Questions on the nitrogen cycle and eutrophication from Exam 1 during the Spring 2015 section of EHF.

Exam Questions 9 and 10 on the nitrogen cycle:
9. Briefly define/describe the steps of the nitrogen cycle on the lines below. The first one is done for you to serve as an example. These steps are not presented in a particular order. (2 pts each)
A. nitrification Bacteria convert the ammonium ion (NH4+) to the nitrate ion (NO3-)
B. nitrogen fixation _____________________________________________________________
C. ammonification______________________________________________________________
D. denitrification ______________________________________________________________
10. Use labelled arrows (for example, use an arrow labelled “denitrification” that goes from one box to another) to add all the steps above into the diagram below to create a reasonable pathway that a nitrogen atom could follow from the atmosphere, through the ecosystem, and back to the atmosphere. You should involve the plant, the herbivore, decomposers, and soil bacteria of various kinds in this pathway. Make annotations and additions to the diagram as needed. Use your knowledge of the nitrogen cycle figure presented in lecture in this answer. (10 pts)
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Exam Question 12 on eutrophication
12. Explain the connections between farming, nutrient loading, algae blooms, aquatic decomposers, lake stratification, and water quality and fisheries problems in Lake Erie. Stated another way, explain the ecological interactions involved in the causes and consequences of eutrophication in Lake Erie. Be sure to use the chemical equation describing respiration in your answer. (15 pts)

Note: The scores of these two questions were compared using a paired t-test to measure differences in student learning for ecological material taught using the intensive case study method (eutrophication) vs. traditional methods only (nitrogen cycle)