BIO 2 GO!
Most of the nitrogen on Earth is found in the atmosphere. Bacteria in the soil change the nitrogen found in the atmosphere into a form usable by plants.

In this unit you should learn how to do the following:
1.
Draw and explain the nitrogen cycle.
2.
Explain the role of bacteria in the nitrogen cycle.
3.
Distinguish between usable and non-usable nitrogen.
4.
Identify organic compounds made with nitrogen that are needed by all living organisms.
5.
Use the following words correctly: nitrogen nitrogen cycle bacteria atmosphere

Nitrogen is needed by all living things to create proteins and DNA. The process where nitrogen flows from the environment into living organisms and then is recycled back into the environment is called the Nitrogen Cycle. This cycle allows nitrogen to be available to all living things so they may grow and reproduce.
How the Nitrogen Cycle Works:
Most of the nitrogen is found as a gas in the atmosphere. In fact, most of what you breathe in is nitrogen, not oxygen. Unfortunately living things, including humans, cannot use the nitrogen that is found in the air. So, we simply breathe it out again.
There are certain bacteria found in soil that can turn the unusable form of
nitrogen into a form of nitrogen that is useful to plants. When these bacteria act on the unusable form of nitrogen they convert into a usable form of nitrogen.
Plants absorb this useful source of nitrogen into their roots and use it as a part of

the plant. When animals that feed on plants can then consume the nitrogen and use it for their body. So nitrogen changed from a gas in the atmosphere to become a part of a plant or animal.
When a plant or animal dies, the nitrogen is once again released by the
action of decomposers into the atmosphere. So the nitrogen changed from being a part of a plant or animal back into nitrogen gas in the atmosphere. The cycle begins again.
REMEMBER THIS !!!
Certain bacteria found in the soil are responsible for changing nitrogen into
a form that can be use by plants.
Question 1. How would you explain the nitrogen cycle?
The movement of nitrogen between the earth and the atmosphere where bacteria play an important role.
Question 2. What would happen if all of the bacteria in the ground stopped working?
The nitrogen cycle would stop working and living organisms would die.
Question 3. What is nitrogen used for in living organisms?
It is used to create proteins and DNA.
Interesting Scientific Fact: 78% of the air we breathe is nitrogen. None of it is useful to plants or other animals.

Nitrogen is a very important element to living things. Nitrogen atoms are found in DNA, RNA, proteins and ATP. Nitrogen atoms must be used over and over again so that new molecules can be made and used by all living things.
In the atmosphere, nitrogen gas is the most abundant gas. Plants and animals cannot use nitrogen gas, but certain bacteria can change it into a usable form. Certain bacteria are able to change nitrogen gas into a different
molecule that is usable by plants. These bacteria live in the soil. So the useful nitrogen molecules they make are found in the soil. Because of this, plants can take these useful nitrogen molecules into their roots and use them to make DNA,
RNA, proteins, and ATP.
Once a plant is consumed by an animal, the nitrogen is transferred to
the animal. Animals also need to make DNA, RNA, protein, ATP. Animals must eat plants or other animals to get the nitrogen they need.
Plants and animals have nitrogen in the molecules of their bodies. When a plant or animal dies, the decomposition of their body returns molecules
containing nitrogen to the atmosphere. When they come into contact with certain soil bacteria they are changed into a useful form. Then plants use these molecules to make new molecules which can be consumed by animals. The plants and animals eventually die and are decomposed. Their nitrogen is then released into the atmosphere. This is the nitrogen cycle.

True or False
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__ 1. Nitrogen atoms are found in DNA and RNA.
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__ 2. Nitrogen atoms are found in proteins and carbohydrates.
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_ 3. Nitrogen is the most abundant gas in Earth’s atmosphere.
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__ 4. Nitrogen gas in the atmosphere is taken in by plants and used for photosynthesis.
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__ 5. Nitrogen gas in the atmosphere cannot be used by plants.
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__ 6. Nitrogen gas in the atmosphere cannot be used by animals.
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__ 7. Nitrogen gas in the atmosphere cannot be used by bacteria.
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__ 8. Some bacteria are able to change nitrogen gas into a different molecule that plants can use.
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__ 9. Plants take molecules containing nitrogen into through their roots.
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__ 10. Animals eat plants or other animals to get the nitrogen they need.
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__ 11. Animals return nitrogen to the atmosphere when they decompose.
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__ 12. Animals return nitrogen to bacteria.
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__ 13. The decomposition of dead plants and animals returns nitrogen containing molecules to the air.
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__ 14. . The decomposition of dead plants and animals returns nitrogen containing molecules to the soil.
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__ 15. Bacteria are able to change nitrogen contain molecules into atmospheric nitrogen.

- Two words will be used twice.
DNA proteins
RNA atmosphere
ATP bacteria plants animals waste
1. Nitrogen is very important to _
Plants
______, __
Animals
______ and
__
Bacteria
_______.
2. Bacteria convert nitrogen in the _
Atmosphere
____ to a molecule that plants can take into their roots.
3. Once nitrogen containing molecules are in their roots, plants can make molecules like _
DNA
_____, _RNA______, __
Proteins
___, and __
ATP
_________.
4. _
Animals
________ must also make these molecules so they eat plants to get nitrogen containing molecules.
5. Animals return nitrogen to the soil in their _
Waste
_______.
6. _
Bacteria
________ can convert nitrogen containing molecules back to gaseous nitrogen.
1. What molecules in living things contain nitrogen?
DNA, RNA, proteins, and ATP
2. How does nitrogen in the atmosphere get into nitrogen containing molecules in the soil?
By bacteria who turn it into a useable form.

3. How do plants get nitrogen?
By taking the nitrogen compounds made by bacteria up through their roots.
4. How do animals get nitrogen?
By eating plants.
5. How is nitrogen gas returned to the atmosphere?
Trough the waste of animals or the decomposition of living organisms.
6. Draw and explain the nitrogen cycle.
Student pictures will vary.