4.10 Nitrogen Cycle

Key Points:
1. Nitrogen is the most abundant atmospheric gas and it isnt very reactive. Makes up around 78% of the atmosphere.
2. Nitrogen is very important for DNA and RNA
3. Nitrogen is present in amino acids, which make up protein which make up enzymes which convert, lets say, proteins into amino acids. Basically, if a producer, such as a plant, were to take nitrate ions from the soil and convert them into amino acids and form proteins and then form enzymes, when the primary consumer comes along and eats the plant, it will digest the amino acids and proteins inside the producer.

4.9 Carbon Cycle

Key Points:

 Photosynthesis. Co2 and H20 are combined in photosynthesis using chlorophyll and the light energy is trapped and is used to form organic molecules such as glucose

Carbon dioxide comes from the atmosphere, makes up 0.03% of the atmosphere. Photo synthesis is responsible for reducing the atmospheric CO2.

   
      Feeding. The food chain and the passage of carbon through the various trophic levels. The Producer -> Primary consumer, and in doing so the primary consumer takes the carbon from the producer and uses it to grow. Eaten by secondary consumer, and the carbon passes along the food chain

      At each stage in the chain, each form carries out respiration. 
     C6H12O6 + O2---enzymes---> energy and carbon dioxide. Respiration adds CO2 to the atmosphere.

      Producers respire sending out carbon dioxide sending out carbon dioxide to the atmosphere, therefore all organisms are putting CO2 to the atmosphere through the process of respiration

       
      Decomposition. All of the organisms in the food chain eventually will die, and organic molecules which remain are broken down by the decomposer organisms which include the bacteria and the fungi. And this results in the release of the carbon dioxide back to the atmosphere.

   
      Combustion. Fossil fuels (oils and coals)-> CO2 they are combusted. The best known examples are the industrial applications but also there is the motor vehicle such as cars, Lorries, airplanes which all combust fuel to release energy. Combustion can also occur in the environment such as the idea of lightening striking the vegetation causing fire, also forest fires and grassland fires. These are some of the stages of the carbon cycle.

      For an animation on the Carbon cycle go to this URL: http://www.biology.ualberta.ca/facilities/multimedia/uploads/alberta/CarbonCycle.html

    

       Images: 

Click for full size
Taken from 

http://oceancolor.gsfc.nasa.gov/SeaWiFS/LIVING_OCEAN/carbon_cycle.png

Click for full size
Taken from

http://www.gcsescience.com/Carbon-Cycle.gif

4.14 Enhanced Greenhouse effect

Key point:
The enhanced greenhouse effect is brought about my pollution, molecules such as CO2 H20 known as greenhouse gases, increase the concentration in the upper atmosphere and this causes the infra-red light would be remitted back to the surface, and this would raise the average global temperature. This is called global warming. An increase in the average temperature.
The consequences might include the melting of ice caps in the polar regions resulting in more water in the oceans, raised sea levels and this would change ocean currents and change winds and this start to contribute to the larger picture known as climate change. This would result in the redistribution of the worlds biomes, polar ice caps would melt, deserts would expand and distribution would change.

4.13 Greenhouse gases

Key points:
1. Human activity includes the burning of fossil fuels, and the emmisions such as carbon dioxide and nitrous oxide are created
2. They absorb infra-red light and redistribute it back to earth. The burning of fossil fuels from out factories and from vehicles, and perhaps from the burning of coals. Industrial, cars and domestic combustion.
3. Farming. Animals, such as cows emit methane gas for the process of digestion which is considered to be significant, around 9%, to greenhouse gases. Evaporation of water to form water vapour. Clouds are a significant contributer ot the greenhouse effect.
4. Refrigeration, solvents and propellents and CFCs. Chlorine carbon and flourine such as CCL3F.

4.12 Greenhouse Effect

Key points:
1. A represents UV light from the sun, short wavelength or high energy. B represents that about 50% of the light is reflected back out into outer space. C represents absorption on the earth's surface, where the UV light is converted into infra-red. D is when the infra-red light (long wave) being emitted back outwards.
2. F represents some of the greenhouse gases such as water vapour and CO2, and the infra-red hits the greenhouse gas and it will absorb this energy and it re-emits it in all directions, including downwards. So it remits infra-red but it redistributes with some of those waves hitting the surface raising the temperature a bit higher.
3. Enhanced greenhouse effect is where if the levels of greenhouse gases are increased, they will absorb more infra-red and deflect it back to the earth causing higher temperature and climate change.
4. CFCs, chlorofluorocarbons are well known for their effect of the ozone layer, some layers of gases O3

CCL3F ---> with sunlight ---> CCL2F- + CL-

The CL- catalyses the breakdown of O3 gases to O2, and this affects it because O3 is much better at absorbing UV Light than O2, and were effectively removing the protection of the ozone layer.

4.11 Gas Pollution

Key Points:
1. Sulphur dioxides formula is SO2, and sulphur dioxide as a gas is added to the atmosphere when we ahve the combustion of fossil fuels in factories. Such a coals and oils give off SO2. Also a significant contribution comes from vehicles and the combustion of oils and petrols and gas.
2. In the atmosphere SO2 combines with H2O and forms what is known as sulphuric acid. It is found within the water which condenses as clouds, and when it rains it is called acid rain. Acid rain affects plants and animals. Trees and plants are often burned by the direct effect. Top tree is often dead.
3. Another way is the root system, and the sulphuric acid causes calcium ions and magnesium to be leached out of the soil. This means the plant cant obtain it and suffers chlorosis.
4. The acid will form with rainwater to make streams, and then lakes and the acid reduces the pH and the effect of this brings about the effect of aluminium ions, and this affects fish. The aluminium causes a thickening of the mucous that lines the gills and reduces the fishes ability to take oxygen from water. The fish suffocates. Kills the fish. Acid frees aluminium ions which thicken the mucous which suffocates the fish. Effects of sulphur dioxide.
5. Carbon monoxide is produced when fossil fuels such as coal and gas are burned with insufficient oxygen, so we get CO. Carbon monoxide combines with haemoglobin inside the red blood cells and makes a molecule called carbinohaemoglobin, and the problem is that it blocks haemoglobin from carrying oxygen. Reducing the oxygen circulation, this is toxic and too much CO can be fatal.Very difficult to get the carbon monoxide off the haemoglobin.