1. Can plants take up all of the CO 2 in the atmosphere?

2. Think about the atmosphere around you. What is it made of?

3. Earth’s Atmosphere 78% nitrogen 21% oxygen 1% argon 0.038% carbon dioxide (CO 2 ) and traces of hydrogen, helium, and other "noble" gases

4. What happens elements in the atmosphere? Do they just stay in place or move around? Why?

5. Reactions The earth is a system where reactions that maintain life are fueled by sunlight. Almost all chemicals are fueled by living organisms Reactions are happening all around you, reactions that you cannot see! http://www.chem.ufl.edu/~itl/2045/lectures/lec_3.html

6. Photosynthesis is a reaction Photosynthetic organisms capture the energy in sunlight and convert the bonds between carbon and oxygen in CO 2 to weaker bonds that characterize life. All sorts of reactions can take place to store energy in the form of sugar molecules

7. CO 2 in the atmosphere is increasing Scientists have measured the CO2 in the air at Mauna Loa, Hawaii

8. What else do plants need to grow? Plants use light energy to change CO 2 and water into food substances (sugars). But, plants also need nutrients! Primary nutrients are nitrogen (N), phosphorus (P), and potassium (K) Secondary nutrients are calcium (Ca), magnesium (Mg), and sulfur (S)

9. Let’s look at one nutrient in particular. Why do plants need nitrogen? Nucleotides for DNA and RNA Plants need these nitrogen compounds to make amino acids, the base of proteins We all need protein! But where do plants get their nitrogen? Photo of DNA base pairs above: http://cyberbridge.mcb.harvard.edu/dna_1.html http://cyberbridge.mcb.harvard.edu/dna_1.html

10. Nitrogen Fixation 1% comes from lightning 99% is biological: bacteria can convert N 2 into NH 3 using an enzyme called nitrogenase Although a lot of bacteria and archaea can do this, it is very energetically expensive to break this triple bond

11. Nitrogen can limit growth of trees Most plants grow under conditions of nitrogen deficiency. That means if you add nitrogen to plants, they have enough of all other nutrients to grow more. That is why farmers add nitrogen fertilizer to their fields!

12. Global Change Humans are increasing CO 2 in the atmosphere Some scientists have suggested that as the concentration of CO 2 rises, plants can take up in their biomass Will nitrogen fixation provide enough nitrogen to keep plants growing as CO 2 increases?

13. Can plants keep up? You will be divided up into four focus groups: – (1) Why do we care about carbon dioxide (CO 2 ) in the environment? – (2) How are nitrogen and carbon related? – (3) How are nutrients added to ecosystems? – (4) How are nutrients lost from ecosystems? Can we run out of nutrients? In Part II you will design an experiment to test the question: Will plants grow with increasing CO 2 ?

14. Meet a Scientist Michelle Wong is graduate student studying ecology and evolutionary biology at Cornell University in Ithaca, NY. She is interested in how humans impact the carbon and nitrogen cycle. When she isn’t studying science, she likes to bake, rock climb, and spend time with friends and family.