6. How does lightning aid in nitrogen fixation? A. Lightning convert nitrogen gas to ammonium nitrate B. Lightning convert ammonia to ammonium ions C. Lightning splits nitrogen gas to combine oxygen to form nitrogen dioxide D. Lightning splits nitrogen gas to combine with nitrogen dioxide ! to form nitrates 4/12 7. Which nitrogen form is most used by plants? A. Ammonia C. Dinitrogen gas B. Nitrates D. Nitrites _8. All of the ff. are sulfur compounds present in the atmosphere except A Sulfate salts (SO,2) B. Hydrogen sulfide (H2S) C. Sulfur dioxide (SO2) D. Sulfur trioxide (SO,) 9. Which of the ff. cycles the slowest? C. Sulfur cycle D. Phosphorus cycle A. Carbon cycle B. Nitrogen cycle 10. What makes phosphoruS aycle differ from carbon, water and nitrogen cycle? A. Phosphorus cycles in the atmosphere while the other three do not B. Carbon, oxygen and water enters the atmosphere while phosphorus does not. C. Phosphorus do not change into different Usable forms D. Thore's no difference between these cycles. L 19 6. Phosphorus does NOT travol through which of the following spheres? C. Geosphere D. Biosphere A Atmosphere B. Hydrosphere 7 LWhich of the fR in/nro citroggg fixom2 .-

6 of 6 80% A. an increase in edge effect B. a decrease in the average temperature of the atmosphere C. an increase in biodiversity of the deforested areas 30. Which action by humans could improve the quality of the air? A. building homes that use only oil (fossil fuel) furnaces for heat B. buying cars that get more miles per gallon of gasoline C. increasing the number of coal-burming power plants that generate electricity D. cutting down forests to clear land for factories 31. Which action shows an increased understanding and concern by humans for nature? A. importing organisms that could become invasive to try stabilizing existing ecosystems B. getting rid of pollution control laws for industries that promote technology C. removing natural resources at a rate equal to the needs humans D. putting laws in place that regulate the number of animals hunted and killed each year 32. Ecosystems will have a greater chance of being stable over a long period of time if they have A. organisms…

2. Scientists study bubbles trapped in ancient glacial ice to determine how concentrations of nitrogen and carbon dioxide gas have changed over time. However, bubbles in glacial ice cannot provide information about changes in phosphorus. Explain why air samples are not useful for this purpose, and propose an alternative method to study how the amount of phosphorus in a region has changed over time.