Photosynthesis – counting oxygen bubbles in pondweed

Integrated ScienceLife ProcessesAges 12–13

A classic experiment: a sprig of pondweed (Elodea) sits in a beaker of water under an inverted funnel with a collecting test tube. In light, the plant photosynthesizes and releases oxygen as countable bubbles. Students drag the lamp closer or farther, or drag sliders for light, CO₂, and temperature, to see how the bubble rate changes; a graph of photosynthesis rate against the selected factor shows the current point and either a saturating curve (light, CO₂) or a curve with an optimum (temperature).