CarbonOxygenHydrogen????

Living things need nitrogen to make amino acids, which make up proteins

Nitrogen is part of nucleotides, which make DNA and RNA

Air 78% nitrogen 21% oxygen 0.02% carbon dioxide <1% other gases

Plants and animals cannot absorb nitrogen from the air

What problem does this pose for living things?

How does nitrogen get into living organisms?

What suggestions do you have? How can you imagine that living things could convert nitrogen into a form that they can use?

Miracle-Gro is made with ammonium phosphate, urea, potassium chloride, and other ingredients

Total Nitrogen: 15% Available phosphate: 30%;

The fertilizer is added to the soil and the plants absorb it

What about plants in the wild? Where does their nitrogen come from?

Waste from other living things

They cannot absorb it from soil or from the air

They cannot use ammonia or nitrates to make amino acids

Animals get nitrogen from eating plants

Decomposers break down the dead tissue and add it to the soil

The plants have the nitrogen available to them

Everyone please take a handout

Most nitrogen is released as ammonia NH3 (in urine and other waste)

Some is absorbed directly by plantsSome is converted to nitrate (NO3)

by bacteria (called nitrifying bacteria)

Plants can use nitrate (NO3)

Ammonia to nitriteNH3 to NO2 by nitrifying bacteriaPlants cannot absorb NO2 so another

step is neededNO2 (nitrite) to NO3 (nitrate) by

nitrifying bacteriaPlants can absorb and use nitrate

(NO3)

Denitrifying bacteria

They convert NO2 and NO3 back into N2 which is released back into the atmosphere

A different bacteria, called nitrogen fixing bacteria

These bacteria are found mainly in the roots of legumes (peas, soybeans, clover, alfalfa)

If there is not enough ammonia in the soil, these bacteria can make ammonia from the N2 in the air

There are living things that need nitrogen and other living things that are able to convert the nitrogen from the air to a form that is usable by plants.

Also, the remaining nitrogen can be returned to the air

How does the flow of matter in ecosystems compare with the flow of energy through ecosystems?

Matter (atoms) are recycled and none are lost

Energy is lost in the energy pyramid and must be replenished

What does it mean to rotate crops?Why do you think that farmers would

alternate crops, especially between legumes and non-legumes?

Due Thursday: Worksheet as review for the unit 2 test

Due Friday: First draft for the introduction section of the bottle ecosystem lab

It will also serve as a review for the exam

Web site has all the topics that should be included