Question

How do humans cycle carbon from the biosphere to the atmosphere? (1 point)
• by driving cars that use gasoline for fuel
• by eating plants
• by respiration
• by planting vegetable crops

Answer 1

Humans cycle carbon from the biosphere to the atmosphere primarily **by respiration**. During respiration, humans (and other animals) inhale oxygen and exhale carbon dioxide, a process that releases carbon back into the atmosphere. While driving cars that use gasoline also contributes to carbon dioxide emissions, respiration is a direct biological process involved in the carbon cycle.