Understanding Earth's Cycles

What is the primary reason life on Earth has been sustained for billions of years?

• Constant supply of new atoms

• Recycling of molecules and atoms

• Presence of oxygen

• Stable climate conditions

Which process in the water cycle involves water vapor turning into clouds?

• Precipitation

• Condensation

• Transpiration

• Evaporation

Which process in the water cycle involves water moving from plants to the atmosphere?

• Condensation

• Transpiration

• Precipitation

• Evaporation

In the carbon cycle, where is carbon primarily stored?

• In plants as biological molecules

• In the ocean as salt

• In the soil as water

• In the atmosphere as oxygen

Which of the following is NOT a store of carbon in the carbon cycle?

• Atmosphere

• Plants

• Rivers

• Fossil fuels

What is the main role of photosynthesis in the carbon cycle?

• Breaking down glucose

• Producing oxygen

• Converting carbon dioxide into glucose

• Releasing carbon dioxide

What happens to carbon when plants and animals die?

• It is stored in the ocean

• It is broken down by microorganisms

• It is immediately released into the atmosphere

• It becomes part of the soil

How can carbon stored in fossil fuels return to the atmosphere?

• Through photosynthesis

• By being burned

• Via precipitation

• Through transpiration

What is the result of microbial respiration in the carbon cycle?

• Formation of fossil fuels

• Production of glucose

• Release of carbon dioxide

• Absorption of oxygen

What condition is necessary for the formation of fossil fuels from dead organisms?

• Presence of oxygen

• Anaerobic conditions

• Direct sunlight

• High temperatures