Physical world

• The Atmosphere is composed of CO2, Water vapour, nitrogen, hydrogen and oxygen
• The atmosphere is in a state of dynamic equilibrium. The composition of the atmosphere is constantly changing due to natural processes and human activities.
• CO2 levels have decreased (form 72% to 0.04%) due to photosynthesis and dissolving in oceans to form carbonate rocks
• The atmosphere contains gases to make biological molecules used by living organisms. Carbohydrates, lipids and proteins contain carbon, oxygen and hydrogen
• Most UV light that passes through the upper atmosphere is prevented from reaching Earths surface by forms of oxygen in the stratosphere
• Oxygen can be monatomic, diatomic or triatomic
• The variations of oxygen form the ozone layer in the stratosphere. These gases absorb UV producing a dynamic equilibrium of chemical reactions which form and destroy ozone
• What are the major atmospheric gases?

  Nitrogen, Oxygen, Carbon dioxide, Argon
• What percentage of the atmosphere is nitrogen?

  79%
• What percentage of the atmosphere is oxygen?

  20%
• What percentage of the atmosphere is made up of other gases?

  1%
• What forms does nitrogen take after fixation?

  Ammonia (NH₃) and nitrates (NO₃⁻)
• What is the percentage of oxygen in the atmosphere?

  21%
• What is the main source of atmospheric oxygen?

  Photosynthesis in plants
• What is the role of carbon dioxide in photosynthesis?

  Enables plants to convert light into chemical energy
• What is the greenhouse effect?

  Regulates Earth's temperature
• What are the consequences of elevated CO₂ levels?

  Global warming and climate change
• What is the proportion of argon in the atmosphere?

  1. 93%
• What is the proportion of helium in the atmosphere?

  1. 000524%
• What is the significance of minor gases in the atmosphere?

  They contribute to atmospheric composition and stability
• What are the roles of minor atmospheric gases?

  • Argon: Inert, no biological function
  • Neon: Used in lighting and signage
  • Helium: Inert, used in weather balloons and cooling
• What is the likely effect of a 0.1% increase in atmospheric carbon dioxide levels?

  Increased disruptions to ecosystems and weather patterns
• Why do elevated CO₂ levels disrupt the greenhouse effect?

  They lead to global warming and climate change
• What are the roles of minor gases in the atmosphere?

  • Argon: Inert, no biological function (0.93%)
  • Neon: Used in lighting and signage (0.0018%)
  • Helium: Inert, used in weather balloons and cooling (0.000524%)
• What is the proportion of Argon in the atmosphere?

  1. 93%
• What is the role of Neon in the atmosphere?


  Used in lighting and signage
• What is the proportion of Helium in the atmosphere?

  1. 000524%
• What does it mean for gases to be inert?

  They do not react chemically with other substances
• How do greenhouse gases regulate temperature?

  They absorb and emit infrared radiation
• What happens when the Earth radiates heat?

  Greenhouse gases trap some heat
• What are the impacts of changes in atmospheric gas concentrations?

  They lead to global warming and climate change
• What are the categories and examples of impacts from gas changes on the environment?

  • Temperature Increase: Enhanced greenhouse effect (e.g., burning fossil fuels)
  • Sea Level Rise: Melting ice caps (e.g., global warming)
  • Weather Changes: Altered precipitation patterns (e.g., climate change)
  • Ecosystem Disruption: Shifted habitats (e.g., changing temperature)
  • Ocean Acidification: Increased CO₂ absorption (e.g., burning fossil fuels)
• How does deforestation impact atmospheric gas concentrations?

  It releases carbon dioxide into the atmosphere
• What environmental impacts does deforestation contribute to?

  Enhanced greenhouse effect and ecosystem disruptions