Student Exploration: Photosynthesis Lab To survive, what gas do we need to breathe in? Oxygen Where is this gas produced? The gas is produced from plant life 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? When the light intensity is increased the oxygen production also is increased, the maximum oxygen production by light intensity seems to be reached by the middle bar. How does temperature affect oxygen production? A temperature that is too high or too low negatively affects oxygen production. How does CO2 level affect oxygen production? When there is no CO2 no oxygen can be produced. How does oxygen production relate to the rate of photosynthesis? When a plant is doing photosynthesis it releases oxygen. In the Gizmo, what light intensity and CO2 level do you think will maximize the rate of I think a medium light intensity and a CO2 level around 100-200. 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. Table Answers Below: Temperature 24.0 degrees Celsius Light Intensity 45 percent c02 Levels 450 ppm Oxygen Production 24.3 mL/h Why would it be hard to find the ideal light intensity if the temperIt would be hard to find the ideal light intensity as the level of light ature were very hot affects the temperature or cold? It would be hard to find the ideal CO2 level if the light intensity were Why would it be hard to find the ideal CO2 level if the light intensity very low because there would be less CO2 in that were very low? environment. Observe: The color of a light wave is determined by its wavelength. On the COLOR tab, Some colors allow for higher levels of photosynthesis as compared slowly drag the Light wavelength slider back and forth and observe to other colors of photosynthesis. For example 450 nm allows the effect on oxygen for a high level of photosynthesis. production. How does the color of light affect the rate of photosynthesis? Form hypothesis: Which color of light do you think will maximize the rate of photosynthesis? I think green will allow for the maximum rate of photosynthesis because it[ the same color as the chloroplast and plant. Which colors were absorbed best by the plant? 450 nm and 650 nm Which colors were absorbed worst? 550 nm, 700 nm, and 400 nm 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? The colors of the leaf reflecting off the leaf are not green Move the Temperature slider up and down. Were you able to increase oxygen production? No Move the Light intensity slider back and forth. Were you able to increase oxygen production? Nope! Move the CO2 level slider back and forth. Were you able to increase oxygen production? yepp Analyze: In this situation, what was the limiting factor? The co2 level 1/2 How do you know? Because if it were raised the oxygen flow would also have increased. Challenge: In each of the situations below, use the Gizmo to find the limiting factor. Answers for chart below: Temperature Row One - 25 C Row Two - 15 C Row Three - 30 C Light Intensity Row One - 60% Row Two - 20% Row Three - 50% Co2 Level Row One - 700ppm Row Two - 200ppm Row Three - 400ppm Limiting factor Row One - Light Row Two - Carbon DIoxide Level Row Three - Temperature 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? So you can change the limiting factor in a way that will benefit the plant's photosynthesis. 2/2