How to show that algae emit carbon dioxide in the light?

With the help of observations and experiments, it is possible to show the release of oxygen by algae in the light.
1. You can observe for some time the appearance of gas bubbles on the leaves of Elodea.
2. You can collect gas bubbles in a test tube and check for the presence of oxygen gas using a glowing splinter, if a splinter flares up, then there is oxygen

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