Carbon and Nitrogen Cycles
Interdependence within Environmental Systems
Background
Earth is a complex system. Everything in earth's system can be classified into one of several
subsystems that are often referred to as “spheres.” The “biosphere” is the combination of all of
the planet's ecosystems and is where all living organisms may be found. The biosphere includes
the atmosphere (air), the lithosphere (land), and the hydrosphere (all of the water on the planet
including oceans, lakes, rivers, and the water vapor in the air). As long as water is available, living
organisms have been found from many meters below the ground to several kilometers above
ground. Life is also found several kilometers below the surface of the oceans. Matter and energy
will cycle throughout the biosphere from one sphere to another according the law of conservation
of matter. This law states that matter can neither be created nor destroyed, but may only change
form. There are three very important substances that are cycled through earth's spheres, and
these are carbon, nitrogen, and water.
The atmosphere contains a mixture of gases. Listed below are the five most abundant gases found
in the atmosphere, including the trace amounts of other inert gases found.
Nitrogen (N2) – 78%
Oxygen (O2) – 21%
Water Vapor (H2O) – 1%
Argon (Ar) – 0.93%
Carbon Dioxide (CO2) – 0.04%
Inert Gases – 0.04%
The troposphere is the lowest layer of the
atmosphere (from the surface to 12km up).
It contains 75% of the gases found in the
atmosphere, a lot of water and dust, and is
the layer where weather occurs. In order
for life to exist and for weather to occur,
there must be water. The stratosphere is
the next layer of atmosphere (from 12km
to 31km above the surface). It contains
19% of the gases found in the atmosphere
with very little water vapor.
Complete the Background section of your Student Journal.
1
Carbon and Nitrogen Cycles
Interdependence within Environmental Systems
Part I: Your Role in the Ecosystem
Your teacher will assign you a role within an ecosystem group. You are to use the Student
Reference Sheet and prior knowledge to demonstrate how your role effects the environment,
specifically, the carbon and nitrogen cycles. Background information and all of the roles are found
within the Student Reference Sheet. You will be responsible to learn all roles and their
contributions found within the Student Reference Sheet.
Procedure:
1.  Your teachers will assign you a role and group.
2.  Learn how your assigned role contributes to and is affected by the carbon cycle and nitrogen
cycle.
3.  Work with your assigned partners and discuss how each role works together and influences
each cycle.
4.  Record your role and a brief description of its ecosystem effects in your Student Journal.
5.  Complete the Background section and Part I in your Student Journal.
Possible Roles in the Ecosystem:
Living
Non-living or System
Man-Made
Tree
Bunny
Wolf
Flower
Pine Beetle
Phytoplankton
Orca Whale
Legumes
Microorganisms
Algal Bloom
Bacteria
Ocean
Sun
Atmosphere
Lithosphere
Hydrosphere
Chemical Plant
Carbon Emissions
Waste Water System
Complete Part I of your Student Journal.
2
Carbon and Nitrogen Cycles
Interdependence within Environmental Systems
Part II: Disruptions in the Carbon and Nitrogen Cycles
Act out a skit, using all group members, to teach your classmates how each student's role in the
ecosystem is affected by a disruption to the carbon and nitrogen cycles. You are to show how each
person's role individually is affected, as well as how this disruption affects both the carbon and
nitrogen cycles together.
Procedure:
1.  Your teacher will assign your group one or multiple disruptions.
2.  Collaborate with your group members to discus how your ecosystem is affected.
3.  Plan your skit. Use any supplies that your teacher has provided for visual aide. Be sure to
show how each member's role is affected and how these roles are influencing and altering the
carbon and nitrogen cycles.
4.  Record your disruption and a brief description of its ecosystem effects in your Student Journal.
5.  While watching the other groups perform their skits, record their disruptions and effects as well.
Below are the disruption scenarios:
1. 
2. 
3. 
4. 
5. 
6. 
Volcanic eruption
Deforestation in a local forest
Increase in fossil fuel emission due to added power plants in an area
Decrease of a bacterial population that lives within the soil
Lightning strike
Increase in chemical fertilizers for plants
Prepare skit and complete Part II and the Reflections and Conclusions of your Student Journal.