Atmosphere

• What have scientists looked at to understand atmospheric changes?

  Evidence from rocks, air bubbles, and fossils
• How has our atmosphere changed over many years?

  It has evolved significantly over time
• What did volcanic gases release in the early atmosphere?

  Steam and CO₂
• What is the significance of the first billion years in atmospheric evolution?

  CO₂ was abundant in the atmosphere
• What did green plants produce during the next billion years?

  Oxygen
• What was the state of the atmosphere during the last billion years?

  It was mostly O₃
• What does the ozone layer allow for in terms of evolution?

  It allows for the evolution of complex animals
• What was the early atmosphere primarily composed of?

  Mostly CO₂ and water vapor
• What happened to water vapor in the atmosphere over time?

  It condensed to form oceans
• What gas was released by denitrifying bacteria?

  Nitrogen gas (N₂)
• How did nitrogen gas enter the atmosphere?

  Through denitrifying bacteria processes
• Why is nitrogen gas not very reactive?

  It has a stable molecular structure
• What effect did increasing nitrogen levels have on the atmosphere?

  It increased the amount of N₂ in the atmosphere
• What was the primary gas in the early atmosphere?

  Carbon dioxide (CO₂)
• What role did ammonia play in the atmosphere?

  It was formed through reactions with nitrogen
• How did the composition of the atmosphere change over time?

  From CO₂ and water vapor to O₂ and N₂
• What is the significance of the ozone layer in the atmosphere?

  It protects life from harmful UV radiation
• What is the relationship between atmospheric gases and life on Earth?

  Atmospheric gases support and sustain life
• How did the early Earth's surface conditions affect atmospheric composition?

  High volcanic activity released gases into the atmosphere
• What was the state of the atmosphere before the evolution of plants?

  It had very little oxygen
• What did the evolution of plants contribute to the atmosphere?

  Increased oxygen levels
• How did the presence of water vapor influence the early atmosphere?

  It contributed to the formation of oceans
• What is the primary function of the ozone layer?

  To absorb harmful UV radiation
• How did the evolution of complex animals relate to the ozone layer?

  The ozone layer allowed for their evolution
• What processes contributed to the formation of the current atmosphere?

  Volcanic activity, photosynthesis, and denitrification
• What gases were primarily released by volcanic activity?

  CO₂ and water vapor
• What is the significance of nitrogen in the atmosphere?

  It is a major component of the atmosphere
• How did the early atmosphere's composition affect life on Earth?

  It limited the types of life that could exist
• How is nitrogen (N₂) formed in the atmosphere?

  By ammonia reacting with oxygen
• Why is nitrogen (N₂) not very reactive?

  It is stable and does not easily react
• What happens to the amount of nitrogen in the atmosphere over time?

  It increases because it is being made
• What role do green plants play in the atmosphere?

  They photosynthesize and produce oxygen
• What do green plants remove from the atmosphere during photosynthesis?

  Carbon dioxide (CO₂)
• What do green plants produce during photosynthesis?

  Oxygen (O₂)
• How does the amount of oxygen in the air change over time?

  It gradually builds up due to plants
• What happens to carbon dioxide (CO₂) in the atmosphere over time?

  It gets locked up in fossil fuels
• What was the original composition of Earth's atmosphere mostly made of?

  Carbon dioxide (CO₂)
• How did the presence of oxygen in the atmosphere affect early organisms?

  It killed off organisms that couldn't tolerate it
• What did the presence of oxygen allow for in terms of evolution?

  It allowed more complex organisms to evolve
• What layer of ozone (O₃) was created by oxygen in the atmosphere?

  The ozone layer