Module 1

• Water


  It is one of the important ingredients in the different biological processes. Absence of this will interfere reactions necessary for life. Solid form of this will also hinder living organisms to use it.
• Water on Earth


  • It has different forms - solid (ice) in the two poles and liquid along the equator which allows living organisms to consume it.
• Atmosphere


  It provides significant insulation or shielding from the sun and impact of small to medium size meteorites. Greenhouse gases like carbon dioxide (CO2) and methane (CH4) trap heat and protects our planet from freezing. Ozone (O3) layer shields the Earth's surface from harmful UV radiation. Atmosphere also provides chemicals needed for life, such as nitrogen and carbon dioxide.
• Factors affecting Earth's ability to hold atmosphere

  • Size of the planet
  • Distance from the sun
  • Presence of gravity
• Energy


  Earth has available energy-rich sunlight to support life. Living organisms like plants and photosynthetic bacteria use light as the source of their energy. Some chemosynthetic organisms rely on chemical energy to support various biological processes.
• Earth has been existing 4.543 billion years. In its early formation, life was not possible because the environment did not permit it. However, as time went by, life flourished from microorganisms into a more complex organism.
• The presence of life on Earth was made possible due to the following factors: temperature, water, atmosphere, and energy.
• Atmosphere


  • Provides significant insulation or shielding from the sun and impact of small to medium size meteorites
  • Greenhouse gases like carbon dioxide (CO2) and methane (CH4) trap heat and protects our planet from freezing
  • Ozone (O3) layer shields the Earth's surface from harmful UV radiation
  • Provides chemicals needed for life, such as nitrogen and carbon dioxide
• Size of the planet and its distance from the sun


  Affects its ability to hold significant amount of atmosphere
• Earth has a right size and distance from the sun that permits it to have a right amount of atmosphere
• The presence of gravity also helps in sustaining its atmosphere
• Energy


  • Earth has available energy-rich sunlight to support life
  • Living organisms like plants and photosynthetic bacteria use light as the source of their energy
  • Some chemosynthetic organisms rely on chemical energy to support various biological processes
• Earth is at right position from the sun that enables it to harness enough amount of sunlight
• Nutrients


  • Essential factor used to build and maintain organism's body structure
  • Insufficient or absence of nutrients can impede synthesis of the different biological molecules
• Nutrient recycling on Earth

  1. Water, carbon and oxygen, phosphate and nitrogen cycles

  2. Volcanism also helps in cycling the nutrients
• Low temperature slows down chemical reactions among living organisms
• Atmosphere provides chemicals needed for life
• Gravity does not affect the Earth's atmosphere
• Water traps heat from the sun
• Size and distance from the sun affect the planet's ability to hold atmosphere
• Absence of water interferes reactions necessary for life
• Earth cannot provide enough amount of sunlight as source of energy of most organisms
• Insufficient or absence of nutrients can hinder different biological processes
• Volcanism helps in nutrient recycling
• Atmosphere protects Earth from small to medium size meteorite impacts