Exploring the Carbon Cycle in Biological Systems

What element forms the backbone of important biological molecules like glucose and DNA?

• Carbon

• Hydrogen

• Nitrogen

• Oxygen

What percentage of the human body is made up of carbon by mass?

• 5-10%

• 18-19%

• 25-30%

• 40-45%

What is the primary form of carbon in the atmosphere?

• Carbon monoxide

• Calcium carbonate

• Methane

• Carbon dioxide

What percentage of Earth's atmosphere is carbon dioxide?

• 1%

• 78%

• 21%

• 0.04%

Which process do plants use to fix carbon from the atmosphere?

• Respiration

• Combustion

• Photosynthesis

• Fermentation

How do autotrophs contribute to the carbon cycle?

• By consuming other organisms

• By breaking down organic matter in the soil

• By releasing carbon dioxide through respiration

• By fixing carbon dioxide from the atmosphere

What happens to the carbon in plants when they are consumed by animals?

• It is transformed into oxygen.

• It is released back into the atmosphere as CO2.

• It is used to form animal proteins.

• It is expelled as waste.

What is formed from carbon dioxide being absorbed into the ocean and used by living things?

• Plastic

• Methane

• Limestone

• Fossil fuels

What role does the ocean play in the carbon cycle?

• It prevents carbon dioxide from entering the atmosphere.

• It converts carbon dioxide directly into oxygen.

• It absorbs carbon dioxide and forms carbonate.

• It releases carbon dioxide into the atmosphere.

What happens to carbon when fossil fuels are burned?

• It is permanently removed from the carbon cycle.

• It forms new organic compounds.

• It is released back into the atmosphere as carbon dioxide.

• It is converted into solid carbon.