Construct a hypothesis to explain the observation

Experiment 1: Light dependent reactions

Table 1: Amount of air generated in each test tube

Test Tube 1 [Change in distance (mm)]

Test Tube 2 [Change in distance (mm)]


1. Which test tube had a bigger bubble on the top before the experiment?

After the experiment?

2. What do you hypothesize is causing the bubble at the top?

3. What role do you hypothesize the sodium bicarbonate played?

4. From what you know about plants, if we were to place one of the test tube and beaker combinations in front of a green light, what would happen?

Experiment 2: Depletion of carbon dioxide

Table 2: Color change over time

Time 0 min 15 min 30 min 45 min 60 min



1. What happened to the color of the solution over one hour?

2. What is the process that is occurring to make the phenol red solution change colors?

3. If we placed a green light in front of the test tube, do you think the results would be different? Why or why not?

AIDitional Questions:

1. Some plants (grasses) tend to contain a greater concentration of chlorophyll than others (pines).

Construct a hypothesis to explain this observation? Would it be testable?

2. Given what you now know about chloroplasts, pigments and wavelengths, consider trees whose leaves turn yellow in the fall.


What is happening in the leaves at the cellular and molecular levels?

3. We have seen that chloroplasts are the organelles in plant cells that provide energy to the cell. The equivalent organelle in eukaryotic (animal) cells is the mitochondria. Both are unusual in that they have double membranes and contain their own set of DNA.


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