Water cycles embrace activities such as river flow, rain, and snow. Water continuously moves between the oceans, the atmosphere, and land--sometimes outside living organisms and sometimes inside them.
Water molecules usually enter the atmosphere as water vapor, a gas, when they evaporate from the ocean or other bodies of water. Cool water vapor carried by winds condense into tiny droplets that form clouds. When the droplets become large enough, they fall to the earth's surface as precipitation. Precipitation absorbed into the soil is called groundwater.
Water that re-enters the atmosphere through transpiration or evaporation begins the cycle anew.
Miller, Kenneth R., and Joseph S. Levine. "Chapter 3: The Biosphere." Miller & Levine Biology. Boston, MA: Pearson, 2010. N. pag. Print.
Carbon is an important element in life. It is responsible for the making of living tissues, and ecosystems, to an extent that life on Earth is often described as "carbon-based life."
In a carbon cycle, carbon moves through the biosphere by continuously exchanged between the atmosphere and oceans. Carbon often moves through physical and chemical processes that are taking place in the environment. Carbon dioxide (CO2) are taken in by plants during photosynthesis to be used for building carbohydrates. Carbohydrates can then be passed through food webs and food chains to consumers. CO2 is released into the atmosphere through decomposers, by human activities, and volcanic activity.
Miller, Kenneth R., and Joseph S. Levine. "Chapter 3: The Biosphere." Miller & Levine Biology. Boston, MA: Pearson, 2010. N. pag. Print.
Nitrogen is important to all organisms because it allows the creation of amino acids, which are used to build nucleic acids that form DNA, RNA, and proteins. Nitrogen is abundant in the biosphere that it occurs naturally. For the record, 78% of the Earth's atmosphere is made up of Nitrogen gas (N2). Thus, Nitrogen flows in the biosphere through what is called the nitrogen cycle.
In a nitrogen cycle, bacteria convert nitrogen gas into ammonia, in a process known as nitrogen fixation. Bacterias also convert nitrogen into nitrates and nitrites. These forms of nitrogen can then be consumed by the primary producers to form nucleic acids and proteins. Consumers, afterwards, consume these nitrogens to make their own nitrogen-containing compound. Other bacterias obtain energy by converting nitrates into nitrogen gas, which is released into the atmosphere in a process called denitrification. Humans also add nitrogen to the biosphere through the manufacture and use of fertilizers.
Miller, Kenneth R., and Joseph S. Levine. "Chapter 3: The Biosphere." Miller & Levine Biology. Boston, MA: Pearson, 2010. N. pag. Print.
Even though Phosphorous is essential in making vital molecules such as DNA and RNA, phosphorous is not abundant in the biosphere. For that reason, phosphorous does not enter the atmosphere in significant amounts. Instead, phosphorous in the form of inorganic phosphate remains mostly on land, in the form of phosphate rock and soil minerals, and in the ocean, as dissolved phosphate and phosphate sediments. Organic phosphate moves through the food web, from produces to consumers, and to the rest of the ecosystem.
Miller, Kenneth R., and Joseph S. Levine. "Chapter 3: The Biosphere." Miller & Levine Biology. Boston, MA: Pearson, 2010. N. pag. Print.