Carbon Cycle

oxygen is a gas produced by _ and used by  _ 

• plants and animals 
• photosynthesis and carbon dioxide 
• animals and plants 
• carbon dioxide and photosynthesis

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

Which process converts carbon in the form of sugar into carbon dioxide gas?

• Bioremediation
• Photosynthesis
• Respiration
• Transpiration

____________________ is a part of oceans, air, rocks, soil, and all living things.

• Nitrogen

• Water

• Carbon

• Silver

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

• Water
• Atmosphere
• Sun
• Air

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

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

• Stay the same
• Increase
• Decrease

What is happening at 1?

• respiration: releasing CO₂
• decomposing CO₂ in the soil
• photosynthesis: absorbing CO₂
• turning CO₂ from the atmosphere into organic molecules