • Stopwatch
  • Glass rod
  • Measuring cylinder
  • Bicarbonate indicator solution
  • Bicarbonate indicator colour standard chart
• How far should the boiling tube be placed from the light source initially?

  10 cm
• What should be done after placing the algal beads in the boiling tube?

  Fill the boiling tube with bicarbonate indicator
• What should be recorded at the start of the experiment?

  Initial colour and pH of the solution
• How long should the experiment run before recording the final results?

  30 minutes
• What should be done after recording the final colour and pH?

  Repeat for 3 more distances
• What is plotted on the graph after the experiment?

  Rate of photosynthesis against light intensity
• What formula is used to calculate light intensity in this experiment?

  Light intensity = 1/distance$^2$
• What are the controlled variables in the experiment?

  • Temperature
  • Amount of carbon dioxide
  • Volume of indicator solution
• Why is temperature controlled in the experiment?

  To ensure it doesn't affect photosynthesis rate
• What is a potential source of error in judging the solution's color?

  Difficulty matching to the color standard chart
• What are the potential hazards in the experiment?

  • Boiling water risk
  • Allergy risk from algae
  • Hot lamp
  • Electrical hazards
• What should be done to avoid electrical hazards?

  Keep water away from electrical outlets