Water Cycle
Carbon Cycle
Phosphorus Cycle
Nitrogen Cycle
Human Impact
100

This step draws water back to Earth as rain, sleet, or snow thanks to gravity.

What is precipitation?

100

This step returns CO2 back into the atmosphere and is associated with breathing out.

What is respiration?

100

This step occurs when water moves over rocks, washing phosphorus into rivers and streams.

What is erosion/run-off?

100

This step is when the nitrogen in dead organisms is turned into NH4 (ammonium).

What is ammonification?

100

Deforestation decreases of this step of the water cycle.

What is transpiration?

200

This step involves water percolating (filtering through) from the surface through the soil and into aquifers.

What is infiltration?

200

This step occurs when something is burned, such as when you drive a car that runs on fossil fuels or a forest fire.

What is combustion?

200

This is the main phosphorus reservoir.

What are rocks and soil?

200

This step is when nitrates and nitrites (NO3 and NO2) are turned back in nitrogen gas (N2)

What is nitrification?

200

Excess phosphorus and nitrogen come from this human agricultural practice.

What is the use of artificial fertilizers?

300

This step of the water cycle is represented by number 4.

What is condensation?

300

Ocean exchange is the equilibrium of CO2 between these two locations. 

What are the atmosphere and the ocean?

300

During plant absorption, phosphate goes from here to here.

What is from the soil to the plant?

300

During nitrification, bacteria converts ammonia into these two things.

What are nitrates (NO3) and nitrites (NO2)?

300

If all humans started riding bikes to work and school, there would be a decrease in these steps of the carbon cycle.

What is atmospheric carbon and combustion?

400


This step of the water cycle is represented by number 2.

What is evaporation?

400


Letter "I" (as in iguana) represents this step of the carbon cycle.

What is decomposition?

400

Letters "I" and "N" represent this step of the phosphorus cycle.

What is decomposition?

400


Letter A represents this step of the nitrogen cycle.

What is nitrogen fixation?

400

Overuse of artificial fertilizers causes this

What are algal blooms (Eutrophication)?