Classwork 104
Do Plants Pass Gas? (Part 1)
Aim: How does the wavelength of light affect photosynthesis?
Introduction
Our upcoming experiment is going to investigate how factors in the environment can affect how plants are able to produce and consume gases. We will be working with Elodeaplants which grow in freshwater and are often used in aquariums. Photosynthesis is an important reaction, both to plants and the animals that depend on them.
As discussed, photosynthesis uses carbon dioxide, light and water to produce oxygen and glucose. The easiest chemical to measure in this case is carbon dioxide. We can again use the indicator BTB (bromthymol blue) to detect and measure if carbon dioxide is being removed from the water (and being used for photosynthesis). Carbon dioxide causes the normally blue BTB to turn green and then yellow (if enough CO2 is present).
The removal of carbon dioxide should cause the BTB to return to its blue color. A bluer color is the result of the presence of less carbon dioxide. Less carbon dioxide is the result of it being used as a reactant in photosynthesis. A yellow color would mean that more carbon dioxide was produced (and that photosynthesis probably did not occur. Think about what reaction would create more carbon dioxide and a yellow color in the BTB).
What reaction would cause BTB to turn yellow? ______________________________________________________
What reaction would cause BTB to turn blue? _____________________________________________________
Elodea can be kept in a sealed tube with water and BTB in order to show how photosynthesis and respiration change the amounts of CO2 in a solution.
Your group will develop a question to investigate and a hypothesis to test in order to answer that question. The question should focus on how photosynthesis is affected by the color of light (ex. red, green, blue, yellow, or white).
After you develop your question, you and your group will develop hypotheses to test. Make sure that your hypotheses are clear, specific and measurable. For example, how would you measure that something is going to cause the plant to do more or less photosynthesis?
Make sure you have a testable questionthat is
- answered through an experiment, not research - practical
- asked with a “How?” instead of “Why?” - specific
Write your experimental question in the space below.Make sure you have a testable hypothesis (or hypotheses) that is
- measurable - specific
- clear
Write your hypothesis or hypotheses in the space below.Classwork 105
Saving the Forest for the Trees
Aim: To determine causes of and problems associated with deforestation.
Procedure
Read one (or both) of the two selections about deforestation and answer the following questions. This assignment will be collected.
1. In 5-10 sentences summarize the problem being described in the article. Think about and include these aspects of the issue:
a. what is happening
b. where in particular it is happening
c. when it happened/is happening
d. why it is happening
2. Identify the stakeholders (people who care about any aspect of the problem) and describe their views on the problem/its causes.
3. Describe any solutions being proposed.
4. Which solution do you think is best? If you feel it is necessary, then you can design a realistic solution of your own.
5. How might each of the stakeholders described in #3 feel about the solution you decided upon in #4? Support your answers with sound reasoning.
Resources for Classwork 105
Deforestation Overview
National Geographic "Eye in the Sky"
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