1. State the Problem
How much carbon dioxide does the plant Elodea absorb, and how much oxygen does it release?
To understand the process of photosynthesis in aquatic plants like Elodea, we need to investigate their gas exchange capabilities.
Why are two investigations needed to show gas exchange during photosynthesis?
Two investigations are needed to demonstrate gas exchange during photosynthesis because one experiment can focus on measuring the uptake of carbon dioxide (CO2) while the other can measure the production of oxygen (O2). This dual approach ensures that both aspects of the gas exchange process are accurately represented and allows for a better understanding of the overall photosynthetic activity.
How will we measure the amount of carbon dioxide that Elodea has absorbed?
We can measure the amount of carbon dioxide that Elodea absorbs by using a water-based solution of a pH indicator (such as bromothymol blue) that changes color in response to changes in CO2 concentration. As Elodea absorbs CO2 during photosynthesis, the pH of the solution will rise, indicating a decrease in CO2 levels.
How will we measure the amount of oxygen Elodea has released?
To measure the amount of oxygen released by Elodea, we can use a gas collection method, such as capturing the O2 produced in an inverted graduated cylinder or test tube placed over the plant. Another approach is to use a dissolved oxygen meter to record the changes in oxygen levels in the surrounding water over a set time period.
2. Hypothesis
Independent Variable: The amount of light exposure (intensity or duration)
Hypothesis Statement: IF the amount of light exposure is increased,
THEN the rate of carbon dioxide absorption by Elodea will increase,
AND consequently, the rate of oxygen released by Elodea will also increase.
Dependent Variable: The rate of carbon dioxide absorption and oxygen production
This structured hypothesis highlights the relationship between light exposure (independent variable) and the resulting effects on gas exchange in the Elodea plant (dependent variables).
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