Atmosphere

• What is the composition of the Earth's atmosphere?

  About 80% nitrogen and 20% oxygen
• What role did volcanic activity play in the early atmosphere of Earth?

  It created a carbon dioxide-rich atmosphere
• What is the current understanding of the evolution of the Earth's atmosphere?

  It is considered a theory supported by evidence
• How did algae and plants affect the levels of carbon dioxide and oxygen in the atmosphere?

  They reduced carbon dioxide levels and increased oxygen levels
• How long has the Earth been evolving?

  About 4.6 billion years
• What was the state of the Earth during the first billion years of its history?

  The Earth was dry with intense volcanic activity
• What gases were produced by volcanic activity in the early atmosphere?

  Carbon dioxide, water vapor, nitrogen, methane, and ammonia
• What happened to the carbon dioxide as water vapor condensed into liquid water?

  It dissolved in the oceans and formed carbon precipitates
• When did algae begin to appear in Earth's history?

  About 2.7 billion years ago
• What process do algae and green plants use to produce oxygen?

  Photosynthesis
• What is the result of photosynthesis in terms of atmospheric gases?

  It takes in carbon dioxide and produces oxygen
• How did the evolution of algae and green plants impact the evolution of complex life forms?

  It allowed for the increase of oxygen levels, enabling complex life to evolve
• What happens to algae and green plants when they die?

  They fall to the seabed and become buried in sediment
• What do sedimentary rocks and fossil fuels form from over millions of years?

  Compressed layers of sediment from dead organisms
• What is coal primarily made from?

  Thick deposits of dead plant material
• What type of organisms mainly contribute to the formation of crude oil and natural gas?

  Dead plankton
• What is limestone primarily composed of?

  Calcium carbonate from marine organisms' shells
• What are the key processes that shaped the Earth's atmosphere?

  1. Volcanic activity produced carbon dioxide and other gases
  2. Water vapor condensed to form oceans, dissolving carbon dioxide
  3. Photosynthesis by algae and plants reduced carbon dioxide and increased oxygen
  4. Burial of organic material formed fossil fuels and sedimentary rocks
• What are the major changes in the Earth's atmosphere over its history?

  • Early atmosphere was rich in carbon dioxide due to volcanic activity
  • Oceans formed as water vapor condensed, dissolving carbon dioxide
  • Algae and green plants evolved, reducing carbon dioxide and increasing oxygen
  • Formation of sedimentary rocks and fossil fuels from dead organisms