1. State the Problem: How much carbon dioxide does the plant Elodea absorb and how much oxygen does it release?
Why are two investigations needed to show gas exchange during photosynthesis?
Two investigations are needed to show gas exchange during photosynthesis because photosynthesis involves the absorption of carbon dioxide and the release of oxygen. In order to accurately measure the amount of carbon dioxide absorbed and the amount of oxygen released, separate investigations must be conducted.
How will we measure the amount of carbon dioxide that Elodea has absorbed?
The amount of carbon dioxide that Elodea has absorbed can be measured by using bromothymol blue (BTB) as an indicator. BTB turns yellow in the presence of carbon dioxide.
How will we measure the amount of oxygen Elodea has released?
The amount of oxygen Elodea has released can be measured by counting the number of oxygen bubbles produced by the plant.
2. Hypothesis
Independent Variable: Presence of light
IF the Elodea plant is exposed to light,
THEN it will absorb more carbon dioxide and release more oxygen.
Dependent Variable: Amount of carbon dioxide absorbed and amount of oxygen released.
3. Experiment
Control: BTB solution without Elodea
Materials: Elodea plant, BTB solution, baking soda, test tubes
Procedures:
1. Prepare a BTB solution by adding baking soda to the solution.
2. Pour the BTB solution into test tubes.
3. Place Elodea plants in some of the test tubes.
4. Place the test tubes with Elodea in a well-lit area and the test tubes without Elodea in a dark area.
5. Observe and record the color of the BTB solution in each test tube over a period of time.
6. Count the number of oxygen bubbles released by the Elodea plants at different time intervals.
4. The data expected to be collected in this investigation includes:
- The initial color of the BTB solution in each test tube.
- The color of the BTB solution after a certain period of time.
- The number of oxygen bubbles released by the Elodea plants at different time intervals.
A. How will you determine whether photosynthesis has occurred? What color does BTB make the water to begin with? What color do you expect the water to be IF photosynthesis has occurred?
To determine whether photosynthesis has occurred, we will observe the color of the BTB solution. BTB makes the water greenish-yellow to start with. If photosynthesis has occurred, we expect the water to remain greenish-yellow or turn green.
If an Elodea plant placed in the BTB + baking soda solution overnight is yellow in the morning, it means that photosynthesis has occurred. We think there would be oxygen bubbles present in this case.
The trial that performed photosynthesis when left in the light is Trial 2 (Baking Soda, BTB, and Elodea). The trial that performed photosynthesis when left in the dark is Trial 3 (Baking Soda, BTB, and Elodea).
The graph of the number of oxygen bubbles released per minute for 5 minutes will show the time in minutes on the horizontal axis and the number of bubbles on the vertical axis.
5. Conclusion:
The data supported the hypothesis that the presence of light would result in the absorption of more carbon dioxide and the release of more oxygen by the Elodea plant. In the investigation, the BTB solution remained greenish-yellow or turned green when photosynthesis occurred. The presence of oxygen bubbles also indicated the occurrence of photosynthesis.
To improve the experiment in the future, more trials could be conducted to increase the reliability of the results. Additionally, controlling factors such as temperature and light intensity could provide a more accurate understanding of the impact on photosynthesis.
Through this investigation, I learned that photosynthesis is a process in which plants absorb carbon dioxide and release oxygen. The presence of light is essential for photosynthesis to occur. The use of indicators such as BTB can help determine the occurrence of photosynthesis by detecting the presence of carbon dioxide. The release of oxygen bubbles serves as further evidence of photosynthesis.