1Into each bottle, pour 1 cup of warm water and 1 packet of yeast.
2In the 1st bottle do not add any sugar. To the 2nd one, add 1 teaspoon of sugar. To the 3rd one, add 4 teaspoons of sugar.
3Cap the bottles tightly and shake them all up for a few seconds.
4After shaking, take off the caps, put a balloon on each bottle, and observe them over 1 hour.
How It Works
In this demonstration, you will notice that the balloons fill up with gas. That gas is made by a type of fungus called yeast. Yeast is also a decomposer that breaks down large molecules like sugar into smaller molecules that can be reused in an ecosystem. One of the molecules that yeast produces is carbon dioxide, which collects in the balloons. The more sugar molecules we gave the yeast, the more carbon dioxide they made.
Check out the Full Lesson on Food Webs: Cycling of Matter & Flow of Energy!
In this lesson, we learn that:
Food is broken down and rearranged to form new molecules.
Food webs show us how matter cycles and energy flows in an ecosystems.
Food webs rely on the processes of photosynthesis and respiration.