Biochemichal Cycles

a) Carbon bonds are very strong and it is a common element on earth. because of this and its chemical makeup allow it to bond with a variety of other elements. Organic compounds usually contain Hydrogen and Oxygen. these are the kinds of compounds found in life such as plants and animals. Inorganic compounds are the opposite, these compounds generally don't contain either Fluorine or Hydrogen and are usually found in solids such as rocks. ex: Limestone. Carbon found in gas form has almost always bonded with oxygen or another gas, likewise water can bond with carbon to create carbonic acid. (1 )  The carbon cycle is necessary for all life on earth. Carbon Dioxide in the air can act as a pollutant causing climate change and also harming the conditions of life, becoming poisonous in large doses. plants however need some carbon dioxide to create photosynthesis. from this point animals eat the plants and through respiration release it back into the air and by either dying or excreting they also return it to the earth making it more fertile for plant life. (2)

b)  The Nitrogen cycle is very similar to the carbon cycle. nitrogen gets into the air through the burning of fossil fuels and through the excretion of animals. Once in the air it returns to earth either through nitrogen fixation in which microbes convert it to a form usable by plants or through rain that has collected nitrogen. once in the ground plants use it for nutrients and as animals eat the plants or breathe it enters their body where it resides until it is pooped out and returned to either the earth or the air. (3)

c) Carbon is necessary for both plants and animals to survive. because of its use as sustenance for plants and animals it is largely important to them. just like all other things too much is not healthy. excess of carbon is poisonous, small amounts are low in toxicity but they stay in ones body indefinitely. Nitrogen can have worse effects. nitrification of water sources can cause eutrophication and deplete the waters oxygen supply. because plants and animals need oxygen to survive they end up dead, and thus something healthy and even essential to life becomes disastrous to the ecosystem. (1)

1. http://en.wikipedia.org/wiki/Carbon#Occurrence, Carbon, Wikimedia foundation, John Wilhelm, November 7 2010.
2. http://www.windows2universe.org/earth/Water/co2_cycle.html, National Earth Science Teachers Association, NCAR, Roberta Johnson, November 7 2010.
3. http://www.visionlearning.com/library/module_viewer.php?mid=98,  The Nitrogen Cycle, John Arthur Harrison, Vision learning 2003.