Student Exploration: Photosynthesis Lab
Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes.
Vocabulary : carbon dioxide, chlorophyll, glucose, limiting factor, nanometer, photosynthesis, wavelength
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
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.
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| Photosynthesis Lab Assignment |
Observe the left pane closely. What do you think the bubbles are?
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?
- Experiment with the vertical Temperature slider (upper left) and the CO 2 level slider.
- Name: Sivaareni Selvakumar Date: March 3rd, 2021
- To survive, what gas do we need to breathe in? Oxygen
Where is this gas produced? Photosynthesis
- I think the bubbles are bubbles of oxygen
- When the light intensity increases the oxygen production also increases
A. How does temperature affect oxygen production?
oxygen production decreases when the temperature is over 31 degrees and increases between 17 and 31 degrees
B. How does CO 2 level affect oxygen production? When the CO2 level is under 230ppm oxygen production decreases, when the CO2 levels are over 230ppm the
Question: In the Gizmo, what are the ideal conditions for photosynthesis?
- 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?
- 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.
- 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.
If necessary, revise your numbers in the table above.
- Think and discuss: Think about the process of finding the ideal conditions
oxygen production doesn’t change
C. How does oxygen production relate to the rate of photosynthesis?
When the rate of photosynthesis increases the oxygen production increases
Activity A:
Ideal conditions
Get the Gizmo ready: Be sure that the BAR CHART tab is selected. Turn on Show numerical values .
I think the light intensity will go up to about 80-90% and the CO2 level will go up to about 700ppm
Temperature Light intensity CO 2 level Oxygen production 24.0 88.0 620 51.
A. Why would it be hard to find the ideal light intensity if the temperature were very hot or cold?
If it’s too cold or too hot photosynthesis would not occur because enzymes would be denatured
B. Which colors were absorbed the worst?
- Think and discuss: When we look at a leaf, we see the colors of light that are reflected off its surface. How does this explain the relatively low flow of oxygen in green light?
Introduction: Photosynthesis requires light, water, and CO 2 to work. When one of these factors is in short supply, it is called a limiting factor . Temperature can also be a limiting factor when it is too hot or too cold for photosynthesis to work well.
Question: What is the effect of limiting factors on photosynthesis?
- Observe: Set Temperature to 24°C, Light intensity to 50%, and CO 2 level to 200 ppm.
- Analyze: In this situation, what was the limiting factor?
Red, green and purple
There’s low flow of oxygen in green light due to the denaturation of the enzymes so photosynthesis wouldn’t occur because there’s no energy resulting in little oxygen production
Extension:
Limiting factors
Get the Gizmo ready:
Select the WHITE tab and the BAR CHART tab. ● Turn on Show numerical values .
A. Move the Temperature slider up and down. Were you able to increase oxygen production? (Return the slider to 24°C when finished.)
The oxygen production was only able to decrease or stay the same not increase
B. Move the Light intensity slider back and forth. Were you able to increase oxygen production? (Return the slider to 50% when finished.)
The oxygen production was only able to decrease or stay the same not increase
C. Move the CO 2 level slider back and forth. Were you able to increase oxygen production? (Return the slider to 200 ppm when finished.)
When the CO2 levels increased the oxygen production increased
The CO2 was the limiting factor
How do you know?
- Challenge: In each of the situations below, use the Gizmo to find the limiting factor.
- Think and discuss: Suppose you were a farmer trying to grow plants in a greenhouse. Why would it be important to know what the limiting factor is?
Because only when the CO2 levels were changed it would affect the oxygen production
Temperature Light intensity CO 2 level Limiting factor 25°C 60% 700 ppm light intensity 15°C 20% 200 ppm temperature 30°C 50% 400 ppm none
As a farmer knowing what the limiting factor is can help the farmer know what to make adjustments to allow the plants to grow better.
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