1. Photosynthesis
2. Respiration
3. Decay of organic matter
4. Volcanic action
Which of the above add carbon dioxide to the carbon cycle on Earth?
Explanation
The carbon cycle is a natural process that involves the movement of carbon between the atmosphere, oceans, soil, rocks, and living organisms. Respiration, decay of organic matter, volcanic action, fossil fuel combustion, deforestation, ocean-atmosphere exchange adds carbon to the cycle. All living organisms (plants, animals, and microorganisms) respire and breaking down glucose and oxygen to release energy, CO₂, and water. This process adds carbon dioxide to the atmosphere. When dead plants, animals, and other organic materials decompose microbes break them down. During decomposition CO₂ and methane (CH₄) are released into the atmosphere. Volcanic eruptions release stored carbon dioxide from the Earth’s mantle into the atmosphere. This is a natural source of CO₂ emissions. During photosynthesis plants, algae, and some bacteria absorb CO₂ from the atmosphere and use sunlight to convert it into glucose and oxygen. This process removes carbon dioxide from the atmosphere rather than adding it.