Duckweed Lab Report 3p5572

Marilyn Deaner Due 11/28/12 Section 008

Introduction Duckweed is an aquatic plant used often in removing some nitrates from water. In this lab we will be testing how it grows in different environments. Our group has selected to look at how light affects the growth. Our hypothesis is that the duckweed left in natural light for a week will yield more frond growth than those left in high or low light.

Abstract: In this lab we wanted to see how different levels of light affected the growth of Duckweed. To do so, we had 2 samples placed in carrying levels of light. We used natural light which was near the window, high light on a rack with constant light on it, and for low light we put the samples in a drawer. * There could be a confounding variable with the sampled placed in the drawer because they could be exposed to less oxygen* Methods: We gathered six cups and filled each cup halfway with distilled water. We then counted out twenty-five duckweed frons and put that amount in each cup. After that we placed plastic wrap over each of the cups and poked ten holes in the plastic wrap. We labeled all six cups, two cups for each light source we used (high light, natural light, low light). Finally, we placed two cups in each of the light sources. The

high light cups were placed under a high light, the normal light cups were placed by a window, and the low light cups were placed in a drawer. Results All cups placed in the environment began with 25 fronds. After a week had ed the results were as follows: Natural light: 45 and 47 High light: 43 and 43 Low light: 27 and 27

Duckweed Frond Growth in Varying Light High light after High light initial Low Light after Series2 Low light Initial

Sample 1

Natural Light After Natural Light initial 0

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Conclusion Before we conducted our experiment, we hypothesized that the natural light environment would be the best place for fond growth. After observing the cups from: natural light, high light, as well as low light environments, we conclude that the amount of fronds ed our hypothesis. Although there was only a small margin of increase between the natural light and high light, both fond amounts in those environments dominated the amounts of fronds in the low light. The small

growth in the low light environment could have been due to lack of oxygen rather than the lower levels of light. If the experiment were to be repeated, the low light environment should be one with a more consistent availability of oxygen t the other samples.