Carol Hwang hwang at biodec.wustl.edu
Wed Oct 25 12:24:25 EST 1995

Were the values for the controls consistent between the 2 experiments?
If not, were the differences between acidic or basic and control levels 
greater that the difference between the 2 controls?
My vague recollection from 20 years ago is that measurements of O2 
evolution could be pretty variable.  I also recall that we so strongly 
illuminated the samples that we put our samples in a water-jacketed 
vessel but maybe you can get a response from someone with more recent 
experience.  Also, there is a school of thought that Chlamy are sensitive 
to Na+ and K+ should be used instead.
Teresa Dou (teresad at unixg.ubc.ca) wrote:
: 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

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