Photosynthesis Gizmo Lab - Ms. Guirguis



Photosynthesis Gizmo Lab

1. Photosynthesis and Light Intensity

What is the relationship between light intensity and the rate of photosynthesis? In this activity, you will measure the rate of photosynthesis at different light intensities. Since oxygen (O2) is produced during photosynthesis, you can use the rate of oxygen production as an indicator of the rate of photosynthesis.

In the Gizmo™, observe the aquatic plant. During photosynthesis, the plant produces oxygen, which is visible as bubbles leaving the plant. Set the Light intensity to 0%. (To quickly set a slider to a specific value, type the number in the field to the right of the slider and press Enter.) Check that the Temperature slider is set to 30.0°C and the CO2 level is set to 500 ppm. Then select the Bar Chart tab and click on “show numerical values”.

a. What is the rate of oxygen production? ____________

b. What does this tell you about the rate of photosynthesis when no light is present?

Now slowly drag the Light intensity slider to the right.

a. What happens to the rate of oxygen production as the light intensity increases?

b. What does this tell you about the rate of photosynthesis as the light intensity increases?

Next select the TABLE tab. You will now use the table to record data on oxygen production at different intensities of light.

a. Set the Light intensity to 0%. Click on the Record Data button to record this information in the table.

b. Record the oxygen production when the light intensity is 10%, 20%, 30%, and so on up to 100%. Be sure to click on Record Data each time so all of the data is recorded in your table. Does your data agree with your findings? Explain.

2. Photosynthesis and Carbon Dioxide level

Now we will look at the affects of carbon dioxide on oxygen production. First set the Light intensity slider to 90% and the Temperature to 30.0°C. Set the CO2 level slider to 0.0%. What is the rate of oxygen production when there is no carbon dioxide available? ____________ (Find this in the bar chart)

Slowly drag the CO2 level slider to the right.

a. What happens to the rate of oxygen production as the CO2 level increases?

b. What happens when the CO2 level exceeds 300 ppm? ______________________

Make a table of the data to see if you are right.

3. Photosynthesis and Temperature

The production of sugars in photosynthesis is the result of a sequence of chemical reactions. Each reaction is sensitive to the temperature at which it takes place. Depending on their environments, different plants will undergo photosynthesis most efficiently at different temperatures.

Set the Light intensity to 90% and the CO2 level to 1000 ppm. Set the Temperature to 0.0°C and select the BAR CHART tab.

a. What is the oxygen production when the water temperature is 0.0°C? ________

b. What does this tell you about the rate of photosynthesis when the temperature is 0.0°C?

Slowly drag the temperature slider up.

a. What happens to the rate of oxygen production as temperature is increased?

b. What happens to the rate of oxygen production when the temperature exceeds 25°C?

4. Photosynthesis and Color

Play around with the color to see which color slider to see the affects of wavelength on oxygen production. Which color light produces the most oxygen?

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