Why should the addition of hydrogen carbonate increase the rate of bubbling in photosynthesis (elodea?)?

Question

Why should the addition of hydrogen carbonate increase the rate of bubbling in photosynthesis (elodea?)?

Answer 1

If you're in a high school biology class this lab is probably expecting you to say that bicarbonate increases the amount of available carbon dioxide.

If this is for a college level course that explanation is not sufficient, and research shows it may not be correct.  Bicarbonate itself might be necessary for the oxygen evolving(giving off) process of photosynehesis (http://www.plantphysiol.org/cgi/reprint/... ).  Also, bicarbonate in higher concentrations reduces the inhibitory effects of several anions that bind to the same site in photosystem II as bicarbonate (http://www.plantphysiol.org/cgi/content/... ).