I have performed an experiment on the Chlamydomonas by providing them
different pH levels of medium. The First one is around pH 5 (use dilute
sulfuric acid + Chlamy. medium); the second one is around pH 9.5 (use
diluted sodium hydroxide + Chlamy. medium); the third is the control with
a pH of about 6.5). Then, I added in 3 mL of the solution to 3 mL of
Chlamydomonas. They are exposed to an equal amount of light (with
the exact distance from the light source and w/ same voltage light bulbs)
for 40 minutes. We measured the pH level and the oxygen level before
and after the experiment. It is noticed that the oxygen level has
increased for all of them. However, the basic one produced more O2 than
the control and the acidic one produced less O2 than the control. A week
before, I performed the same experiment with the same procedures (except
this time, I approx the distance between the light and the Chlamy. and
also the pH of the acidic soln is about 5.45), the results are the exact
opposite. Is the light source the only explanation for the contradicting
results? Can you suggest other reasons that may explain for this strange
results? ARe the Chlamy. capable to tolerate an acidic environment (like
acid rain) better or a basic one( like the commercial use detergents)? Why?
Are there any books, articles that deal with this particular topic?
Thank you very much for your help!
Teresa
