Purpose: To demonstrate the production of oxygen and the utilization of carbon dioxide by plants in the course of photosynthesis.
Materials: Red cabbage juice or bromothymol blue, bottle with stopper and straw, spring of Elodea.
Procedure:
Place the solution of bromothymol blue or red cabbage juice into the bottle with the stopper and straw.
Exhale into the solution using a steady breathing rhythm until the blue color becomes yellow-green.
Remove the stopper and place a spring of Elodea in the solution.
Place the bottle in bright sunlight and observe the changes over a 2-3 day period.
Questions:
What were you blowing into the bottle?
Why do you think the solution changed color?
What do you predict will happen to the new colored water after the Elodea has been in the jar for a few days? Why?
What do you think would happen if at step #4, we placed the jar in a dark closet? Why? Let's try it.
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