Nutrient Cycles

2. An example of a fossil fuel is ____.
4. Some of the phosphorus in soils can be washed away into water ___.
7. Another source of phosphorus in water comes from man-made ___.
8. phosphorus makes up important chemicals such as ___.
10. The cycle that has to do with the ocean is the ___ cycle.
12. Photosynthesis makes ___ and oxygen.
13. Animals use oxygen in the process of ___ to make more CO2.
14. The cycle that has to do with CO2 is the ___ cycle.
16. The cycle that has to do with rocks and minerals is the ___ cycle.
17. Too much phosphorus In water leads to plant ___, strangling all other life forms in the water.
19. Higher organisms use nitrogen to make their ___.

1. More CO2 is released in the atmosphere today than in the past because of the burning of ___.
3. Our ___ is 78% nitrogen gas.
5. In a part of the Nitrogen cycle, animals eat ___ containing nitrogen.
6. Another natural source for CO2 is ___.
7. plants use CO2 in the process of ___.
9. Too much CO2 in the atmosphere may be responsible for the ___ effect.
11. The cycle that has to do with gas in the atmosphere is the ___ cycle.
15. In the past, huge deposits of carbon were stored as dead plants and animals ___.
18. The ___ is the main regulator of CO2 in the atmosphere because CO2 dissolves easily in it.