Checkpoint Science Practice Test 2026 – All-In-One Guide to Master Your Exams!

The carbon cycle tracks how carbon moves between the air, living things, and Earth through processes that change carbon’s form. Photosynthesis pulls carbon dioxide from the atmosphere into plants, turning it into organic matter. Respiration then releases carbon back as CO2 when organisms use that carbon for energy. Feeding moves carbon along the food chain as organisms eat one another, transferring carbon-containing molecules up through ecosystems. Burning releases stored carbon back into the atmosphere quickly when fuels or biomass are combusted. These together capture the main ways carbon travels between air and living systems, including human-driven releases. While other processes like weathering and decay are also part of the broader cycle, this combination highlights the most direct transfers of carbon among living things and the atmosphere.