Research by Michigan State indicates that students have a very limited understanding of how the global carbon cycle works. See What Carbon Cycle? College Students Lack Scientific Literacy, Study Finds Specifically, this research indicates that students do not understand the processes that transform carbon compounds nor do they understand that most of a tree's growth comes from atmospheric CO2 and water. Lab 1 is designed to address these misconceptions and lack of understanding of basic carbon cycle processes that underpin the carbon cycle.
In Part A: Students view a TedEd video to consider the question, "Where does a tree get its biomass?" They analyze images to trace the pathways of carbon between trees, soil and the atmosphere. Time estimate: 1 class period.
In Part B: Students go into the field to measure the carbon stored in a local tree. They use allometry to calculate the mass of carbon stored in their local tree.
For each group:
- A local, nearby tree - preferably having a circumference of 38cm (15 inches) or more.
- A regular flexible tape measure that will fit around the circumference of the tree; or a diameter tape measure; and/or a long string, marker and push pin
- Tree identification guide and/or tablet APP such as Leafsnap
- Calculator/pencil/paper NOTE: Calculators with exponents capability are required.
- A copy of the table "Allometric Coefficients for Common North American Trees." NOTE: See "Printed Materials" section below.
- A Student Data Worksheet to fill in their data and calculations.
For the class:
- Access to a spreadsheet program such as Microsoft Excel and Apple's Numbers
- (Optional) Soil testing kits and meters for testing environmental variables such as NPK(fertilizer), soil moisture, soil pH, soil temperature etc.
- A regular flexible tape measure that will fit around the circumference of the tree; or a diameter tape measure; and/or a long string, marker and push pin. NOTE: For larger trees, the string, marker and push pin may work best.
Time estimate: 2 class periods.
In Part C: Students carry out 4 investigations to learn how carbon compounds can be transformed into new, different carbon compounds.
In Investigation 1, students look for evidence of a chemical change when they bubble CO2from their own breath into limewater (calcium hydroxide) producing two new compounds: calcium carbonate and water. For the class: NOTE: This first part is done as a class demo. However, the entire investigation can easily be done as a DEMO.
- piece of chalk
- white vinegar
- eyedropper
For each group:
- clear plastic cup partially filled with limewater
- clear plastic cup partially filled with water
- empty clear plastic cup
- two drinking straws
- small (#2) coffee filter
- water
- white vinegar
- eyedropper
In Investigations 2 and 3, students use molecular model kits to model photosynthesis, respiration and biosynthesis of large, complex biomolecules built from multiple glucose molecules. For each group of 2-4 students:
- A plastic baggie that contains 6 CO2 molecules and 6 H2O molecules. If you have nitrogen atoms available to use, you may want to consider using these in Investigation 3.
Carbon Dioxide and Water Molecules
Provenance: candace dunlap
Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.
Molecular Model Kit for Photosynthesis and Cellular respiration.
Provenance: Product image from company Mega Molecules
Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.
For the class:
- Ball and stick molecular model kit(s) that contain carbon atoms, hydrogen atoms, oxygen atoms and bonds. You can purchase One Mega Molecule kit for Photosynthesis and Cellular Respiration from Amazon.com. Alternatively, a "Molecules of Life" kit may be purchased through any major science catalog such as Carolina Biological. You will need 6 carbon atoms, 12 hydrogen atoms, 18 oxygen atoms and 36 bonds to build 6 carbon dioxide molecules and 6 water molecules needed for each group.
- NOTE:
- Based on the number of students in your class and the size of the groups, you may need to order a second kit.
- You may want to considering ordering and using nitrogen atoms for building more complex molecules. If you have a "Molecules of Life" kit in your science department. you can use the nitrogen atoms that come with that kit.
In Part C, Investigation 4, students investigate what types of elements (atoms) carbon compounds can be made of by analyzing JMOL images of several plant-produced carbon compounds. This introduces students to the role of soil nutrients (nitrogen, phosphorus, sulfur, magnesium and iron etc) in building carbon compounds.
Each student will need:
- Paper or lab notebook to create their CHNOPS chart;
- Jmol color coding chart. This chart is embedded in the Part C student pages;
For the class (Optional):
- Use the MolView interactive Jmol biomolecule visualization web app to allow students to rotate, zoom-in and find background information on biomolecules. For a tutorial and more information about MolView, check out this Using MolView YouTube video ahead of time. NOTE: MolView uses ribbon diagramming for protein structures, so the molecular images of DNA and Cytochrome C on the student page for Lab 1C will not look the same in MolView.
Time estimate: 2 class periods
In Part D, students use videos, graphs and interactives to explore the combustion of fossil fuels and increased fossil fuel emissions to the atmosphere since the beginning of the Industrial Revolution. Students analyze graphs and videos to determine if the human activity of burning fossil fuels is changing the chemical composition of the atmosphere.
Time estimate: 1-2 class periods