pondweed exp

• gas syringe for the oxygen to measure
• Set up a boiling tube

  1. Add 45 cm³ of sodium hydrogencarbonate solution (1%)

  2. Allow the tube to stand for a few minutes

  3. Shake to disperse any air bubbles
• Cut a piece of the pondweed, Cabomba

  The pondweed should be 8 cm long
• Place the pondweed in the boiling tube

  1. Use forceps to place it carefully

  2. Cut end uppermost

  3. Don't damage the pondweed or cause the liquid to overflow
• Position the boiling tube

  1. The pondweed should be 10 cm away from the light source

  2. Allow the boiling tube to stand for five minutes
• Count the number of bubbles

  1. Emerging from the cut end of the stems in one minute

  2. Repeat the count five times

  3. Record the results
• Calculate the average number of bubbles

  Produced per minute
• Repeat the experiment

  At different distances away from the light source