1. The Nitrogen Cycle Major Processes: Nitrification Nitrification Denitrification Denitrification Decomposition Decomposition Assimilation Assimilation Nitrogen FixationNitrification Denitrification

2. Components of the Nitrogen Cycle N 2 (nitrogen gas) N 2 (nitrogen gas) In the atmosphere; cannot be used by plants or animals In the atmosphere; cannot be used by plants or animals NH 3 (ammonia) NH 3 (ammonia) Found in soil; cannot be used by plants or animals Found in soil; cannot be used by plants or animals NO 2 (nitrite) NO 2 (nitrite) Found in soil; cannot be used by plants or animals Found in soil; cannot be used by plants or animals

3. Components of the Nitrogen Cycle (Continued) NO 3 - (nitrate) & NH 4 + (ammonium) NO 3 - (nitrate) & NH 4 + (ammonium) Only compounds of nitrogen that plants can use Only compounds of nitrogen that plants can use Various nitrogen compounds such as amino acids Various nitrogen compounds such as amino acids Many different compounds that living things need for survival Many different compounds that living things need for survival

4. Processes of the Nitrogen Cycle Nitrification: The process by which unusable nitrogen compounds are changed into compounds used by plants and animals. The process by which unusable nitrogen compounds are changed into compounds used by plants and animals. Ex: Conversion of nitrogen gas (N 2 ) to ammonium (NH 4 + ) Ex: Conversion of nitrogen gas (N 2 ) to ammonium (NH 4 + ) Carried out by nitrogen-fixing bacteria Carried out by nitrogen-fixing bacteria Ex: Conversion of nitrogen gas (N 2 ) to nitrate (NO 3 - ) Ex: Conversion of nitrogen gas (N 2 ) to nitrate (NO 3 - ) Occurs when lightening strikes Occurs when lightening strikes

5. Processes of the Nitrogen Cycle Denitrification: The process of changing complex nitrogen compounds into atmospheric nitrogen The process of changing complex nitrogen compounds into atmospheric nitrogen Ex: Conversion of nitrate (NO 3 - ) to nitrogen gas (N 2 ) Ex: Conversion of nitrate (NO 3 - ) to nitrogen gas (N 2 ) Carried out by denitrifying bacteria Carried out by denitrifying bacteria

6. Processes of the Nitrogen Cycle Decomposition: The process of changing dead plants & animals into simple nitrogen compounds. The process of changing dead plants & animals into simple nitrogen compounds.Assimilation: The process of changing usable nitrogen compounds by plants into complex plant or animal nitrogen compounds. The process of changing usable nitrogen compounds by plants into complex plant or animal nitrogen compounds.

7. Switch to handout on Nitrogen Cycle

8. 1. 1. What source of energy ultimately drives the nitrogen cycle? Explain. The Sun: It gives plants the energy to absorb soil nitrates (NO 3 )- so the plant can make protein and grow. Back of Nitrogen Cycle Handout…

9. 2. How do animals obtain nitrogen as shown in Figure 3-13? Animals eat plant or animal protein to get “N”. They digest it and then use amino acids to make protein. Back of Nitrogen Cycle Handout…

10. 3. In what form does nitrogen appear in the air? Where does it come from? N 2 (nitrogen gas). Bacteria break down plant & animal protein and N compounds in soil. Back of Nitrogen Cycle Handout…

11. 4. What form on nitrogen are most plants able to absorb? How does it get into that form? Nitrates (NO 3 ) Special bacteria (nitrogen-fixers) are in little nodules on roots of certain plants- legumes. Ex: Clover, peanuts, soybeans, alfalfa You can cross out #5 on your sheet Back of Carbon Cycle Handout…

12. Mineral/Rock cycle Living organisms need other minerals, like Ca, Mg, Fe, etc. Living organisms need other minerals, like Ca, Mg, Fe, etc. They come from the releasing of minerals from rocks. They come from the releasing of minerals from rocks. So, how does the rock cycle work and how are minerals incorporated in the environment? So, how does the rock cycle work and how are minerals incorporated in the environment?

14. The mineral cycle * See page 33 of textbook

15. What to study: HW from textbook and any textbook readings HW from textbook and any textbook readings Class notes Class notes Food web diagrams, concept map, N,C and H 2 0 cycle diagrams Food web diagrams, concept map, N,C and H 2 0 cycle diagrams Vocabulary Vocabulary Case Study: Reintroduction of Wolves Case Study: Reintroduction of Wolves