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Cycles of Matter

Cycles of Matter. Chapter 2 Section 2. Recycling Matter. The way matter is recycled in ecosystems is similar to the way the metal in old cars is recycled. Like the supply of metal for building cars, the supply of matter in an ecosystem is limited .

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Cycles of Matter

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  1. Cycles of Matter Chapter 2 Section 2

  2. Recycling Matter • The way matter is recycled in ecosystems is similar to the way the metal in old cars is recycled. • Like the supply of metal for building cars, the supply of matter in an ecosystem is limited. • If matter could not be recycled, ecosystems would quickly run out of the raw materials necessary for life.

  3. Energy • Energy, on the other hand, is not recycled. • You must constantly supply a car with energy in the form of gasoline. • Ecosystems also must be constantly supplied with energy, in the form of sunlight. • Gasoline and the sun’s energy cannot be recycled. They must be constantly supplied.

  4. Energy and the Ecosystem • Energy enters an ecosystem from the producers to the consumers to the decomposers. • In contrast, matter cycles through an ecosystem over and over. • Matter in an ecosystem includes: water, oxygen, carbon, nitrogen and many other substances.

  5. The Water Cycle • Water is recycled through the water cycle. • The water cycle is the continuous process by which water moves from Earth’s surface to the atmosphere and back. • The process of evaporation, condensation, and precipitation make up the water cycle.

  6. Evaporation • The process by which molecules of liquid water absorb energy and change to the gas state is evaporation. • In the water cycle, liquid water evaporates from Earth’s surface and forms water vapor, a gas, in the atmosphere. • Most water evaporates from the surfaces of oceans and lakes. • The energy for evaporation comes from the sun.

  7. Condensation • As the water vapor rises higher in the atmosphere, it cools down. • When it cools to a certain temperature the vapor turns back into tiny drops of liquid water. • The process by which a gas changes to a liquid is called condensation. • The water droplets collect around particles of dust in the air, eventually forming clouds.

  8. Precipitation • As more water vapor condenses, the drops of water in the cloud grow larger and heavier. • Eventually the heavy drops fall back to the Earth in a form of precipitation – rain, snow, sleet, or hail. • Most precipitation falls back into oceans or lakes. • The precipitation that falls on land may soak into the soil and become groundwater. • Or the precipitation may run off the land, ultimately flowing into a river or ocean once again.

  9. The Carbon and Oxygen Cycle • Two other chemicals necessary for life are carbon and oxygen. • The processes by which they are recycled are linked together. • Carbon is the building block for the matter that makes up the bodies of living things. • It is present in the atmosphere in the gas carbon dioxide. • Producers take in carbon dioxide from the atmosphere during photosynthesis.

  10. Photosynthesis • In this process, the producers use carbon from the carbon dioxide to produce other carbon containing molecules. • These molecules include sugars and starches. • To obtain energy from these molecules, consumers break them down into simpler molecules. • Consumers release water and carbon dioxide as waste products.

  11. The Nitrogen Cycle • Like carbon, nitrogen is a necessary building block in the matter that makes up living things. • Since the air around you is about 78 percent nitrogen, you might think that it would be easy for living things to obtain nitrogen. • Most organisms cannot use the nitrogen in the air. • Nitrogen gas is called “free” nitrogen, meaning it is not combined with other kinds of atoms. • Most organisms can use nitrogen only once it has been “fixed” or combined with other elements to form nitrogen-containing compounds.

  12. Nitrogen Fixation • The process of changing free nitrogen gas into a usable form of nitrogen in called nitrogen fixation. • Most nitrogen fixation is performed by certain kinds of bacteria. • These bacteria live in buds called nodules on the roots of certain plants. • These plants, known as legumes, include clover, beans, peas, alfalfa, and peanuts.

  13. Legumes and Nitrogen • The relationship between the legumes and the bacteria is an example of mutualism. • Both the bacteria and the plant benefit from this relationship. • The bacteria feed on the plant’s sugars and plant is supplied with nitrogen in a usable form.

  14. Farmers • Many farmers make use of the nitrogen fixing bacteria in legumes to enrich their fields. • Every few years, a farmer may plant a legume such as alfalfa in a field. • The bacteria in the alfalfa roots build up a new supply of nitrogen compounds in the soil. • The following year, the new crops planted in the field benefit from the improved soil.

  15. Return of Nitrogen to the Environment • Once the nitrogen is fixed into chemical compounds, it can be used by organisms to build proteins and other complex substances. • Decomposers break down these complex compounds in animal wastes and in the bodies of dead organism. • This returns simple nitrogen compounds to the soil. • Nitrogen can cycle from the soil to producers and consumers many times. • At some point, bacteria break down the nitrogen compounds completely. • These bacteria release free nitrogen back into the air and the cycle starts again.

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