The lab activity described here was created by Candace Dunlap of TERC for the EarthLabs project.
Use the button at the right to navigate to the student activity pages for this lab. To open the student pages in a new tab or window, right-click (control-click on a Mac) the "Open the Student Activity" button and choose "Open Link in New Window" or "Open Link in New Tab."
Investigation Summary and Learning Objectives
Students are briefly introduced to the essential role that carbon plays in life as we know it. They use videos, molecular model kits and a controlled experiment to explore the relationship between carbon dioxide, tree growth and environmental variables and to investigate the pathway of carbon from the air into tree biomass, food webs and the soil. Finally, they explore carbon molecules and important carbon cycle processes both by building ball-and-stick models and by interacting with Web-based molecules.
After completing this investigation, students will be able to:
- explain why carbon atoms can form the basis of millions of different types of carbon compound molecules.
- describe how the carbon atoms in CO2absorbed via plant photosynthesis provide the carbon atoms for all of the new carbon compounds a plant produces and uses to build its cells and tissues and to burn for energy.
- explain how carbon compounds are transformed in five chemical reactions that are critical to the carbon cycle: photosynthesis, cell respiration, decomposition, biosynthesis and combustion.
- answer whether trees and other plants can absorb ever-increasing amounts of carbon dioxide from the air or are limited by environmental factors.
For more information about the TOPIC, read the section titled Background Information under Additional Resources below
Activity Overview and Teaching Materials
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 nor do they understand that most of a tree's growth comes from atmospheric CO2 and water. Labs 1A and 1B are designed to address these mis-conceptions and lack of understanding of basic carbon 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 trace the pathway of carbon from the atmosphere into plants and then into food webs and soil. Next, students set up a controlled experiment, growing corn seedlings in hydroponically in fertilizer and non-fertilizer environment. This will allow students to determine the effect of nutrients (nitrogen, phosphorus, iron etc) on carbon storage in plants. Note: The plant experiment takes two - four weeks of growth. Teachers should consider starting the plant experiment two-four weeks before they start the module it they would like students to collect and analyze data at the end of Lab 1B. The longer the plants grow, the better the data. If not, students will not be able to collect the data until later on in the module.
In Part B: Students use molecular ball-and-stick models to explore carbon's potential for combining with other common elements such as hydrogen, oxygen, and nitrogen to form a variety of molecules. They "visualize" important carbon compounds such as chlorophyll and glucose by looking at their Jmol images. They can also interactively explore 3-D representations of these molecules accessing the molecules at the "World of Molecules" Web site–the Interactive Library. This site uses JAVA which could present from problems for schools. You easily see beautiful J-mol molecules on the IPAD app, "Nice Molecules." This app allows students to rotate and enlarge many different carbon compounds and access information about each molecule.
Lab 1A : Computer
Lab 1B Computer, JAVA downloaded to observe Jmol molecules in 3-D or use the IPAD app "Nice Molecules"
Lab 1A: One class for viewing and discussing the videos and reading the content.
Corn Plant experiment (2-4 weeks):
- Setting up plant experiment: One 45 minute class period
- Growing plants: Two-four weeks for plant growth. Consider setting up this experiment two - four weeks ahead of time.
- Collecting data, analyzing and discussing results. One - two 45 minute class period.
Lab 1A. Corn Plant Lab : See Experimental Protocol for Hydroponic Corn Growth System (Microsoft Word 2007 (.docx) 4.6MB Nov5 13) Corn Plant Lab Materials and Instructions
- Germination trays: several plastic /aluminum trays/pans at least 4 inches deep
- Corn Seeds - 16-20 per group
- Perlite/vermiculite mix - enough to fill germinating trays up to 4 inches
- 2-4 clear plastic 16/18 oz drinking cups per group
- 2-4 Styrofoam planting quads per group
- 8 -16 healthy-looking corn seedlings - per group
- Small amount of perlite/vermiculite to cover seedlings in the planting quad.
- Distilled or filtered water.
- Plant fertilizer such as Miracle Grow
- Fertilizer nutrient solutions (normal, low, high) made with distilled or filtered water.
- Laboratory mass balance – to decigrams or milligrams
- Plant light source –Plant GRO Lights, 100 Watt bulbs or a sunny part of the room.
- Graduated cylinder – 250 ml
- Spray mist bottle with 1-2 drops of dishwashing liquid in water
- Lab 1B. Organic molecule kits with carbon, oxygen, hydrogen atoms (nitrogen optional)
For each lab group, you will need in a plastic baggie with 6 CO2molecules and H2O molecules (12 carbon atoms, 12 hydrogen atoms, 18 oxygen atoms and 36 bonds).
There are three ways you can order the molecules:
1. Order a "Molecules of Life" kit. https://lab-aids.com/kits-and-modules/details/molecules-of-life-modeling Item # 505 $108.95
You will need to order two kits in order to have enough oxygen atoms. NOTE: The color of oxygen atoms in this kit is blue. Unfortunately, In the Jmol images, the oxygen atoms are red, and the nitrogen atoms are blue.
2. You can order "Molecules of Life "EXPAND -a-KIT" packages which provide enough material for one additional group of 4.
Item # = #505EL $12.25 per package You will need to order extra bags so you will have enough oxygen atoms.
3. You can order individual colors of molecules in packages of 100 @ approximately $14.95 per package (given the current price).
This is the best way to order them. It allows flexibility in ordering for the numbers and types of groupings you would like to do in your classroom and with a little bit of work, you can reconfigure them into the same color-coding system as the Jmol molecules by snipping off some prongs. These prongs snip off easily with a pair of scissors. See instructions below.
In order to get these molecules with the same color-coding as the Jmol molecules (black = carbon, red = oxygen, blue = nitrogen, white = hydrogen), you will have to call and ask for a special order. These items are not in the catalog so you will have to speak to a customer representative. (1-800-381-8003) Then, when you receive the materials, you will have to "reconfigure" the red nitrogen atoms(#530A-RT) into red oxygen atoms by snipping off two prongs according to the instructions in boldface type below.
# 530A-T5 Covalent bonds, 100/pk $14.65 per bag
#530A-BT Molecular Model Component, Tetrahedral Bond, Carbon Sp3 Hybrid (black), pk/100 $14.65 per bag (4 prong bonds)
#530A-WS Molecular Model Component, single bond, Hydrogen (white), pk/100 $14.65 per bag (1 prong bond)
#530 A-RT Molecular Model Component, Tetrahedral Bond, Nitrogen (red), pk/100 $14.65 per bag (for Jmol, red atoms are oxygen atoms so you will have to"reconfigure" these red atoms into oxygen atoms by cutting off two of the bond "prongs." Remember that oxygen forms two bonds.) So - to reiterate, you will be reconfiguring the red nitrogen atoms into oxygen atoms by cutting off two prongs.
Optional: If you want your students to make amino acids for an extension, you will need nitrogen atoms which in Jmol are blue with three prongs. You must order #530A-BT2 Molecular Model Component, Tetrahedral bond (oxygen blue) and cut one prong off.
Because the atoms come in bags of 100, you will need to determine how many bags of each type of atom (carbon, hydrogen, oxygen, covalent bonds) you will need to order to suit your personal needs (# of class groupings), For each lab group, you will need in a plastic baggie with 6 CO2molecules and H2O molecules (12 carbon atoms, 12 hydrogen atoms, 18 oxygen atoms and 36 covalent bonds). So expect to order many more bags of covalent bonds than bags of carbon, hydrogen and oxygen.
To download one of the PDF or Word files below, right-click (control-click on a Mac) the link and choose "Save File As" or "Save Link As."
- Experimental Protocol for Hydroponic Corn Growth System (Microsoft Word 2007 (.docx) 4.6MB Nov11 13) Students' Lab Instructions and Data Table: What is the Effect of Nutrients on Carbon Dioxide Uptake and Carbon Storage in Corn Plants: A Systems Thinking Approach.
- Elements in Biomolecules Chart (Microsoft Word 2007 (.docx) 137kB Nov5 13) Elements in Biomolecules Chart
- Stop and Think Questions Lab 1A and Lab 1B (Microsoft Word 2007 (.docx) 347kB Feb11 14)
- Suggested Answers to Stop and Think Questions Lab 1A and Lab 1B with answers (Microsoft Word 2007 (.docx) 371kB Mar4 14)
Teaching Notes and Tips:
Pre-Planning for the Plant Lab:
It is important that you soak your seeds the night before planting. Add 1-2 drops of dishwashing liquid to prevent mold and mildew. Because you are not germinating the seeds for a few days before planting, expect to add several days to the experiment before you see growth.
If you would like to be able to collect and analyze data from the plant experiment at the end of Lab 1A, consider setting up this experiment 2-4 weeks before you begin the "Climate and the Carbon Cycle" module.
In LAB 1A, students begin the module with by examining the capacity of trees and forests to remove CO2 from the atmosphere and sequester it in their tissues and structures. Trees are composed largely of water and a carbon compound called cellulose. Cellulose is the fibrous material that makes up the woody tissue of trees. The water content of trees varies from less than 10% of the tree's weight to more than 50%, depending on the species; the average is closer to 25%. The biomass (dry weight) of a tree comes essentially from cellulose - a complex carbon compound made of carbon, hydrogen, and oxygen atoms. More than 50% of that biomass comes from carbon. All of this carbon comes from atmospheric carbon dioxide. In the process of photosynthesis, carbon dioxide is combined with water to produce oxygen and the sugar that provides energy and building materials of carbon, oxygen and hydrogen atoms. See the fate of glucose in this image
Purpose of the discussion:
The first two discussions are related. The first is a formative prompt meant to uncover what misconceptions students may have about how trees grow. If students are to understand that plants and especially trees pull a lot of carbon out of the atmosphere, they need to grapple with the major misconception.
Write students hypotheses on the board.
After the video, have students revisit the hypotheses and talk about which hypothesis(es) must be rejected based on the information in the video.
Consider talking about what a misconception is and whether or not science misconceptions matter in understanding the world around us. Also discuss why so many people in the video had difficulty thinking about tree growth in terms of CO2.
What are plants made of? Consider beginning to talk about what plants are made of in terms of proteins, carbohydrates, Lipids and nucleic acids. Even though trees get hydrogen, nitrogen, phosphorus atoms etc from the soil all of the carbon to build these carbon compounds comes from the carbon taken in by plants from the air. This concept will be reinforced in Lab 1B. Consider using this diagram image
In LAB 1B, students build a myriad of carbon compounds from six carbon dioxide molecules and six water molecules - the same building materials that trees use to build their structures. Students will build a glucose molecule from 6 carbon dioxide molecules and 6 water molecules. Students need to construct an understanding of the many different forms and structures carbon compounds can take because of the bonding nature of carbon. The term "carbon compound" should be used throughout all of the investigations in this module, where appropriate. For classroom management, have students take apart the molecules they built before the end of class in order to prep for the next class coming in.
Purpose of the discussion:
All of these discussions are meant for students to get at the idea of the atoms in carbon compunds
Consider bringing up these molecules
Primary discussion questions:
Student NotebooksStudent notebooks are optional. Here are just a few suggestions for what to include in student notebooks for Lab 1:
- Plant experiment: research question, materials, protocol, observation, data, graphs, analysis questions
- Elements in Biomolecules chart
- Notes from videos
- Equations for the processes in Lab 1B: photosynthesis, respiration, decomposition, biosynthesis
- Additional research on biomolecules
Assessment:There are several options for assessments of students understanding of material produced in this Lab. Teachers can choose from the following list or create their own assessments.
- Assess student understanding of topics addressed in this investigation by grading their responses to the Stop and Think questions.
- Teachers may want to collect and grade the hands-on lab write-ups.
- Written Test for Lab 1 (Microsoft Word 2007 (.docx) 118kB Mar4 14) (Answer Key (Microsoft Word 2007 (.docx) 124kB Jan21 14))
National Science Teaching Standards
Lab 1 supports the following Next Generation Science Standards (NGSS):
Science and Engineering Practices
2. Developing and Using Models
3. Planning and Carrying Out Investigations
4. Analyzing and Interpreting Data
5. Using Mathematics and Computational Thinking
Disciplinary Core Ideas
LS2.B Cycles of Matter and Energy Transfer in Ecosystems
PS3.D Energy in Chemical Processes
LS1.C Organization for Matter and Energy Flow in Organisms
3. Scale, Proportion and Quantity
4. Systems and System Models
5. Energy and Matter
Background information:The NatureEducation Scitable site has multiple articles that can provide excellent background information for yourself and/or your students. These articles are more appropriate for AP level students. Knowledge Project at Scitable
Here are two examples: Effects of Rising Atmopshereic Concentrations of Carbon Dioxide on Plants
Determine the amount of carbon in a tree near you. Use this simple tree carbon calculator http://www.northsydney.nsw.gov.au/carbon/carbon.html
Explore visualizations of forests and vegetation created with data from the new NASA NPP Suomi satellite. NASA visualizations of forests and vegetation
Read about how scientists use remote sensing to map carbon in forests in Seeing Forests for the Trees and the Carbon; Mapping the World's Forests in Three Dimensions
Research various programs to plant trees such as the "Plant a Billion Trees" program at The Nature Conservancy.
Students research which types/species of trees in their location absorb and sequester the most carbon.
Use ScienceDaily to have students discover the latest research on carbon sequestration in forests. Some tags would include: carbon storage/sequestration in forests, nutrients and carbon storage/sequestration.
As part of Lab 1B, test the corn seeds for presence of biomolecules (proteins, carbohydrates (sugars and starches), fats. These testing kits which include Benedict's solutions for sugar, Lugol's for starch, Biuret's for proteins and Sudan's for fats can be purchased from most science supply catalogs such as Carolina's biological.
Read about the FACE carbon dioxide enrichment experiments