Question: What effect does water temperature have on the rate of photosynthesis in Elodea?
Plants are ideographic organisms that engage in the process of photosynthesis. In the process of photosynthesis, an organism creates ATP and organic molecules, using sunlight as their energy source(1). Various environmental factors may influence the rate at which plants may produce organic molecules. Examples of such environmental factors include light intensity, temperature, and distance from a light source(1).
Elodea condensers, also known as American water weed, is a common, aquatic plant in North American lake ecosystems. It provides both food and habitat for many aquatic life forms. Elodea can grow in a wide range of conditions, including various depths of water and in various sediment types (2). In addition to its ecological importance, Elodea is commonly sold as an aquarium plant.
In this experiment, the rate of photosynthesis was measured in Elodea plants subjected to various temperatures of water.
1. Johnson, George B. 1998. Visualizing Life. Holt, Reinhard, Winston. 243-245.
2. Native Freshwater Plants. Washington State Department of Ecology. 2003.
Hypothesis: The rate of photosynthesis will increase with increasing temperatures of water.
Independent Variable: Temperature of the water
Dependent Variable: Number of bubbles produced per minute
3 100mL test tubes
8 250 ml beakers
2400 ml refrigerated pond water
3 Elodea sprigs
* Pour 300mL of chilled pond water into each of eight beakers.
* Using a hotplate, heat one beaker to 16 CO.
* Pour 100mL of the heated water into a 100mL test tube.
* Place one sprig of Elodea into each test tube, with the cut stem pointing up.
* Place the test tube 30cm from a light source.
* Count the number of bubbles released from the stem over the course of one minute.