Posted by: Nick Voss | October 18, 2013

Environmental Science: Beholding Mitochondria in Plant Cells

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ENVIRONMENTAL SCIENCE LAB– Recently, Conserve School students carried out a lab that examined how aquatic plants affect dissolved oxygen in water. Although the study was confined to small test tubes inside the lab, the experiment connects directly to ecological processes just outside the lab. This science activity provided the foundation for an in-depth class discussion on ecosystem health, water conservation, and human interaction with the environment. Come to think of it, entire careers are devoted to the content covered in this lab!

So in one test tube, we have a few ounces of water. In the other, we have water with a small piece of Java moss. In each test tube, we insert a few drops of bromothymol blue. This chemical would indicate the presence of oxygen in the water by looking, well, blue. Carbon dioxide in the water however, would be indicated by the same chemical turning yellow. So in terms of the test tube with Java moss, would the plant have more or less dissolved oxygen than the one with just water? The answer, students discovered, lay in the moss’ plant cells. Andy Milbauer, Conserve School Environmental Science teacher, explained that plant cells possess mitochondria, which helps them engage in cellular respiration. Just as humans breathe, plants take in and give out oxygen. As a result, aquatic plants such as Java moss decrease the dissolved oxygen in the water. In the end, the test tube with water that remained blue was the one without plants.

The findings of this lab set up a larger discussion about what is happening just outside here in Land O’ Lakes, Wisconsin, and all over the world. The level of aquatic plants determines the oxygen levels in water, which in turn determines the potential for all other aquatic life in that water body, such as invertebrates and fish. Students discussed how the human influence on water bodies sometimes increases the level of nutrients in the water. With more nutrients coming in from erosion or fertilizers, the water body sees a spike in aquatic plant life. If the number of aquatic plants is too high, then the potential for other aquatic life may decrease, leading to fish kills and the degradation of the entire aquatic ecosystem. Herein lies the question: how do humans balance their needs for water resources with the needs of a healthy aquatic ecosystem?

This lab provided students with an introduction to a fundamental and critical issue in environmental science: the stewardship of water resources. Students who continue to take life science courses will find that they will encounter this complex topic frequently. Some Conserve School alums have decided to major in this area in college, and who knows, perhaps someday a Conserve School student might even pursue a career related to the conservation of water resources!

-Nick Voss, Academic Coordinator Grad Fellow


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