Cycles and Succession

What process converts nitrogen gas into a biologically useful (fixed) form?

• Respiration

• Assimilation

• Denitrification

• Nitrogen fixation

Which organisms play the largest role in converting nitrogen into various usable forms and back to a gas form?

• rabbits

• bacteria

• plants

• worms

How do animals get nitrogen to make important biological molecules?

• Breathe it in through the air

• Fix it from nitrogen gas

• Consume other organisms

• Assimilate it through the soil

Which of the following cannot fix nitrogen?

• lightning

• fertilizer production

• combustion

• rain

What happens to carbon during the process of photosynthesis?

• CO₂ is released by plants

• CO₂ is taken up by plants

• organic carbon is taken up through plant roots

• carbon is lost through heat

The process of breathing in oxygen and releasing carbon dioxide into the air (or water) is...

• Assimilation

• Decomposition

• Photosynthesis

• Respiration

Which gas is most abundant in the atmosphere?

• carbon dioxide

• methane

• nitrous oxide

• nitrogen gas

Which of the following does NOT release carbon dioxide into the atmosphere?

• volcanic activity

• respiration

• photosynthesis

• fossil fuel combustion

Which of the following would not be included in the hydrosphere?

• ocean

• trees

• surface water

• groundwater

Which one of these does not add CO2 to the atmosphere?

• cooking with gas
• planting trees
• burning wood
• riding in a bus