BackgroundWhen we (humans) breath, we use oxygen and give off carbon dioxide in a process called respiration. Plants, trees and algae use carbon dioxide and give off oxygen in a process called photosynthesis. These two cycles create what is known as an interdependent relationship; plants rely on animals for carbon dioxide and animals rely on plants for oxygen. In a closed environment such as the space shuttle, humans use oxygen at a rate that is difficult to replace with plants alone given limited space.
ObjectiveThis purpose of this science demonstration is to observe photosynthesis in action using the freshwater plant Elodea and compute how much Elodea it would take to generate enough oxygen for one human breath. Photosynthesis converts carbon dioxide, water and energy (in the form of light) to sugar, water and oxygen. The chemical equation looks like this:
MethodIn the Scott Carpenter Station experiment hood, you will see a jar wrapped in aluminum foil labeled "Photosynthesis demonstration". This jar contains Elodea underneath an inverted funnel with a graduated test tube (marked for volume measurement) over the narrow end of the funnel. As the Elodea photosynthesizes, it gives off oxygen that is captured in the funnel and rises into the test tube. This allows us to measure the amount of oxygen generated by the Elodea.
QuestionsIs the amount of Elodea required practical to use on a space station?
What other ways can you think of to provide O2 and remove CO2 from an enclosed environment?
Measurement Collection Sheet