Lab - Carbon Fixation in Elodea

1. Why does the phenol red change color when we blow bubbles into the tube? Phenol red is an indicator in this experiment. What did it indicate?
The phenol red changes to a yellow color in the presence of CO2. The color change indicated whether or not the plant absorbed the CO2.

2. How long did it take to observe a color change in the phenol red? What does the color change indicate in terms of the Elodea plant?
It took about 30 minutes to see a color change, from yellow to red. This means the elodea plant absorbed the CO2.

3. If carbon fixation occurs during the light independent stage of photosynthesis, why did the procedure call for placement of the test tubes under grow lights?
CO2 + H2O -----light-----> glucose + O2
The plant needs light in order to absorb the CO2, and convert it to glucose and oxygen.

4. Did you see a change in color of the phenol red test tube with no elodea added? Why or why not?
No, because there was no plant absorbing the CO2 

5. Does carbon fixation occur in humans? Can you think of any other organisms that fix carbon?
No, carbon fixation occurs primarily in plants. 

6. How is does a plant use carbon? What is meant by the term “carbon fixation”? 
A plant uses carbon during photosynthesis. The plant uses carbon dioxide and water, in the presence of light, to make glucose and oxygen. Plants make there own food. Carbon fixation means that some living things, like plants, are able to break down carbon from CO2 to the carbon in organic compounds.

7. Identify and explain the control in this experiment. What is the purpose in having a control?
The tube without the plant was the control. Having a control is important to show change.

Before light..