Biodiversity
Biomes on Earth
India and Its Biodiversity
Indo-German Biodiversity
Elements of Nature
- Carbon cycle is an important gaseous cycle.
- Most of the carbon is stored as carbon dioxide, in either the atmosphere or dissolved in the ocean.
- The process of respiration and combustion makes carbon dioxide available to plants and trees for photosynthesis. The plants and trees, then release oxygen into the atmosphere.
- As animals feed on the plants, carbon becomes part of the energy system for ecosystems, as the carbon atoms travel through the food chains.
- Carbon in animals might stay in their bones, until the bone decays after the animal’s death, or might leave an animal’s body relatively quickly with waste matter.
- Some carbon in dead bodies of plants or animals becomes trapped and fossilised before decomposing is completed and can take form materials such as peat, coal or oil.
- The carbon cycle is important because all living things are made of carbon in one way or another. So it is very important that the carbon cycle functions well.
- The atmosphere of earth contains approximately 78% nitrogen.
- The nitrogen cycle is important due to its role as a basis for the production of nitrogen that is essential to all forms of life.
- Nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and DNA, the building blocks of all life.
- The nitrogen cycle is largely dependent on bacteria, fungi and blue-green algae, which convert the nitrogen from the air into nitrogen compounds.
- The conversion of atmospheric nitrogen into a form which is readily available to plants is called nitrogen fixation.
- The process of converting ammonia into nitrates is called nitrification.
- Plants take nitrogen from the soil in the form of nitrate salts or ammonium salts by absorption through their roots and use them to synthesise amino acids, proteins, nucleic acids, and other nitrogen compounds. This process is called nitrate assimilation.
- As animals feed on the plants, nitrogen becomes part of the energy system for ecosystems, as it travels through the food chains.
- Nitrogen is returned to circulation when the bodies of dead plants and animals disintegrate, and when animals excrete uric acid after breaking down proteins in their food. The excreted matter is eventually converted to nitrates after complex bacterial action.
- Nitrogen is commonly converted back into inorganic material when it joins the cycle through decomposition. The nitrogen is then typically changed into ammonium ion by bacteria and fungi through a process called mineralization.
- The process of conversion of organic nitrogenous compounds into ammonia is called ammonification.
- The conversion of nitrates in the soil to free molecular nitrogen is called denitrification. Extra nitrogen in the soil gets put back out into the air. There are special bacteria that perform this task as well.
- The water cycle is different from the other two cycles.
- Water exists in all three forms of matter: solid, liquid and gas.
- It can exist naturally at all of the temperatures, which occur on earth and can easily change from one form into another.
- Warmth from the sun causes water from oceans, lakes, streams, ice and soils to rise into the air and turn into water vapour (gas).
- The amount of water vapour in the air is called the relative humidity and for any given temperature there is a set amount of water that the air can hold.
- The warmer the air is, the more water it can hold.
- As water evaporates it moves upward on currents of warm air, until it reaches a temperature where the temperature is low enough that it cannot hold any more water.
- At this level the water vapour condenses and form clouds.
- Then water (in the form of rain, snow, hail or sleet) falls from clouds in the sky.
- Lakes or oceans are not the only sources from which water enters the air. Water evaporates from everything that is wet.
