Download Cycles of Materials

Cycles of Materials
In a self-sustaining ecosystem, various
materials are recycled between organisms
and the abiotic environment.
The recycling process allows materials to
be used over and over again.
Three major cycles are:
1. Carbon-hydrogen-oxygen cycle
2. Water cycle
3. Nitrogen cycle
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Carbon-hydrogen-oxygen cycle
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Carbon-hydrogen-oxygen cycle
Carbon, hydrogen, and oxygen are recycled
through the environment by the processes of
respiration and photosynthesis.
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Water Cycle
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Nitrogen Cycle
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Nitrogen Cycle
Nitrogen is needed by all living things because it is part of
the structure of amino acids and proteins.
In this cycle, nitrogenous wastes and the remains of dead
organisms are converted by decomposers and soil
bacteria into compounds that can be used by autotrophs.
The Nitrogen cycle includes the following reactions:
1. Atmospheric nitrogen is converted into nitrates by the
nitrogen-fixing bacteria.
2. Nitrates are used by plants for the synthesis of proteins.
3. Animals feed on plants and convert plant proteins to
animal proteins .
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4. Nitrogenous wastes and dead organisms are decomposed
and ammonia is released.
5. Ammonia is converted to nitrates by nitrifying bacteria.
6. Denitrifying bacteria break down nitrogen compounds and
release nitrogen gas into the atmosphere.
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