Student Exploration: Photosynthesis Lab
Vocabulary : carbon dioxide, chlorophyll, glucose, limiting factor, nanometer, photosynthesis, wavelength Prior Knowledge Questions (Do these BEFORE using the Gizmo .)
To survive, what gas do we need to breathe in?
Where is this gas produced?
Gizmo Warm-up During photosynthesis , plants use the energy of light to produce glucose (C 6 H 12 O 6 ) from carbon dioxide (CO 2 ), and water (H 2 O). Glucose is a simple sugar that plants use for energy and as a building block for larger molecules.
A by-product of photosynthesis is oxygen. Plants use some of the oxygen they produce, but most of it is released. In the Photosynthesis Lab Gizmo™, you can monitor the rate of photosynthesis by measuring oxygen production
1. Observe the left pane closely. What do you think the bubbles are?
2. Select the BAR CHART tab. On the graph, notice the Oxygen production bar. Move the Light intensity slider back and forth. How does light intensity affect oxygen production?
3. Experiment with the vertical Temperature slider (upper left) and the CO 2 level slider. A. How does temperature affect oxygen production?
B. How does CO 2 level affect oxygen production?
C. How does oxygen production relate to the rate of photosynthesis?
Question: In the Gizmo, what are the ideal conditions for photosynthesis? 1. Form hypothesis : During photosynthesis, light energy is used to synthesize carbon dioxide (CO 2 ) and water (H 2 O) into glucose (C 6 H 12 O 6 ) and oxygen (O 2 ). The complex series of chemical reactions is summarized by the following formula: 6CO 2 + 6H 2 O + light energy → C 6 H 12 O 6 + 6O 2 In the Gizmo, what light intensity and CO 2 level do you think will maximize the rate of photosynthesis?
2. Experiment : Use the Gizmo to find the ideal conditions for photosynthesis. Use any method you like. When you think you have the answer, list the conditions below.
3. Revise and repeat : One way to test if you’ve found the ideal conditions is to change each variable slightly from the value that you recorded above. If the oxygen production decreases with each change that you make, it is likely you have found the ideal conditions. If a small change causes oxygen production to increase, continue to experiment.