Which process primarily releases CO2 back to the atmosphere?

Which process primarily releases CO2 back to the atmosphere?

• A. Photosynthesis
• B. Respiration
• C. Biomass storage
• D. Condensation

Answer: (B)

Respiration releases CO2 back to the atmosphere. In cellular respiration, organisms break down sugars to get energy, and carbon atoms from those sugars are released as carbon dioxide. This happens in plants, animals, and microbes, so CO2 is constantly returned to the air as they respire. Photosynthesis does the opposite: it uses CO2 to make sugars, removing CO2 from the atmosphere. Biomass storage means carbon is held in living or dead material, which reduces CO2 in the air rather than releasing it. Condensation is a water cycle process unrelated to CO2 release. So the process that primarily releases CO2 is respiration.