The 4 Cycles of Life

The 4 Cycles of Life

1. The Carbon Cycle

   • Natural process of circulation of Carbon between the atmosphere and all living things.
   • Forms 0.04% of the Earth's atmosphere
   • Green Plants use Carbon Dioxide to make sugars and Oxygen
   • The Carbon Cycle is the key mechanism by which energy from the sun is converted into chemical energy.
   • Decomposers release Carbon Dioxide when decomposing dead organisms.

2. The Phosphorous Cycle

   • Circulation of Phosphorous from rocks to living organisms and back again.
   • Phosphorous is a very reactive element, usually found in rocks.
   • The Phosphorous Cycle is way slower than all of the other cycles,
     • Phosphate compounds in rocks are released as the rocks weather.
       • Weathering is the breakdown of rocks by physical means and chemical means.
     • The Phosphate dissolve in water and are taken up by plants for nutrients.
       • When living organisms die, their phosphates are deposited back into the soil. Over very long periods, the soil forms rock and waits till erosion for the phosphate to get released.

3. The Water Cycle

   • The 3 main processes in Water Cycle are- Evaporation of Water, Condensation of Water vapour and finally precipitation.
     • Water exists in three states - Solid (ice), Liquid and Gas(Water Vapour).
   • The Water Cycle is driven by energy from the Sun.
     • Ice is less dense than water, which means that it floats on water.
   • Without the insulating layer offered by the ice surface, more and more of the ocean would freeze.

4. The Nitrogen Cycle

   • Most common gas in the air
     • Fixation is the process that makes Nitrogen available to all living Organisms.
   • Forms about 78% of the atmosphere
     • Forms about 3% of the human body
       • When Organisms die, the remains are broken down by decomposers, which release Nitrogen back to the atmosphere
   • Nitrogen cannot be directly absorbed by living things, it acts as its chemically inert.
     • Nitrogen is fixed in the atmosphere by lightning, biologically by some bacteria and industrially in human processes to make fertilisers.

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