Carbon Cycle

• How long has life on Earth existed?

  For billions of years
• Why has life on Earth been possible?

  Because it recycles everything
• What molecules are recycled on Earth?

  Water and carbon dioxide
• What can atoms be used for over time?

  To make different organisms
• How many atoms are estimated to be in a human body?

  Six octillion atoms
• Where have the atoms in your body been recycled from?

  Oceans, volcanoes, other animals, humans
• What are the two cycles covered in the study material?

  • Water cycle
  • Carbon cycle
• What is the first step in the water cycle?

  Energy from the sun causes evaporation
• What types of water can evaporate in the water cycle?

  Water from lakes, oceans, rivers, land
• What is transpiration in the water cycle?

  Evaporation of water from plant leaves
• What happens to water vapor as it accumulates in the sky?

  It condenses into clouds
• What is the term for water falling back to Earth?

  Precipitation
• After precipitation, where can the water go?

  Seep into soil, flow into rivers, taken up by plants
• What are the main components of the carbon cycle?

  • Carbon dioxide in the air
  • Carbon in plants
  • Carbon in soil
  • Carbon in fossil fuels
  • Carbon in animals
• What is the most important process in the carbon cycle?

  Photosynthesis
• What do plants and algae do during photosynthesis?

  They take in carbon dioxide and convert it
• What happens to carbon in plants after photosynthesis?

  It can be released by respiration or passed to animals
• What occurs when organisms die in the carbon cycle?

  They can decay or become fossil fuels
• What happens during microbial respiration of decayed organisms?

  Carbon is released as carbon dioxide
• What conditions lead to the formation of fossil fuels?

  Anaerobic conditions without oxygen
• How do humans contribute to the carbon cycle?

  By burning fossil fuels to produce carbon dioxide
• What is an additional process that can release carbon into the atmosphere?

  Burning of plants or biofuels
• What are the key points of the carbon cycle?

  • Carbon dioxide is absorbed by plants
  • Plants convert it into glucose
  • Animals consume plants and respire carbon dioxide
  • Decomposition releases carbon back into the atmosphere
  • Fossil fuels are formed from anaerobic decay
  • Burning fossil fuels releases carbon dioxide