Carbon Cycle

When humans burn fossil fuels, most of the carbon quickly enters the                       as carbon dioxide.

• Water
• Atmosphere
• Sun
• Air

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

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

How do living organisms return carbon to the atmosphere in the carbon cycle?

• respiration and photosynthesis
•  decomposition and respiration

In the carbon cycle, producers take in the gas __

• carbon dioxide
• oxygen
• nitrogen
• carbon monoxide

Which of the following removes carbon from the atmosphere?

• Combustion
• Respiration
• Photosynthesis
• Death

Organisms that do not decompose can be buried and become what?

• water
• nutrients
• air
• fossil fuels

If the plant population decreased, the amount of carbon would _________.

• Stay the same
• Increase
• Decrease

Which is a true statement?

• Humans depend on oxygen, plants depend on carbon dioxide

• Plants produce carbon dioxide

• Humans depend on carbon dioxide, plants depend on oxygen

• Humans don't depend on plants for the air they need

Combustion is another word for __________.

• Transportation
• Respiration
• Fossil Fuels
• Burning

Carbon can be found in...

• The atmosphere
• Soil
• Fossil fuels
• All of the above