Carbon cycle and Nitrogen cycle

Carbon Cycle

carbon cycle

  • The carbon cycle gives us an idea as what causes carbon dioxides to increase or decrease in the environment.
  • There are two aspects involved in this cycle, namely the removal of carbon dioxide from the atmosphere and the addition of carbon dioxide to the atmosphere which takes place.
  • The air contains about 0.04% of carbon dioxide.
  • Carbon dioxide by plant for the process of photosynthesis to form starch molecules.
  • When the plants are eaten by animals, the same carbon becomes a constituent of organic molecule in their body.
  • When plants and animals respire carbon dioxide is released back into the atmosphere.
  • Plants and animals dies decomposers decompose them.
  • Dead plants and animals then change into fossil fuels and when they are burnt carbon dioxide is released into air.

Importance of carbon cycle

The carbon cycle is important because all living things are made of carbon in one way or another. The carbon cycle is how carbon is exchanged throughout the earth: between the atmosphere, oceans, ecosystem and geosphere. This helps to balance the amount of carbon dioxide level in the atmosphere preventing from global warming.

Nitrogen Cycle

nitrogen cycle

  • Living organisms neednitrogen to make proteins. Nitrogen gas forms 4/5 of the atmosphere
  • They cannot get it directly from the air because nitrogen gas is too stable to react inside an organism to make new compounds. Nitrogen must be changed into a more reactive form to allow plants and animals to use it.
  • Plants can take up and use nitrogen when it is in the form ofnitrates or ammonium salts. Nitrogen fixation is the process when it is changed into a more reactive substance.
  • There are two main ways that nitrogen fixation takes place in the environment.
    • By nitrogen-fixing bacteria
      Some plants (legumes such as peas, beans and clover) have roots with nodules that contain these bacteria, so the plant receives a direct source of nitrates. A special type of bacteria called nitrogen fixing bacteria take in atmospheric nitrogen and produce ammonia(NH3).
    • By lightning

During lightning, at very high temperature the Nitrogen in the atmosphere combines with oxygen and form oxides of Nitrogen. These oxides dissolve in water vapor and form dilute acids of nitrogen. These acids reach the soil by rain and react with other chemicals in the soil and form nitrates.

  • When organisms die, decomposers (such as bacteria and fungi) consume the organic matter and lead to the process of decomposition. During this process, a significant amount of the nitrogen contained within the dead organism is converted to ammonium.
  • The conversion of Ammonium compounds into nitrates is called Nitrification. In this process Ammonium compounds are oxidized to Nitrites by Nitrite bacteria and nitrites are oxidized to nitrates by Nitrate bacteria.
  • A few of these types of bacteria return nitrogen to the atmosphere by a process called denitrification, however this amount is small. Anaerobic bacteria such as Pseudomonas denitrificans living in the water logged soil break down nitrates in the soil into Nitrogen and oxides of Nitrogen which cannot be absorbed by plants.


Importance of nitrogen cycle

Nitrogen is essential part of the biological molecules such as protein and nucleic acid, which makes nitrogen essential for all living organisms. Human body does not use the nitrogen that you inhale with each breath. But, like all living things, your body needs nitrogen. Your body gets the nitrogen it needs to grow from food. Most plants get the nitrogen they need from soil. Many farmers use fertilizers to add nitrogen to the soil to help plants grow larger and faster.