9.1 The composition and evolution of the Earth's atmosphere

• What are the major gases in the Earth's atmosphere today?

  Nitrogen and oxygen
• What percentage of atmospheric mass is contained in the troposphere?

  75%
• Which atmospheric layer reflects radio waves?

  Thermosphere
• Arrange the stages of atmospheric evolution in chronological order:

  1️⃣ Early Earth with nitrogen, carbon dioxide, and water vapor

  2️⃣ Emergence of photosynthesis leading to oxygen increase

  3️⃣ Oxygenation of the atmosphere

  4️⃣ Modern atmosphere with nitrogen and oxygen dominance
• In the early atmosphere, volcanic outgassing provided the gases necessary for a warm, protective environment
• Volcanic outgassing was the main source of nitrogen, carbon dioxide, and water vapor in the early atmosphere.


  True
• Which atmospheric layer contains most of the Earth's weather systems?

  Troposphere
• Nitrogen makes up approximately 78 percent of the Earth's atmosphere today.
• Photosynthesis converted carbon dioxide into oxygen, leading to the oxygen-rich modern atmosphere.


  True
• What processes balance carbon dioxide and oxygen levels in the modern atmosphere?

  Photosynthesis and respiration
• The Earth's atmosphere is held in place by gravity
• The ozone layer is located in the stratosphere
• Match the atmospheric layer with its key function:

  Troposphere ↔️ Most atmospheric processes

  Stratosphere ↔️ Absorbs UV radiation

  Mesosphere ↔️ Protects from space debris

  Thermosphere ↔️ Reflects radio waves

  Exosphere ↔️ Connects Earth to space
• What process balances photosynthesis in the carbon cycle?

  Respiration
• What primary role does volcanic activity play in shaping the Earth's atmosphere?

  Releases gases
• What is the primary influence of modern volcanic emissions on the atmosphere?

  Carbon cycle and weather
• Match the atmospheric layer with its key characteristic:

  Troposphere ↔️ Contains weather systems

  Stratosphere ↔️ Contains ozone layer

  Mesosphere ↔️ Meteors burn up here

  Thermosphere ↔️ High temperatures

  Exosphere ↔️ Outer layer of atmosphere
• What is the approximate percentage of oxygen in the Earth's atmosphere today?

  21%
• What are the primary gases released by volcanic eruptions?

  Water vapor, CO2, SO2
• Match the stage of atmospheric evolution with its key event:

  Early Earth ↔️ Volcanic outgassing

  Photosynthesis Emergence ↔️ Oxygen levels increase

  Great Oxygenation Event ↔️ Development of aerobic life

  Modern Atmosphere ↔️ Stable nitrogen and oxygen
• What are the major consequences of increased greenhouse gas concentrations?

  Climate change and pollution
• The Earth's atmosphere protects the planet from harmful radiation.

  True
• Meteors burn up in the mesosphere due to low air density.


  True
• The Earth's atmosphere provides carbon dioxide for photosynthesis
• Volcanic activity releases water vapor, carbon dioxide, and sulfur dioxide into the atmosphere.


  True
• The most abundant gas released by volcanoes is water vapor
• The Earth's atmosphere is held in place by gravity
• The stratosphere absorbs harmful UV radiation.


  True
• Order the stages of atmospheric composition over geological time:

  1️⃣ Early Earth: Nitrogen, carbon dioxide, water vapor

  2️⃣ Photosynthesis Emergence: Gradual increase in oxygen

  3️⃣ Oxygenation: Oxygen levels rise significantly

  4️⃣ Modern Atmosphere: Nitrogen and oxygen dominate
• The Great Oxygenation Event refers to the rise of oxygen levels due to photosynthesis.
• Burning fossil fuels releases carbon dioxide into the atmosphere, increasing greenhouse gas concentrations.


  True