Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Elodea, O2 and CO2
Name: Celeste B.
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 12/10/2002


Question:
Does the amount of Carbon dioxide present have an effect on the amount of oxygen plants (such as Elodea) produce? I am doing an experiment in which I am trying to answer this question, but my results are a bit strange... the Elodea (plantlike protist) placed in the water with the largest amount of baking soda (representing CO2) is not producing as much oxygen as the one with 2 tsp baking soda *half the amount. Is there a reason why 2 tsp. increased the oxygen produced and 4 tsp. did not increase it as much? Keep in mind that I made sure the following variables stayed constant: temp. and amount/intensity of light.


Replies:
Yes, the amount of CO2 available will affect O2 production:

http://www.agron.iastate.edu/~weeds/Ag517/2000/Unit3/u3limit.html

http://bio.winona.msus.edu/berg/241f99/Labs/Photosy.htm

Anthony Brach, Ph.D


There is another variable you have not accounted for: the pH. Bicarbonate is not exactly the same thing as CO2. Perhaps the Elodea photosynthesizes best within a certain pH range, and adding too much sodium bicarbonate to the medium raises the pH too high.

Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois



Click here to return to the Botany Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory