B iogeochemical cycle 2
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Transcript of B iogeochemical cycle 2
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BIOGEOCHEMICAL CYCLE 2
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NITROGEN CYCLE
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NITROGEN Nitrogen is essential to living
things for the production of proteins and DNA which are used to pass on the hereditary information from parent to offspring.
Even though the atmosphere is about 78% nitrogen gas, plants and animals are unable to use nitrogen gas directly as a source of nitrogen to make organic nitrogen compounds.
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The nitrogen cycle can occur in both terrestrial and aquatic ecosystems.
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STEP 1: PLANTS CHANGE NITROGEN INTO….Path 1: Nitrogen Fixation by
Lightning The electrical energy of lighting
causes nitrogen gas (N2) to react with oxygen (O2) in the atmosphere to produce nitrate ions (NO3-) which reach the soil dissolved in precipitation.
Path 2: Nitrogen Fixation by Bacteria
Bacteria in the soil can change nitrogen gas (N2) into ammonia (NH3) which dissolves in water to form ammonium ions (NH4+)
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2.NITRIFICATION It is a bacterial process in which
ammonium (NH4) ions are converted into nitrate ions. They are first changed into nitrites (NO2-)
by bacteria, and then converted to Nitrates (NO3-) by a different group of bacteria.
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3: ASSIMILATION: THE MAKING OF PROTEINS FOR CONSUMER USE
Assimilation is the process by which plants use the nitrate ions (NO3-) to make amino acids, proteins, and DNA.
Only plants and bacteria can carry out the process, all other living organisms receive their nitrogen compounds from the food they eat.
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4. AMMONIFICATION Consumers generally produce wastes
throughout their lives. When consumers die their body contain nitrogen compounds such as protein and DNA.
Ammonification is when bacteria and some fungi break down these nitrogen compounds to make ammonia. The ammonia immediately dissolves in soil water to form ammonium ions.(NH4+)
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5.DENITRIFICATION During this step, nitrites are changes to
Nitrogen gas (N2) which returns to the atmosphere.
It is basically the reverse of nitrogen fixation and nitrification.
Done by bacteria!
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5.DENITRIFICATION During this step, nitrites are changes to
Nitrogen gas (N2) which returns to the atmosphere.
It is basically the reverse of nitrogen fixation and nitrification.
Done by bacteria!
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HUMAN IMPACT As a result of human
activities most ecosystems have been either totally destroyed or have components such as tropic structure, energy flow and chemical cycling disrupted.
Most effects are local or regional such as agriculture effects on nutrient cycling and introduction of toxic compounds in food chain.
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PHOSPHORUS CYCLE
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PHOSPHORUS CYCLE
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PHOSPHORUS CYCLE Phosphate is important for cell membranes, it helps
release energy that makes up DNA and calcium in bones.
Phosphate in rocks and fossils will weather (break down into tiny pieces). The inorganic phosphate dissolves in soil and
rivers. Plants absorb phosphates and consumers
receive phosphate from eating plants. Organic phosphate returns to the soil when
decomposition occurs. Bones, teeth and waste, as well as river runoffs
go to the ocean. Here the Phosphate is store until there is a
geological uplift.
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OXYGEN CYCLE
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NUTRIENT CYCLES Inorganic nutrients
(Carbon, Oxygen, Nitrogen) are recycled continually through ecosystems.
Plants and animals build structures from nutrients and inorganic material.
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ENERGY FLOW VS. NUTRIENT CYCLING Energy flows through ecosystems: it
enters the ecosystem via sunlight, is stored temporarily in complex molecules, and ultimately leaves in the form of heat.
Nutrients cycle within ecosystems: they are atoms that stay within the ecosystem and are found at different times in different pasrts of the system.
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NUTRIENT CYCLES Nutrients are recycled in a living
system. The key nutrients are carbon, hydrogen
Oxygen, Nitrogen and Phosphorus. These constitute 95% of all living matter
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HYDROGEN AND OXYGEN (WATER) CYCLE
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OXYGEN CYCLE
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OXYGEN The Earth's atmosphere contains
about 21% oxygen As you know from the previous lesson, oxygen gas (O2)
is recycled as part of the carbon, hydrogen, and oxygen cycles.
Oxygen gas is cycled between the atmosphere and the living organisms of both aquatic and terrestrial ecosystems.
Oxygen gas from the atmosphere is absorbed by the water in aquatic ecosystems.
Oxygen is also produced as a byproduct of the photosynthetic organisms that live in the aquatic ecosystems.
Heterotrophs (consumers) living in aquatic ecosystems require oxygen for cellular respiration but they receive their oxygen from the dissolved oxygen in the water
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OXYGEN During winter, ponds and
lakes may freeze.there is little or no light and
photosynthesis ceases. As a result, aquatic algae and plants
can no longer produce oxygen. Therefore it is possible that all fish within the lake or pond will die off. oxygen may be a limiting factor in
aquatic ecosystems However Oxygen is rarely, if ever, a
limiting factor in terrestrial ecosystems.