The two main processes in the carbon cycle are photosynthesis and respiration. Photosynthesis occurs when plants, algae, and some bacteria convert carbon dioxide and sunlight into glucose and oxygen, effectively removing carbon from the atmosphere. Conversely, cellular respiration and decomposition release carbon back into the atmosphere as organisms break down organic matter for energy. This cycling of carbon between the atmosphere, biosphere, and geosphere is crucial for maintaining the planet's climate and supporting life, playing a vital role in ecosystem dynamics and energy flow.