This project idea comes to you from Science AL!VE in Burnaby, British Columbia. | ![]() |
If a drink that's being carbonated is placed in a sealed container, the space between the liquid and the cap fills up with carbon dioxide. As the concentration of carbon dioxide increases, the gas starts to get pushed into solution and the bubbles stay in the water. This makes the drink carbonated. If the cap was loose, the gas would escape and you would get "flat" pop. As long as the yeast have enough sugar to eat, they keep making carbon dioxide. When the yeast run out of sugar, they start another metabolic process called fermentation. This process produces alcohol as a waste product. This is why yeast are used to produce the alcohol found in beer. We refrigerate our ginger beer so that the yeast don't multiply so much that they run out of food, and thus produce alcohol instead of carbon dioxide.
Yeasts are a type of fungus. They are unicellular organisms, meaning that the whole organism is made up of only one cell. These organisms are not at all complex, and they have no systems. Multicellular organisms, on the other hand, are much more complex. Often they have groups of cells that work together to perform a specific task. For example, your organs are just large groups of cells that form tissues, and those tissues together form an organ. Of course, when scientists are studying things like metabolism, it is much easier to study it in an organism as simple as a unicellular organism. Yeasts are very often used for studies in the lab because of their simplicity.
The world is full of unicellular organisms. A few examples are amoeba, paramecia, bacteria, etc.
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