Rate of photosynthesis

• 1.

  Place a test tube rack containing a boiling tube 10 cm away from the light source measure with ruler
• 2.

  Fill the tube with a fixed volume of sodium hydrogen carbonate solution
• 3.

  Place cut pondweed into the boiling tube with the cut end at the top gently push with a glass rod
• 4.

  Leave boiling tube to rest for 5 minutes
• 5.

  Start the stopwatch and count the amount of bubbles produced in one minute
• 6.

  For each light intensity repeat the count twice and take a mean
• 7.

  Record in a table
• 8.

  Repeat at different distances
• 9.


  Plot a graph of rate against light intensity Using light intensity = 1/dx²