Earth Science/Biology Standard

7a. Students know the carbon cycle of photosynthesis and respiration and the nitrogen cycle.

What is nitrogen? Chemical element N, atomic number=7

Colorless, odorless, tasteless, inert gas

Makes up 78% of the atmosphere

N2,Dinitrogen gas, (Diatomic )

Why is it important? Proteins and nucleic acids (DNA, RNA)

in living organisms

Nitrogen gas (N2)-> cannot be used directly.

* Animals get nitrogen from plants or animals that ate plants

Forms of nitrogen Atmospheric Nitrogen: N2

Nitrate :NO3

Nitrite: NO2

Ammonia: NH4

What is the nitrogen cycle?•The process by which nitrogen is converted between its chemical forms

•It can be carried out by both biological and non-biological processes

•Bacteria are key element of the cycle

Where does it go?

• MicrobesMicrobes

Nitrogen fixationbreak apart N2 Atmospheric: lightning Biological: bacteria

Industrial: great pressure and temperature

Atmospheric Nitrogen and Nitrogen Fixation

Triple bond is very stable Nitrogen gas- ammoniaMainly through bacteria

Bacteria•Single celled

•Very small, microscopic

Nitrogen fixing bacteria

Bacteria living in root nodules of LEGUMES (soybeans, peanuts, alfalfa)

Bacteria living in soil and water

Assimilation Plants Nitrate->nitrite-> ammonium-> amino

acids, nucleic acids Ammonium-> amino acids, nucleic acids

(in legumes)

Animals eat plants amino acids, nucleotides

Mineralization (ammonification) Plant or animal dies, animal excretes

waste

Bacteria convert organic nitrogen to ammonium

Nitrification Bacteria convert ammonium to nitrate nitrite-> nitrate->ammonium Nitrate-> ammonium

Can seep into groundwater Health problems Environmental problems

Denitrification Bacteria convert Nitrate to Nitrogen

gas

Completes the cycle by returning nitrogen to the atmosphere

Increased Nitrogen emissions Cultivation of legumes

Artificial fixation of nitrogen

Nitrogen oxide from cars and factories(greenhouse gas, destroys ozone layer)

In water… Acidification

EutrophicationToo much nitrogen in the water (mostly

due to runoff from land) -> more algae (algal blooms) -> take up oxygen-> affects other organisms (animal lives die)

Earth Science/Biology Standards

7c. Students know the movement of matter among reservoirs is driven by Earth's internal and external sources of energy

What powers the water cycle?

What drives photosynthesis?(Carbon transfer: atmosphere->biomass)

The sun!

What type of energy is produced during cellular respiration and *decomposition?

What powers subduction zones?Energy transfer between hot interior and cool exterior

How?

Convectionmovement of molecules in liquids and gases, “flowing”

Coal Formation?Plants that died millions of years ago*Pressure by sedimentary rocks

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