Earth science grade 11

• Earth has existed for 4.543 billion years
• During its early formation, life is not possible because the environment does not permit it
• As time goes by, microorganisms formed into more complex organisms
• Life on earth is possible due to the following factors: Temperature, Water, Atmosphere, Energy, Nutrients
• Temperature


  • Influences how quickly atoms, molecules, or organisms move
  • Low temperature: slows down chemical reactions, produces ice
  • High temperature: break down of important biological molecules
  • Radiogenic heat: heat emitted by the planet
  • Goldilocks' zone - Earth's location where the temperature is just right
• Earth is the only planet with liquid water because some planets may have water but due to the low temperature it's only in solid form
• Water


  • Most important ingredient in biological processes
  • Absence of water will interfere with reactions necessary for life
  • Solid form (ice) hinders living organisms to use it
  • Solid (ice) in the 2 poles and liquid along the equator. (can be consumed.)
• Atmosphere


  • Provides chemicals needed for life: carbon dioxide, nitrogen
  • Provides insulation/shielding from the sun and impact of small to medium size meteorites
  • Greenhouse gases like carbon dioxide (CO2) and methane (CH4) traps heat and avoid our planet from freezing
  • The Ozone (03) layer shields the Earth's surface from harmful UV radiation
  • Size and distance from the sun affects the ability of the Earth to hold a significant amount of atmosphere
  • Presence of gravity also sustains the atmosphere
• Energy


  • Earth has rich sunlight to support life
  • Living organisms like plants and photosynthetic bacteria use light as a source of energy
  • Chemosynthetic organisms rely on chemical energy to support biological processes
  • Earth's position from the sun is just right to enable it to harness enough amount of sunlight
• Nutrients

  • Essential factor used to build and maintain organism's body structure
  • Insufficient amount can impede synthesis of biological molecules
  • Volcanism helps in cycling nutrients
  • Water, carbon, and oxygen are some examples of nutrients
• 4 Sub Systems of the Earth

  • Atmosphere
  • Geosphere
  • Hydrosphere
  • Biosphere
• Atmosphere


  Comes from the Greek roots atmos - gas and sphaira globe or ball, makes up of all the gases on Earth
• Atmosphere


  Extends outward about 10 000 km from the surface of the Earth
• Layers of the atmosphere

  • Exosphere
  • Thermosphere
  • Mesosphere
  • Stratosphere
  • Troposphere
• Exosphere


  • Farthest layer, extends to about 10 000 km above the Earth's surface
• Thermosphere

  • Found 85 to 600 km above the Earth's surface, has charged particles affected by the Earth's magnetic field
• Mesosphere

  • Extends from 50 to 85 km above the Earth's surface, protects the Earth from the impact of space debris
• Stratosphere


  • Found 14.5 to 50 km above the Earth's surface, contains the ozone layer that protects the Earth from the Sun's harmful UV radiation
• Troposphere

  • Extends to about 14.5 km above the Earth's surface, where weather forms
• Geosphere

  Includes all the soil, rocks, and minerals present in the crust to the core of the Earth
• Layers of the geosphere

  • Crust
  • Mantle
  • Outer Core
• Crust

  • Outermost layer of the geosphere, made mostly of silicate materials, two types: oceanic and continental
• Mantle

  • Made mostly of silicate rocks rich in magnesium and iron, about 2900 km thick, with increasing temperatures at increasing depths
• Core


  • Innermost layer of the Earth, has a radius of 3400 km, made out of iron and nickel
• Hydrosphere

  Composed of all the water on Earth in any form: water vapor, liquid water, and ice
• Hydrosphere includes all bodies of water such as oceans, lakes, rivers, and marshes
• Clouds and rain are also part of the hydrosphere
• Water on Earth is constantly moving, through the oceans in currents, with warm waters in the tropics moving toward the poles and cold water from the polar regions moving toward the tropics
• Biosphere


  Comprised of all living things, organisms interact with the other spheres to survive
• Many organisms need oxygen and carbon dioxide from the atmosphere, and water from the hydrosphere, to carry out life processes
• Rocks, soil, and minerals from the geosphere also support life
• Matter and energy move and cycle between the four different subsystems (atmosphere, geosphere, hydrosphere, biosphere), making life on Earth possible
• An example of these cycles is the water cycle, where water moves between the different spheres, absorbing, releasing, and transporting energy around the world in its different forms
• If matter or energy does not change from one form to another, such as water vapor not falling back to Earth as rain, then the bodies of water will be drained and no life on Earth will exist
• The soil can be considered as part of the hydrosphere, geosphere, and biosphere, as it is a complex material made up of air, soil particles, water, and organisms
• The habitable zone is referred to as the Goldilocks' zone
• The Earth's temperature impacts chemical and biological processes
• If Earth is the first planet from the sun, the most likely outcome is no atmosphere and no liquid water
• The atmosphere acts as the Earth's blanket
• The hydrosphere includes salt water from the oceans and seas