2) Place the boiling tube 30 cm from a bench lamp. [Optional- measure the light intensity].
3) Wait two minutes.
4) Count the number of bubbles rising from the cut end during the next five minutes.
5) Record your results in an orderly fashion (table).
6) Repeat steps 2-5 but with the tube at 60 cm., then 90 cm., and finally 120 cm. from the light.
7) Plot your results on the squared paper provided.
8) If you have time, you may repeat the experiment, but with different distances.
2) Does the distance between the lamp and the plant affect the rate of bubble production? Is there a straightforward relationship?
3) What other factor might have affected the rate of photosynthesis?
4) How could the experiment be improved?
5) Why was sodium hydrogencarbonate used?
6) What were the bubbles made of?
>Oxygen
How would you prove it?
>Glowing splint test (if you can get enough!)
7) How can extra experimental readings be made which are most significant? Would these require any special procedure?
8) Do you think that these results apply to ordinary land plants? Give reasons.
9) What is the advantage of Canadian pondweed in a fishtank? Does it need any special treatment?
