• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Nitrogen Cycle

Extracts from this document...

Introduction

Nitrogen Cycle Most nitrogen is found in the atmosphere. The nitrogen cycle is the process by which atmospheric nitrogen is converted to ammonia or nitrates. Nitrogen is essential to all living systems. To become a part of an organism, nitrogen must first be fixed or combined with oxygen or hydrogen. Nitrogen is removed from the atmosphere by lightening and nitrogen fixing bacteria. During electrical storms, large amounts of nitrogen are oxidized and united with water to produce an acid which is carried to the earth in rain producing nitrates. Nitrates are taken up by plants and are converted to proteins. Then the nitrogen passes through the food chain from plants to herbivores to carnivores. When plants and animals eventually die, the nitrogen compounds are broken down giving ammonia (ammonification). Some of the ammonia is taken up by the plants; some is dissolved in water or held in the soil where bacteria convert it to nitrates (nitrification). Nitrates may be stored in humus or leached from the soil and carried to lakes and streams. It may also be converted to free nitrogen (denitrification) and returned to the atmosphere. The nitrogen cycle is one of the most difficult of the cycles to learn, simply because there are so many important forms of nitrogen, and because organisms are responsible for each of the introversions. ...read more.

Middle

the nitrogen is returned to the soil. The usual form of nitrogen returned to the soil in animal wastes or in the output of the decomposers, is ammonia. Ammonia is rather toxic, but, fortunately there are nitrite bacteria in the soil and in the water which take up ammonia and convert it to nitrite, which is nitrogen with two oxygen's. Nitrite is also somewhat toxic, but another type of bacteria, nitrate bacteria, takes nitrite and converts it to nitrate, which can be taken up by plants to continue the cycle. We now have a cycle set up in the soil (or water), but what returns nitrogen to the air? It turns out that there are denitrifying bacteria which take the nitrate and combine the nitrogen back into nitrogen gas. Carbon Cycle The carbon cycle is relatively simple. From a biological perspective, the key events here are the complementary reactions of respiration and photosynthesis. Respiration takes carbohydrates and oxygen and combines them to produce carbon dioxide, water, and energy. Photosynthesis takes carbon dioxide and water and produces carbohydrates and oxygen. The outputs of respiration are the inputs of photosynthesis, and the outputs of photosynthesis are the inputs of respiration. ...read more.

Conclusion

This means that more carbon dioxide goes into the oceans, and more is present in the atmosphere. The latter condition causes global warming, because the carbon dioxide in the atmosphere allows more energy to reach the Earth from the sun than it allows escaping from the Earth into space. The concentration of carbon in living matter (18%) is almost 100 times greater than its concentration in the earth (0.19%). So living things extract carbon from their nonliving environment. For life to continue, this carbon must be recycled. That is our topic. Carbon exists in the nonliving environment as: * carbon dioxide (CO2) in the atmosphere and dissolved in water (forming HCO3-) * carbonate rocks (limestone and coral = CaCO3) * deposits of coal, petroleum, and natural gas derived from once-living things * dead organic matter, e.g., humus in the soil Carbon enters the biotic world through the action of autotrophs: * Primarily photoautotrophs, like plants and algae that use the energy of light to convert carbon dioxide to organic matter. * And to a small extent, chemoautotrophs - bacteria and archaeans that do the same but use the energy derived from an oxidation of molecules in their substrate. Carbon returns to the atmosphere and water by * respiration (as CO2) * burning * Decay (producing CO2 if oxygen is present, methane (CH4) if it is not. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Energy, Respiration & the Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Energy, Respiration & the Environment essays

  1. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    The net uptake of water occurs by osmosis. Osmosis is the passive transport of water across a semi permeable membrane. Because a plant cell has a wall, this affects Osmosis which occurs between the cell and its extra cellular fluid.

  2. Marked by a teacher

    The Role of the Respiratory and Circulatory Systems in the Provision of Oxygen and ...

    3 star(s)

    regulates the chemical signals that control the heartbeat (named SCN10A), was only discovered in 2010 by researchers at Imperial College (The Telegraph, 11 Jan 2010). Blood pressure must always be at a sufficient level to allow blood to reach all tissues that require it and the carotid sinus regulates this.

  1. The Pancreas is a large gland that forms part of the Endocrine System, but ...

    I can say this with a degree of confidence, as they would not incur the limitations that I did. They not only have more equipment then I did but it is better and they can even carry out more diagnostic tests then I can and even the data they can

  2. the effect of bile concentration on the activity of the enzyme lipase during the ...

    Obtain a thermometer and then put it into the conical flask with the milk inside 18. Put the conical flask with the milk inside in a water bath to keep the temperature constant 19. Take the 2cm3 pipette and suck 2cm3 of the sodium hydrogen carbonate solution and pour it into the conical flask 20.

  1. Investigate the effect of bile salt concentration on the digestion of milk by the ...

    the data and ignore any data points which are anomalous and which would affect the average. The raw data collected was a graph depicting the change in pH over a period of five minutes at differing bile salt concentrations. The graph started at an alkaline pH due to the carbonate ions.

  2. The effects and importance of the carbon and nitrogen cycle

    There is only a total of 20 amino acids all of which are characterised by the presence of nitrogen (or an amine group) which go on to make up thousands of different proteins or polypeptides which are linked chains of amino acids.

  1. formation, extraction and separation of the crude oil.

    2. We measured 5cm between the burner and the boiling tube. 3. We also measured 5cm� of water into the boiling tube. 4. Then we took the start of the temperature. 5. Then we lighted the burner and started the stop watch at the same time.

  2. What is a Plant?

    During daylight hours respiration continues, but photosynthesis also occurs. This is the opposite of respiration, and involves the synthesis of new carbohydrates from carbon dioxide and water. Photosynthesis is powered by the energy in sunlight, and some of this energy becomes trapped in the new carbohydrate molecules.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work