Model Code of Ethics for Educators

Name: Date: Student Exploration: Carbon Cycle Vocabulary: atmosphere, biomass, biosphere, carbon reservoir, carbon sink, fossil fuel, geosphere, greenhouse gas, hydrosphere, lithosphere, photosynthesis Prior Knowledge Questions (Do these BEFORE using the Gizmo.) In the process of photosynthesis, plants take in carbon dioxide (CO2) from the atmosphere and water (H2O) from the soil. Using the energy of sunlight, plants build molecules of glucose (C6H12O6) and oxygen (O2). 1. How do plants on Earth affect the amount of carbon in Earth’s atmosphere? Plants take carbon from the atmosphere to photosynthesize 2. Animals eat plants and produce carbon dioxide and water. How do animals affect the amount of carbon in Earth’s atmosphere? When animals eat food, they get carbon in the form of carbohydrates and proteins Gizmo Warm-up The Carbon Cycle Gizmo allows you to follow the many paths an atom of carbon can take through Earth’s systems. To begin, notice the black carbon atom in the Atmospheric CO2 area, highlighted in yellow. The glowing blue areas represent possible locations the carbon atom could go next. 1. From Earth’s atmosphere, where can the carbon atom go next? The carbon atom can go to the oceanic CO2, land plants, and exposed rocks 2. Click on Land plants and read the description. How did the carbon atom get from the atmosphere to a plant? there through photosynthesis The carbon atom gets to the atmosphere of a plant it gets 3. Select Land animals. How did the carbon atom get from land plants into the animal? The carbon atom gets from land plants into the animal by being consumed 4. Select Atmospheric CO2. How did the carbon atom get from land animals back to the atmosphere? The carbon atom gets back from the land to the atmosphere by cellular respiration Activity A: Get the Gizmo ready: Carbon pathways  Click Reset. Introduction: Earth can be divided into four systems. The atmosphere is the air above Earth’s surface. The hydrosphere is composed of all of Earth’s water. The geosphere is the rocky, non-living part of Earth. The biosphere consists of all living things, including people. Some scientists use the term “anthroposphere” to describe everything made or modified by humans. Question: How does carbon move between the atmosphere, hydrosphere, biosphere, and geosphere? 1. Explore: Use the Gizmo to create a path for carbon that begins and ends in the atmosphere. Fill in the steps in the path below. Then, label each location with the system it represents. Finally, summarize very briefly how the carbon atom got to that location. Carbon path System How it got there Atmospheric CO2 Atmosphere Atmospheric CO2 comes from volcanoes, burning fossil fuels, and other sources. Oceanic CO2 Hydrosphere Carbon dioxide dissolves into cold ocean surface waters. The colder the water, the more CO2 can be dissolved Shells/coral Hydrosphere and biosphere Marine animals use dissolved oceanic CO2 as a source of carbon for their calcium carbonate shells and skelotons. Oceanic CO2 hydrosphere In the deep ocean, calcium carbonate shells dissolve, releasing carbon dioxide back into the oceans Marine plants and algae Biosphere/hydrosphere In the process of photosynthesis, marine algae and plants remove carbon dioxide from ocean water, forming glucose and oxygen. Marine animals biosphere Marine animals consume marine plants and algae for energy. Oceanic CO2 hydrosphere Marine animals and plants break down glucose to produce energy 2. Create: Click Reset. Use the Gizmo to create a path in which the carbon atom goes from the atmosphere to the hydrosphere, biosphere and geosphere. Describe each transition briefly. Atmosphere Hydrosphere Biosphere Geosphere Atmospheric CO2 Oceanic CO2 Marine plants/algae/animals Sediments Volcanoes, burning fossil fuels, and other sources. Rainwater breaks down exposed rocks (Activity A continued on next page) During photosynthesis marine plants and algae remove carbon dioxide Uneaten plants and algae drift down to the ocean floor and become part of marine sediments Activity A (continued from previous page) 3. Explore: Use the Gizmo to create three more carbon paths, each starting and ending in the atmosphere. Label each location with A for atmosphere, B for biosphere, G for geosphere, or H for hydrosphere. (You can also use P for anthroposphere if you like, or just include it in the biosphere.) Path 1: atmosphere: Carbon path: atmospheric CO2: this arises from geological sources such as volcanoes, burning fossil fuels, etc. this gets carbon dioxide into the atmosphere during this process Path 2: geosphere Lithosphere: earths carbon has been researches to have large limestone deposits. This limestone can be found in the earths lithosphere. Through the heating of limestone, carbon dioxide gets back to the atmosphere Path 3: hydrosphere Carbon path: oceania CO2: there is a large deposit of dissolved CO2 underneath the ocean. As the ocean gets colder, it dissolves more. The plants absorb carbon dioxide through photosynthesis and gets back to the atmosphere 4. Explain: Based on the Gizmo, explain how the following transitions might take place: A. Describe at least two ways that carbon can get from a land plant to the atmosphere. Carbon is released from the plant into the atmosphere through the process of respiration in the form of carbon dioxide And decomposition B. Describe at least two ways that carbon can get from the atmosphere to the hydrosphere. Carbon dioxide automatically dissolves in cold ocean surface water; another way is when carbon dissolves in rainwater which later reacts with minerals in rocks C. Can you find two ways that carbon can get from the ocean to the lithosphere? (The lithosphere is the rigid layer of the Earth, including the crust and part of the mantle.) Ocean to the lithosphere is through the marine plants and animals, sediments, petroleum than to the lithosphere; the second way is through the shells and coral =, limestone then to the lithosphere D. Describe at least two ways that carbon can get from seashells to the atmosphere. Crashing of tectonic plates; and odd bleaching of volcanoes Activity B: Human activities Get the Gizmo ready:  Click Reset. Introduction: Fossil fuels, such as coal, oil, and natural gas, formed over millions of years from the remains of ancient plants and animals. The burning of fossil fuels, as well as other human activities, increases the amount of carbon dioxide in the atmosphere. Question: How does human activity affect the carbon cycle? 1. Describe: Using the Gizmo, determine how coal and petroleum (oil) are formed. Describe the steps required to form each fuel from atmospheric CO2. Coal: the atmospheric carbon dioxide must be transferred to the land plants with photosynthesis. Plants can accumulate in swamps and become burried down. There it is compressed, heated, and transformed into coal Petroleum: the atmospheric carbon dioxide must be transferred to the land palnts with photosynthesis. Once these plants die, they rot and get absorbed into the earth’s soil. This soil is washed into the streams and rivers, eventually forming layers of sediment. As these sediments continue to pile up, the lower areas begin to become increasingly compressed and heated. Petroleum and natural gas is formed and extracted from wells. 2. Explore: Natural gas is a mixture of methane (CH4), ethane (C2H6), and other gases. Find two ways that natural gas forms. List the steps of the two carbon pathways below: Path 1: atmosphere  oceanic CO2  marine plants/algae  sediments  natural gas  atmospheric CO2 Path 2: atmosphere  land plants and animals  natural gas  atmospheric CO2 How is the formation of natural gas related to the formation of coal and petroleum? are all formed in a similar way. Through heat and pressure All 3 3. Describe: Fossil fuels are used in many ways. Using the Gizmo, describe the main use for each fuel. Coal: used in power plants to generate electricity Petroleum: can be refined into gasoline and other fuels Natural gas: also used in power plants to generate electricity In each case, what is the end product of burning the fossil fuel, and where does it go? The eventual end product for each fossil fuel is as some sort of energy/ power source (Activity B continued on next page) Activity B (continued from previous page) 4. Explore: Another major contribution to atmospheric carbon dioxide is the cement industry. Using the Gizmo, find a carbon atom path from the atmosphere to the cement plant. (Hint: One of the ingredients in cement is limestone.) Path: atmosphere  oceanic CO2  shells/coral  limestone  cement plant How is carbon dioxide produced in a cement plant? calcium oxide and carbon dioxide Limestone is heated to produce 5. Analyze: Click Reset, then navigate to the Land animals. Select Atmospheric CH4. A. How do land animals create methane? Bacteria break down undigested materials and produce methane gass B. Humans raise large numbers of cattle for food. How will these herds of cows affect Earth’s atmosphere? When they eats plants, they are transferring the carbon from the plants to themselves. When they eat, they create waste and this waste produces methane 6. Analyze: In many tropical rainforests, people clear land by cutting down trees and burning them. After a few years, the soil runs out of nutrients and cannot be farmed any longer. How does this practice of “slash and burn agriculture” affect Earth’s atmosphere? During the process of making cement, the cement plant produces carbon dioxide 7. Draw conclusions: In general, how do many human activities influence the carbon cycle? This releases large amounts of CO2 into the atmosphere. Also, since there are fewer trees, it is harder for them to process the CO2 Activity C: Modeling the carbon cycle Get the Gizmo ready:  Select the MODEL tab. Introduction: Humans have been burning fossil fuels rapidly for the past 250 years. As a result, the amount of atmospheric CO2 has increased by about 40% since the year 1800. By measuring how much carbon moves into and out of the atmosphere, scientists can predict the change in the amount of atmospheric carbon dioxide every year. Question: How can we model changes in atmospheric carbon over time? 1. Observe: The MODEL tab shows a simplified model of the carbon cycle. The ovals represent carbon reservoirs, where carbon is stored. The unit “GtC” stands for gigatonnes of carbon, where one GtC is equal to one trillion kilograms of carbon. The arrows represent how much carbon moves from one reservoir to another each year, in gigatonnes per year. A. Look at the arrows pointing toward atmospheric CO2. What are the two major sources of atmospheric carbon? Oceanic CO2 and sediments B. A carbon sink is a location that stores carbon for a long period of time. Which two carbon sinks remove carbon from the atmosphere? Land plants and soil C. Without changing the Gizmo, list the carbon reservoirs from largest to smallest. Oceanic CO2, sediments, fossil fuels, atmospheric CO2, and land plants Note: The largest carbon reservoir is actually Earth’s lithosphere, which contains about 80,000 GtC. However, there is not much exchange between the lithosphere and the other reservoirs on short time scales. 2. Experiment: If necessary, click Return to original settings. These settings approximate present-day conditions, but should not be taken as exact values. A. What is the total amount of carbon removed from the atmosphere each year by the ocean and land plants? 65gtc B. What is the total amount of carbon added to the atmosphere from soil and the burning of fossil fuels? 69gtc C. How much will atmospheric carbon change in one year? In 10 years? 44gtc (Activity C continued on next page) In 100 years? 4gtc 444gtc Activity C (continued from previous page) 3. Calculate: Carbon dioxide is a greenhouse gas that helps to trap heat in Earth’s atmosphere. We need some CO2 in the atmosphere to maintain a warm planet, but excess carbon can cause considerable warming of the planet. A. What fossil fuel usage will result in no change in atmospheric CO2 each year? None of it B. What percentage decrease in fossil fuel usage is required to achieve this goal? 40% 4. Experiment: Using the Gizmo model, explore the following questions: A. How does increasing plant biomass (amount of plants) affect atmospheric CO2? It lowers it B. How does increasing oceanic CO2 intake affect atmospheric CO2 and oceanic CO2? It lowers the carbon dioxide in the atmosphere and raises the amount in the ocean As carbon dioxide is absorbed by the ocean, the ocean becomes slightly more acidic. This could make it harder for many organisms to build their shells and skeletons. The consequences of ocean acidification are not yet fully understood. 5. Infer: Click Reset and Return to original settings. Suppose we completely stopped burning fossil fuels immediately. How many years would it take to return to atmospheric CO2 levels from the year 1800, about 600 GtC? Use the Gizmo to find the answer. Around 50 years 6. Think about it: Since hard-shelled organisms evolved about 550 million years ago, billions of tons of limestone rock have been produced from their shells. Limestone is made of calcium carbonate, with the formula CaCO3. Based on this, how do you think the amount of atmospheric CO2 has changed in the last 550 million years, and how has this affected Earth’s climate? Explain your answer. I think it has changed greatly, it has affected earth’s climate in a negative way