Carbon is an element that is present in all living things, and is a part of carbohydrates, proteins, and fats. It is constantly recycled on our planet, moving from the atmosphere to living things and back to the atmosphere as carbon dioxide. Carbon can also be passed between living things when one organism eats another. Known as the Carbon Cycle, this recycling process is composed of a number of steps that cycle carbon through the biosphere, atmosphere, hydrosphere, and geosphere.
Fossil fuels are nonrenewable fuels formed from the remains of living organisms formed over millions of years.
The process used by green plants to create glucose from carbon dioxide and water using sunlight is photosynthesis. The equation for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2
A chemical reaction used by living things to release energy from glucose is called respiration; it can be aerobic or anaerobic. The equation for aerobic respiration is C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy)
Combustion is a chemical reaction involving oxygen and a fuel, also known as burning. The word equation for combustion is fuel + oxygen → carbon dioxide + water
The breaking down of organic material by other organisms is decomposition. It is also known as decay.