The Carbon Cycle

Study Notes

The carbon cycle is the process by which carbon atoms are recycled between the Earth and the atmosphere, involving plants, animals, and various natural and industrial activities. Carbon is essential for life, regulating temperature, forming food, and providing energy.

• Carbon Cycle — the continuous movement of carbon among the Earth's atmosphere, oceans, and living organisms.
  Example: Carbon moves from the atmosphere to plants through photosynthesis and back through respiration.
• Photosynthesis — the process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen.
  Example: Plants absorb carbon dioxide from the air to make food.
• Respiration — the process by which organisms convert glucose and oxygen into energy, releasing carbon dioxide and water.
  Example: Animals and plants release carbon dioxide back into the atmosphere.
• Combustion — the process of burning fossil fuels, releasing carbon dioxide into the atmosphere.
  Example: Burning coal for energy increases atmospheric carbon dioxide.
• Decomposition — the breakdown of dead organisms, returning carbon to the soil and atmosphere.
  Example: Decomposing leaves release carbon back into the environment.

Exam Tips

Key Definitions to Remember

• Carbon Cycle
• Photosynthesis
• Respiration
• Combustion
• Decomposition

Common Confusions

• Confusing photosynthesis with respiration
• Thinking combustion only occurs naturally, not industrially

Typical Exam Questions

• What is the carbon cycle?
  The carbon cycle is the process of carbon moving between the Earth's atmosphere, oceans, and living organisms.
• How does photosynthesis contribute to the carbon cycle?
  Photosynthesis removes carbon dioxide from the atmosphere and incorporates it into plant biomass.
• What role does combustion play in the carbon cycle?
  Combustion releases stored carbon from fossil fuels back into the atmosphere as carbon dioxide.

What Examiners Usually Test

• Understanding of how carbon moves through different parts of the Earth
• The role of human activities in altering the carbon cycle
• The impact of deforestation and fossil fuel use on atmospheric carbon levels