Eugleeena

A. Introduction

Phototaxis is the movement of an organism towards or away from a light source. In this experiment the phototaxis of the live specimen, Euglena will be observed. The purpose is to find whether the Euglena will present negative or positive phototaxis when exposed to a beam of light after being subjected to darkness. Would the chloroplasts in the Euglena have an effect on the specimen's phototaxis and overall nature or movement? By observing the phototaxis it is possible to better understand the nature and location in which Euglena would be likely found. The hypothesis was that Euglena will present positive phototaxis when exposed to a light source.

B. Methods and Materials

This experiment used a standard light microscope, a slide with a cover slip, a live sample of Euglena, gum Arabic, and a pen light. I prepared the specimen by placing a drop of pond water with live Euglena on to a slide and then placed a drop of gum Arabic on that in order to slow the specimens down for better observation. The slide was then covered with a cover slip and placed onto the microscope. The Euglena was then observed using a low power objective. The lights in the room were turned off and the blinds were drawn. A penlight was pointed on side of the slide and the phototaxis of the Euglena was observed. The specimen was left to sit in the darkness for 10 seconds. This process was done three times. The penlight was then positioned to another side of the slide and then same three trial process was repeated for all four sides of the slide. Negative phototaxis was indicated by placing a - sign in the box and positive phototaxis was indicted by placing a + sign in the box. The entire class data was then pooled.

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