Pre-test: Carbon & Nitrogen Cycle

Fossil fuels are part of which of the following cycles?

• hydrologic

• carbon

• nitrogen

• phosphorus

What happens during the process of nitrogen fixation?

• Bacteria change ammonium into nitrate

• Bacteria grow on nodules on plant roots

• Bacteria absorb ammonia and excrete ammonium

• Bacteria convert gaseous nitrogen into ammonia

What does the diagram show?

• the nitrogen cycle

• the water cycle

• the oxygen cycle

• the carbon cycle

Which organisms help convert gaseous nitrogen into ammonia in the nitrogen cycle?

• bacteria

• trees

• squirrels

• grasses

Which of the following is not a naturally-occurring disruption of biogeochemical cycles?

• a large herd of sheep

• volcanic erpution

• a river floods its banks

• a forest fire

Bacteria are important in the nitrogen cycle because they

• help convert nitrogen into a form that organisms can use

• respire, returning carbon dioxide into the atmosphere

• decay and eventually form fossil fuels

• produce sugars that plants can use