1. Environmental Science Ch. 3.2; The cycling of materials

2. 1.What substance is the most essential to life? Water

3. 2. Describe the water cycle. Heat from the sun evaporates water from the earth‘s surface. As water cools in the atmosphere, it condenses and forms tiny droplets in clouds. When the clouds meet cold air, the water returns to the Earth again in the form of precipitation.

4. 3. What provides the energy that drives the water cycle? The sun

5. 4. What are some of the areas of the earth’s surface that water evaporates from? Oceans, lakes, rivers, moist soil, leaves of plants and bodies of organisms

6. 5. What are three forms of precipitation? Rain, sleet or snow

7. 6. Where does most precipitation fall? Why? The ocean, because oceans cover most of the earth’s surface.

8. 7. What three things can happen to precipitation that falls on the ground? 1) evaporates 2) collect in streams and rivers that flow into the ocean 3) soak into the soil

9. 8. Water that seeps down through the soil and rocks until it reaches a layer of rock or clay where it can go no farther is called what? Ground water

10. 9. Describe the carbon cycle. -Producers (usually plants) take in carbon dioxide from the atmosphere during photosynthesis. When consumers (usually animals) eat the producers, they get carbon.

11. Carbon cycle cont. As the consumers break down the food molecules during cellular respiration, the carbon is released back into the atmosphere as carbon dioxide.

12. 10. What is essentially stored carbon, left over from the bodies of plants and animals that died long ago and were trapped underground? Fossil fuels such as coal, oil and natural gas

13. 11. How are humans affecting the carbon cycle? We are adding more carbon dioxide to the atmosphere through the burning of fossil fuels than ever before.

14. 12. All organisms need nitrogen to build what? Proteins

15. 13. What percent of the atmosphere is nitrogen? 78%

16. 14. What do nitrogen fixing bacteria do? They take nitrogen gas from the air and transform (or “fix”) it into a form that plants can use.

17. 15. Where do nitrogen fixing bacteria live? Within the roots of a few plants, such as beans, peas, clover, and alder trees

18. 16. How do plants that don’t have nitrogen fixing bacteria in their roots get nitrogen? From the soil

19. 17. How do animals get nitrogen if they can’t breathe it through the air? From eating plants or other animals that contain it

20. 18. How do decomposers play a crucial part in the nitrogen cycle? They break down wastes and dead organisms, returning the nitrogen they contain to the soil in the form of ammonia. Other bacteria then transform it into nitrogen gas which returns it to the atmosphere.

21. 19. Describe the nitrogen cycle. Nitrogen fixing bacteria convert atmospheric nitrogen into ammonia which contains nitrogen in a form that plants can use. Plants are eaten by consumers which then absorb the nitrogen into their bodies.

22. Nitrogen cycle cont. Their wastes or remains are then decomposed returning the nitrogen to the soil as well as the atmosphere.

23. 20. Other substances besides water, carbon and nitrogen cycle through the earth’s processes. Some of these are sulfur, calcium and phosphorus.

24. 21. All organisms require phosphorus for growth and development.

25. 22. The phosphorus cycle has a short-term cycle and a long-term cycle. The short-term cycle involves plants obtaining phosphorus from the soil, then animals obtaining phosphorus from eating plants (or other animals that ate plants).

26. When these animals or plants die, they decompose and the phosphorus is returned to the soil to be used again. In the long-term cycle, phosphates washed into water become incorporated into rock as insoluble compounds.

27. Millions of years later, the rock containing phosphorus is exposed. As the rock erodes, the phosphorus again becomes part of the local flow of nutrients.