We can also demonstrate that the bubbles only form in the presence of strong light, by moving the experiment into the dark and making further observations. While we cannot prove in this experiment that the bubbles are oxygen without a gas probe, we can demonstrate, by use of a control, that the bubbles only form when the leaves are submerged in a sodium bicarbonate solution (which releases CO 2) and not when they are submerged in pure water. The light-independent reaction or Calvin Cycle takes carbon dioxide and fixes it in three-carbon molecules which will eventually be synthesized into glucose.Įxperiment: We will conduct a simple experiment using spinach leaves to demonstrate that, in the presence of light and carbon dioxide, leaf tissues produce gas bubbles.The light reaction is used to convert sunlight into chemical energy stored in ATP and another energy storage molecule called NADP.The energy accumulated in Stage 1 is used to drive Stage 2. Stage 2 can work in the light or in the dark. Oxygen molecules are colored to show their fate. The basic reaction is:Ħ C O 2 + 12 H 2 O + e -> 2 C 6H 12 O 6 + 6 O 2Ĭarbon dioxide + water + light energy -> glucose + oxygen Organisms that can make their own food are called autotrophs, and are at the base of the food chain. With water, light energy from the sun, and carbon dioxide from the air, photosynthetic organisms are able to build simple sugars.
Photosynthesis is one of the most important anabolic chemical reactions that allows life to exist on Earth.