Photosynthesis Lab Questions and Answers

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Vocabulary: carbon dioxide, chlorophyll, glucose, limiting factor, nanometer, photosynthesis, wavelength, chloroplast Prior Knowledge Questions (Do these BEFORE using the Gizmo.) As you work through ... the activity, answer at every green highlighted area. You must carry out the lab as instructed throughout the worksheet. ● To survive, what gas do we need to breathe in?__We need Oxygen to survive._ ● Where is this gas produced? _We get this gas from trees.__ Gizmo Warm-up During photosynthesis, plants use the energy of light to produce glucose (C6H12O6) from carbon dioxide (CO2), and water (H2O). 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? __It’s the oxygen being released into the air._ 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? __When there is no light the oxygen flow slowed down but when there was a lot of light the foxygen flow increased. 3. Experiment with the vertical Temperature slider (upper left) and the CO2 level slider. A. How does temperature affect oxygen production? __When the temperature gets low the oxygen will decrease, if the temperature is to high the oxygen level will still decrease._ B. How does CO2 level affect oxygen production? ___If it gets lower than 220 ppm it will decrease, if you add more there is no change. C. How does oxygen production relate to the rate of photosynthesis?___It tells you This study source was downloaded by 100000796615030 from CourseHero.com on 07-07-2021 06:42:26 GMT -05:00 https://www.coursehero.com/file/37423754/Copy-of-Gizmos-Photosynthesis-Lab-WS/ This study resource was shared via CourseHero.com how fast photosynthesis is happening. Activity A: Ideal conditions Get the Gizmo ready: ● Be sure that the BAR CHART tab is selected. ● Turn on Show numerical values. Question: In the Gizmo, what are the ideal conditions for photosynthesis?__light conditions are 30.0%, temperature is 30c, CO2 is 500 ppm, O2 flow is 46.1. 1. Form hypothesis: During photosynthesis, light energy is used to synthesize carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2). The complex series of chemical reactions is summarized by the following formula: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2 In the Gizmo, what light intensity and CO2 level do you think will maximize the rate of photosynthesis? The light intensity level will be 60%, and the CO2 will 630 ppm. 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. Temperature Light intensity CO2 level Oxygen production __25.00C __80%_ __690 ppm_ __51.8ml/h_ 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. If necessary, revise your numbers in the table above. 4. Think and discuss: Think about the process of finding the ideal conditions. A. Why would it be hard to find the ideal light intensity if the temperature were very hot or cold? ___If the temperature is to high or low than the oxygen flow will decrease ,if its to high like 46c, the oxygen flow will be 0.1 and if its to low like 10.0c it will be 3.1. B. Why would it be hard to find the ideal CO2 level if the light intensity were very low? __Very low amounts of 02 are produced when the light intensity is very low. This study source was downloaded by 100000796615030 from CourseHero.com on 07-07-2021 06:42:26 GMT -05:00 https://www.coursehero.com/file/37423754/Copy-of-Gizmos-Photosynthesis-Lab-WS/ This study resource was shared via CourseHero.com Activity B: Colored light Get the Gizmo ready: ● Select the COLOR tab and the BAR CHART tab. ● Set the Temperature to 24°C, the Light intensity to 90%, and the CO2 level to 1,000 ppm. Introduction: Plants use a green pigment called chlorophyll to absorb light and convert its energy into a form that the plant can use. Chlorophyll gives plants their green color. Question: What color of light is the best for photosynthesis?_Blue(450nm) __ 1. Observe: The color of a light wave is determined by its wavelength. On the COLOR tab, slowly drag the Light wavelength slider back and forth and observe the effect on oxygen production. How does the color of light affect the rate of photosynthesis?__When the color is to dark of to light the oxygen flow is not as good as colors like Blue and red._ 2. Form hypothesis: Which color of light do you think will maximize the rate of photosynthesis? _Blue and Red would maximize_it._ 3. Gather data: Set the Light wavelength to 400 nm. (The symbol “nm” stands for nanometers. A nanometer is a billionth of a meter.) Visible light ranges from 400 to 700 nm. On the TABLE tab, click Record data. Then set the Light wavelength to 420 nm, and repeat. Continue recording data in the Gizmo every 20 nm until the wavelength is 700 nm. 4. Make a graph: Select the GRAPH tab and select Wavelength. Sketch the graph in the space at right. A. Which colors were absorbed best by the plant? __Blue and Red _ B. Which colors were absorbed worst?__Green and Yellow_ 5. 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? _Green light is not absorbed therefore not used during PS. Extension: Limiting factors Get the Gizmo ready: ● Select the WHITE tab and the BAR CHART tab. ● Turn on Show numerical values. Introduction: Photosynthesis requires light, water, and CO2 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 This study source was downloaded by 100000796615030 from CourseHero.com on 07-07-2021 06:42:26 GMT -05:00 https://www.coursehero.com/file/37423754/Copy-of-Gizmos-Photosynthesis-Lab-WS/ This study resource was shared via CourseHero.com is too hot or too cold for photosynthesis to work well. Question: What is the effect of limiting factors on photosynthesis? 1. Observe: Set Temperature to 24°C, Light intensity to 50%, and CO2 level to 200 ppm. A. Move the Temperature slider up and down. Were you able to increase oxygen production? __no_________________ (Return the slider to 24°C when finished.) B. Move the Light intensity slider back and forth. Were you able to increase oxygen production? __no_________________ (Return the slider to 50% when finished.) C. Move the CO2 level slider back and forth. Were you able to increase oxygen production? __Yes__________________ (Return the slider to 200 ppm when finished.) 2. Analyze: In this situation, what was the limiting factor? _Co2__ How do you know? ___ Challenge: In each of the situations below, use the Gizmo to find the limiting factor. Temperature Light intensity CO2 level Limiting factor 25°C 60% 700 ppm Light 15°C 20% 200 ppm Temperature 30°C 50% 400 ppm none 3. 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? [Show More]

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