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In this module, we have learned that water, carbon, and the six macronutrients cycle around ecosystems. These elements become available to organisms in different ways, but once they are obtained by producers from the atmosphere or as ions dissolved in water, the elements cycle through trophic levels in similar ways. Consumers then obtain these elements by eating producers. Finally, decomposers absorb these elements from dead producers and consumers and their waste products. Through the process of decomposition, they convert the elements into forms that are once again available to producers. In the next module, we will explore how ecosystems respond to disturbances in these cycles.

Module 7 AP^® Review Questions

Question 1

1. Magnesium

2. Phosphorus

3. Sulfur

4. Nitrogen

5. Potassium

Question 2

1. increasing runoff.

2. increasing evaporation.

3. increasing percolation.

1. I only

2. I and II only

3. I and III only

4. II and III only

5. III only

Question 3

1. oceans.

2. the atmosphere.

3. sedimentary rock.

4. living organisms.

5. fossil fuels.

Question 4

1. is a limiting nutrient in many aquatic systems.

2. has an important gaseous phase.

3. is easily lost from soils due to leaching.

4. is often produced by volcanic eruptions.

5. changes chemical form often during its biogeochemical cycle.

Question 5

1. Potassium

2. Calcium

3. Carbon

4. Phosphorus

5. Sulfur

Question 6

1. Nitrogen fixation

2. Nitrification

3. Assimilation

4. Mineralization

5. Denitrification

Question 7

1. $100

2. $150

3. $200

4. $750

5. $1,000

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