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

"What is the significance of the nitrogen cycle in ecosystems? Using suitable examples, discuss the role of microorganisms in the Nitrogen Cycle. How can Man influence the Nitrogen Cycle?"

Extracts from this document...


"What is the significance of the nitrogen cycle in ecosystems? Using suitable examples, discuss the role of microorganisms in the Nitrogen Cycle. How can Man influence the Nitrogen Cycle?" Nitrogen makes up about 80 per cent of the Earth's atmosphere as a gas. However the gaseous molecule is very stable and has to be transformed before it can be used by most organisms as it is only available to them when it is ammonium or nitrate. It can only be removed from the atmosphere in two ways: by lightning and by nitrogen fixation. Only a few species can convert nitrogen by nitrogen fixation to biologically useful forms. Due to this, biologically useful nitrogen is often in short supply and can be the limiting factor in an ecosystem. There are five main steps in the Nitrogen cycle: Biological Nitrogen Fixation This is the conversion of gaseous nitrogen to ammonia using an enzyme called nitrogenase that only works in the absence of oxygen and requires large amounts of energy. ...read more.


The other method of nitrogen fixation is through lightning. The enormous energy of lightning breaks nitrogen molecules and enables their atoms to combine with oxygen in the air to form nitrogen oxides. These dissolve in rain, forming nitrates, that are carried to earth. Nitrification Nitrification is the conversion of ammonia to nitrate by soil bacteria. It is a two stage process. In the first stage Nitrosomonas utilise ammonia (NH ) as an energy source to oxidise it to nitrites ( NO ). In the second stage Nitrobacter oxidise the nitrites to nitrates (NO ). Both of these stages require oxygen and so must be performed in the presence of free oxygen. These two groups of autotrophic bacteria are called nitrifying bacteria. Plants take up the NO released by the bacteria and convert it to organic molecules such as amino acids. Assimilation This is the uptake of nitrite or ammonia by primary producers and its incorporation into proteins or nucleic acids. ...read more.


When a farmer plants a non-leguminous plant continuously on the same soil the nitrogen availability decreases. A way this is solved is by planting leguminous plants which enrich the soil by the root nodule bacteria releasing nitrogen. This can also benefit plants nearby as it increases the amount of nitrogen available in the area. Crop rotation involving periods of growing leguminous plants can be used to help improve the soil. This means farmers don't always need to use expensive and environmentally damaging synthetic nitrogen fertilisers. When used, often the nutrients from the fertilisers can be leached from the soil especially when they have been applied at the wrong time of year, just before heavy rain or in excessive quantities. This means the plants are unable to use the nutrients before they are leached from the soil. The excess fertiliser is carried away to adjacent water bodies where toxic cyanobacteria can increase due to the increase in nutrient levels. This can also lead to deoygenation of the water column due to the increased respiration or decomposition. This nutrient enrichment of natural water bodies as a result of pollution is called eutrophication. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Living Things in their 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 GCSE Living Things in their Environment essays

  1. Marked by a teacher

    Research question - Is using dogs for work ethical?

    5 star(s)

    So the natural response in the future would be to protect yourself. At the beginning of the conditioning someone throws a ball at someone else- originally an unconditioned stimulus. The ball heads toward the other person making them scream before it hits them.

  2. Investigating Seed Germination. Hypothesis If there is water, oxygen and a suitable ...

    Set up 4 shall receive 2cm3 of water per day. The volume of water will be measured using a 25cm3 syringe. --> Temperature of surroundings - The temperature of the surroundings must remain the same, as if the temperature changes, the activity of hydrolytic enzymes in the seed embryo will be affected, as enzymes are temperature-sensitive.

  1. Should cannabis be legalised in the UK?

    It seems to have been assumed for some years that only Indian hemp (then known as Cannabis indica) was of medicinal value. The fact that American and European hemp (Cannabis sativa) were capable of producing the same effects was not established until 1869, when Wood tried the extract of 1.5

  2. Discuss the important of bacteria in biogeochemical cycle

    CO2 is a trace gas in the earth's atmosphere that has a substantial effect on earth's heat balance by absorbing infrared radiation. This gas, like water vapor (H2O), CH4, and N2O, has a strong greenhouse effect. Life can alter the global concentration of CO2 over very short time periods.

  1. cellular respiration

    this stage the rate of respiration dramatically increases, the seed requires much more energy so the sprout can pierce through the shell and start growing. Aim: To determine whether germinating and non-germinating mung beans respire at different rates at different germination stages.

  2. An Investigation into the water quality of the River Banwell in

    Test site: 6 Reason for location: This location was picked so that if data was present at test site 4 and 5 I could see if the concentrations of pollutants had decreased. Test site: 7 Reason for location: There is another output, maybe from the local water pump.

  1. The role of constancy in the perception of illusion.

    The arrow with the outgoing fins, is e reverse of that idea. Perspective cues suggests it could be the inside corner of a room and that the outgoing fins are seen as walls approaching us, in which case the shaft looks to be further away from us.

  2. Scottish Seagrass Communities of the Genus Zostera

    They essentially inhabit the sub-littoral fringe, extending from 1-4m (depending on water clarity) below to just above low water of spring tides, and on sand or sandy mud firm substrate. Upper distribution is within the littoral zone is limited by susceptibility to desiccation, and lower limits set by light available for photosynthesis (Heeminga & Duarte 2000).

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