Fossils, Early Organisms and the Atmosphere

• Fossils are the remnants of petrified organisms
• Fossils may have remained frozen for millions of years, or be insects preserved in resins such as amber
• Fossils can also be petrified impressions left by organisms
• Life originated on the planet some 4.5 billion years ago
• The first living organisms were bacteria, of which fossils exist dating from 3.8 billion years ago
• During the first two billion years, only prokaryotic bacteria lived on Earth
• The first eukaryotic cells existed some 2 billion years ago
• The first bacteria were anaerobic and dependent on the organic compounds that formed in the seas
• Fermentation is an example of anaerobic respiration
• The bacteria had no need of the oxygen, as they were all anaerobic, so it was released into the atmosphere as waste, which poisoned most of the bacteria, and those who survived left offspring
• Cyanobacteria were the first photosynthetic cells, also capable to fix nitrogen, as they use it to produce ammonia
• The atmosphere is a multi divided thin layer that protects against sunlight and radiation, and is essential for life on Earth
• All of the 8 planets have atmospheres, but they differ from Earth's, who has a more "special" atmosphere.
• The atmosphere is made up of a series of gases that surround Earth
• The Troposphere hosts the environment and weather, and it's thickness varies. Nitrogen and Oxygen are it's most abundant gases
• The Stratosphere hosts the ozone layer, which acts as a filter from the sun's radiation. The radiation is toxic to humans
• The Mesosphere is the coldest layer, and is where meteors burn. Aurora Borealis also occur on this layer
• The Thermosphere hosts satellites, and is where the International Space Station is located. This layer has the lightest air pressure
• The Exosphere is the outermost layer, and has no air. This is considered "open space"
• Oxygen caused the first major extinction
• Global Warming was much greater due to the amount of volcanoes and eruptions during the "Hot Earth" period
• The sky should be violet, but appears blue because sunlight emits more blue gamma rays than violet gamma rays, and human eyes are more perceptible to the blue light
• The atmosphere extends up to 6,200 kilometers
• Blood would start to boil reaching 60,000 feet
• Height changes pressure
• There is 40 trillion gallons of water in the sky
• Clouds are a visible mass of water vapor, formed from either liquid h2O or ice, and are responbile for rain
• Condensation nuclei are like cotton balls in which water molecules attach to until it gets too heavy and it rains
• The High level clouds are

  1. Cirrus
  2. Cirrocumulus
  3. Cirrostratus
• The Mid Level clouds are

  1. Altocumulus
  2. Nimbostratus
  3. Altostratus
• The Low Level clouds are

  1. Cumulus
  2. Stratocumulus
  3. Stratus
• Nitrogen fixation can occur naturally or artificially, and is essential to life because nitrogen compounds are neccesary in the formation of amino acids and proteins
• Nitrogen fixation is usually performed by soil microrganisms that convert nitrogen into ammonia, nitrites and nitrates
• Fossils can be located on the seabed, river, forest, in ice, or in a cave
• Fixation occurs when bacteria convert nitrogen gas (N2) into organic compounds that living organisms can take up
• Ammonification occurs when bacteria or fungi convert nitrogen gas (N2) or nitrogen compounds into ammonium ions (NH4+)
• Nitrification occurs when soil bacteria convert ammonium ions into nitrite ions (NO2-), then convert these to nitrate ions (NO3-)
• Denitrification occurs when soil bacteria convert nitrate ions (NO3-) into nitrogen gas (N2)
• Ammonification can also occur, when animal excretions and remains are converted by decomposers, ammonia (NH3) into ammonium ions
• Plants can absorb ammonium ions and nitrate ions through their roots