Question

1. all biological molecules contain _?_. (carbon or carbon dioxide)
2. the combustion of coal, oil, and natural gas is part of the _?_. (nitrogen cycle or carbon cycle)
3. the development of a community on bare, exposed rock is an example of _?_. (primary succession or secondary succession)
4. the recovery of yellowstone national park following the fires of 1988 is an example of _?_. (primary succession or secondary succession)

Explanation:

1. Biological molecules are organic compounds, and all organic compounds contain carbon. Carbon dioxide is a non - organic molecule.
2. Coal, oil, and natural gas are fossil fuels. When they are combusted, carbon stored in them is released into the atmosphere as carbon dioxide, which is part of the carbon cycle. The nitrogen cycle involves the transformation of nitrogen - containing compounds.
3. Primary succession occurs on bare rock or other areas where no soil exists initially. Secondary succession occurs in areas where soil is already present.
4. After the 1988 fires in Yellowstone National Park, soil was still present. Secondary succession occurs in areas with existing soil, while primary succession starts on bare rock or areas with no soil.

Answer:

1. carbon
2. carbon cycle
3. primary succession
4. secondary succession