Nitrogen Cycle Notes

Bio-geo-chemical cycles

Using the following diagrams, consider how nutrients cycle around the biosphere in the nitrogen cycle, carbon cycle, and water cycle.

​(remember you can

click on diagrams

to see them better)

Fill in the Blank

1. In the nitrogen cycle, bacteria complete ______ ______ and pull nitrogen in the atmosphere into organic molecules that they and other organisms can use.

Multiple Choice

2. Ammonium can be added to the soil by either the addition of fertilizer or by...

• bacteria taking it from plants

• plants taking in oxygen

• nitrates being released by bacteria

• decomposers breaking down organic material

Fill in the Blank

3. It's the nitrogen cycle because nitrogen can also return to the atmosphere. The process that turns nitrates or organic nitrogen into gas in the atmosphere is called...

When Nitrogen or other fertilizers run off from the soil, they can cause some populations to grow out of control. When these algae eventually die, their decomposition absorbs too much oxygen, making the area a dead zone.

Eutrophication

Multiple Choice

4. _________ from too much nitrogen can cause algae to overgrow. When they die, their decomposition uses up too much of the lake's ________.

• eutrophication... oxygen

• eutrophication... nitrogen

• respiration... oxygen

• respiration.... nitrogen

Similar to the nitrogen cycle, the carbon cycle charts how carbon-containing molecules move through the biosphere. We already know many of the biggest processes involved, including photosynthesis and respiration.

Carbon Cycle

Fill in the Blank

5. In the carbon cycle, carbon molecules can be released into the atmosphere by respiration, geological activity, and the explosive burning of carbon products, called....

Fill in the Blank

6. Gaseous CO2 is brought into biotic life during this process done by plants and some bacteria:

Multiple Choice

7. Abiotic (non-living) parts of the cycle are also important. Carbon can be moved through soil and water by...

• erosion and sedimentation

• consumption and decomposition

A last cycle that moves through biotic and abiotic life is the water cycle.

Water Cycle

Fill in the Blank

8. This process of __________ and precipitation (rain and snow) moves water from the atmosphere onto the surface of the earth.

Fill in the Blank

9. Water flows around the surface by runoff and ends up in lakes or the ocean. Other water uses _________ to get into the soil. This water is stored as groundwater.

Multiple Choice

10. Evaporation has gaseous water leave lakes and the ocean, while transpiration is the process of water moving out of plant leaves. Put them together to make the combined process called...

• infiltration

• condensation

• evapo-transpiration

• runoff

Review:

Nitrogen cycles the biosphere with the help of bacteria that fix it from the environment.

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Too many nutrients like nitrogen can cause eutrophication and algal overgrowth in bodies of water.

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Carbon cycles the biosphere through photosynthesis, respiration, and combustion by human activity.

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Water cycles through condensation, precipitation, runoff, infiltration, and evaporation/evapotranspiration