W. S. Cycles of Matter
Nitrogen and Phosphorus Cycles
Name _________________________
Date __________________ Per ____
Nitrogen Cycle
This interactive activity adapted from the University of Alberta illustrates how, through a process called
fixation, nitrogen flows from the atmosphere, into the soil, through various organisms, and back to the
atmosphere in a continuous cycle.
Once here, click the view button to start the Nitrogen cycle. Answer the following questions. If you need help,
click on the Background Essay box to the right and find the answer in the essay. You can select the “Pause”
button in the animation at any time and roll over the terms and elements or chemical formulas for more
information.
http://www.teachersdomain.org/resource/lsps07.sci.life.eco.nitrogen/
1.
The atmosphere is 80% nitrogen: why do you think plants and animals can't use nitrogen as it is found in
the atmosphere?
2.
Explain what is meant by nitrogen fixation.
3.
What is ammonification?
4.
Write the chemical formula for the form nitrogen is in during the next phase.
5.
Explain what is meant by nitrification.
6.
From Nitrification to Nitrification the chemical formula nitrogen is found in changes. What formula
does it change from and what formula does it change into?
7.
Explain denitrification.
8.
What is the chemical formula for nitrogen when nitrogen changes to go into the atmosphere?
9.
What is meant by assimilation?
10.
What is the role of bacteria in the nitrogen cycle?
11.
Why don't legumes need nitrogen-containing fertilizers?
12.
Why is nitrogen so important for living things?
Nitrogen Cycle
Use the following words to fill in the blanks for the Nitrogen Cycle. Use each word once.
Atmosphere
78%
ammonia
proteins
denitrificating
Nitrate
Nitrogen-fixing
plants
animals
waste
plants
1.
Our atmosphere is ______ nitrogen gas.
2.
Animals and plants cannot directly use all the nitrogen found in our ________________.
3.
Only special bacteria can directly use nitrogen in our atmosphere and “fix” it so other organisms can
benefit. These bacteria are called ____________-_________ bacteria.
4.
Higher organisms use nitrogen to make their _____________.
5.
Animal waste decay by the action of bacteria which create _____________and __________ products
rich in nitrogen, and useful for plants to use again.
6.
______________ bacteria in the soil can break down the ammonia into the gaseous form of nitrogen,
which is not available for use by plants or animals.
7.
In another part of the cycle, animals eat ____________ containing nitrogen, which is again returned to
the soil by animal _____________ or decaying ____________ and ___________.
8.
Draw a diagram of the Nitrogen cycle using the words in the text box.
Phosphorus Cycle
Phosphorus atoms are an integral part of many types of biological molecules and are essential to life. For
example, phosphorus atoms are a component of the chemical backbone of DNA – the genetic material of cells.
Phosphorus atoms are also found in phospholipids, which make up cellular membranes.
Once at this site, select the “Go to Animation” button. Select the “Step-Through” button and answer the
following questions. If select the narrated button, you will miss many answers to the following questions.
http://www.sumanasinc.com/webcontent/animations/content/phosphorouscycle.html
1.
Where is phosphorus found in the human body?
2.
What is the main source of phosphorus and how do organisms acquire phosphorus?
3.
How is the phosphorus released from rocks?
4.
Once we acquire the phosphorus, how is it released back into the soil?
5.
How does the phosphorus in the soil or rocks enter the earth’s water systems?
6.
What happens to the phosphorus once it enters the marine ecosystem?
7.
How long to scientists believe it takes phosphorus to become a rock again?
8.
Of the four cycles of matter, one does not enter the atmosphere. Which one?
9.
How does phosphorus get out of the water and back up into the land?
10.
List three methods that man has done to upset the phosphorus cycle.
11.
Explain how these methods have upset the balance of organisms in an ecosystem.
Once you are the web site, select the Phosphorus Cycle from the Animations list. This link will take you to an
interactive presentation of the Phosphorus Cycle. It is kind of small to read, but do your best to review the
material you learned at the previous web site.
http://highered.mcgraw-hill.com/sites/0072879351/student_view0/chapter10/animations.html#
Phosphorus Cycle
Use the following words to fill in the blanks for the Phosphorus Cycle. Use each word once.
Pollution
basins
rocks and minerals
waste
DNA
overgrowth
plants
1.
Phosphorus in NOT found in the free state in Nature, but is contained mostly in _______ and
______________.
2.
It is an essential nutrient for life, as it makes up important chemicals such as _______.
3.
In the Phosphorus Cycle, phosphorus moves between the soil and ___________, which are eaten by
animals. The animals use phosphorus, and then their ___________ products help return the phosphorus
for the next generation of phosphorus in the soil.
4.
Some of the phosphorus in soils can be washed away into water ___________.
5.
Another source of phosphorus in water comes from man-made _____________.
6.
Too much phosphorus in water leads to plant ________________, strangling all other life forms in the
water.
7.
Why is the use of phosphorus-rich products and fertilizers bad for the environment?
8.
How is the use of phosphorus-rich products and fertilizers good for organisms?