Carbon Cycle - SS2 Biology Lesson Note
The carbon cycle refers to the natural process through which carbon is exchanged between the atmosphere, oceans, land, and living organisms. It plays a crucial role in regulating Earth's climate and maintaining a balance of carbon dioxide (CO2) in the atmosphere.
The carbon cycle involves several interconnected processes:
1. Carbon Fixation: Green plants and other photosynthetic organisms capture carbon dioxide from the atmosphere during photosynthesis. They convert it into organic compounds, primarily glucose, which can be used as an energy source.
2. Respiration: Organisms, including plants, animals, and microorganisms, release carbon dioxide into the atmosphere as a byproduct of cellular respiration. This process occurs when organic compounds are broken down to release energy.
3. Decomposition: When living organisms die, their bodies undergo decomposition. Decomposers, such as bacteria and fungi, break down organic matter, releasing carbon dioxide back into the atmosphere.
4. Combustion: When organic matter (such as wood or fossil fuels) is burned, carbon is rapidly released into the atmosphere as carbon dioxide. Combustion processes, including natural wildfires and human activities like burning fossil fuels, contribute to the increase in atmospheric carbon dioxide levels.
5. Exchange with the Oceans: Carbon dioxide from the atmosphere can dissolve into the surface waters of the oceans. This dissolved carbon can be taken up by marine organisms through photosynthesis. Additionally, carbon dioxide can be released back into the atmosphere through oceanic respiration and outgassing.
6. Sedimentation and Fossilization: Over long periods, carbon-containing materials can be buried in sediments, forming sedimentary rocks. These rocks can store carbon for millions of years. Fossilization of ancient plants and animals also locks away carbon in the form of fossil fuels, such as coal, oil, and natural gas.
Human activities, particularly the burning of fossil fuels, have significantly disrupted the carbon cycle. The increased release of carbon dioxide from burning fossil fuels has contributed to the enhanced greenhouse effect, leading to global warming and climate change.
