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life on earth - Coggle Diagram
life on earth
conditions for life on earth
-early conditions for life on earth:
-earth was formed around 4.6 billion years ago as gravity pulled rocks together to become a planet
-the huge amount of energy absorbed as the rocks were joined creating heat and producing a ball of molten rock
-the surface began to cool to produce the crust
-however volcanoes were erupting and releasing:
-steam
-CO2
-methane
-nitrogen
-CO2 was formed by the melting of carbonate rocks deep underground and virtually no oxygen existed
-as the earth cools the atmosphere began to stabilise
-mass:
-the mass of earth was great enough to prevent most gasses from escaping into space
-some gasses include (CO2, ammonia, and methane)
-atmospheric pressure and temp prevented all liquid water from being boiled
-water is important to living organisms for:
-temp regulation
-physiological solvent
-transport
-distance from the sun:
-suitable temperatures are maintained (goldilocks zone)
-being too close or to far from the sun would prevent liquid water from being present
-a suitable temp range was controlled by incoming insolation and its behaviour in the atmosphere
-this was controlled by the surface albedo, absorption of infrared energy and its presence in the atmosphere
-axis of rotation:
-the time taken for the earth to rotate on its axis produces a day / night cycle that is fast enough to minimise any excessive heating or cooling
-rotation of the earth and the tilt of the axis controls daily and seasonal variations in insolation and temperature
-speed of rotation:
-prevents over / under heating
-slow rotation = boiling
-fast rotation = freezing
-magnetic field:
-the earths molten core creates a magnetosphere that deflects solar radiation
-the gravitational attraction between the moon and earth creates tides and keeps the earths orbit nearly up right in relation to its movement
-life on earth:
-developed around 3.5 billion years ago and the conditions they were exposed to were very different to present day
-the atmosphere contained some toxic gasses such as ammonia but no oxygen
-the solar radiation reaching the ground contained high levels of UV radiation
how has life on earth brought about environmental change
-atmospheric oxygen:
-around 2.7 billion years ago, photosynthesising bacteria (cyanobacteria) began to produce oxygen
-surplus oxygen was released from the ocean into the atmosphere
-the increase in oxygen was detrimental to anaerobic organisms, but allowed more complex aerobic organisms to evolve
-carbon sequestriation:
-atmospheric CO2 levels were reduced by phototrophs
-CO2 is a greenhouse gas which helps retain heat energy within the atmosphere
-the sequestriation of CO2 prevented long term temp rises even though the brightness of the sun increases over billions of years
-biogeochemical cycles:
-as a greater diversity of organisms evolved interconnected biological processes developed, producing biogeochemical cycles
-this meant that small amounts of certain nutrients could support life over long periods of time, without resources being depleted
-the biogeochemical cycles are linked by living organisms, preventing the build up of waste products or shortages of resources
-eg, nitrogen and CO2 cycles
-transpiration:
-once plants had evolved and colonised on land, the process of transpiration returned water vapour to the atmosphere
-it helped to increase the amount of rainfall in certain areas
-this made to growth of more plant life possible (inland)