Cycles in Nature PowerPoint

Organisms are mainly composed of C, H, O & N
Living organisms also contain S and P as well as
several other elements
These elements compose the macromolecules
carbohydrates, lipids, proteins, and nucleic acids
The macromolecules and the elements that
compose them are constantly recycled as they
are passed from one organism to the next in a
food chain beginning with the autotrophs and
ending with decomposers
Cycles of matter that involve biological,
geological, and chemical processes
Biological – involves eating, breathing,
processing food, and eliminating waste
Geological – volcanic eruptions, formation and
breakdown of rock, and major movements within
and below the surface of the earth
Chemical – formation of clouds and precipitation,
the flow of running water, and lightning
Human activity – mining, burning fossil fuels and
wood, clearing land for building or farming, and
the manufacture and use of fertilizers affect the
cycles of matter on a global scale
Water continuously moves between the
oceans, atmosphere, and the land –
sometimes outside living organisms and
sometimes inside them
Water Vapor
Macromolecules such as carbohydrates,
lipids, proteins, and nucleic acids are
NUTRIENTS that organisms need to survive
There are specific element cycles for Carbon,
Nitrogen, and Phosphorus
Oxygen and Hydrogen do not have their own
cycles as they are combined with other
elements in the Water, Carbon, Nitrogen, and
Phosphorus cycles
Carbon is found in all four macromolecules:
Carbohydrates, Lipids, Proteins, and Nucleic Acids
Organic Compounds = Living Compounds
◦ Carbon-Based Life
◦ Fossil Fuels
Photosynthesis and Cellular Respiration
◦ Water + Carbon Dioxide + Sunlight = Oxygen + Glucose
◦ Glucose + Oxygen = Water + Carbon Dioxide + ATP
Nitrogen is found in the macromolecules
Proteins and Nucleic Acids
Nitrogen gas (N2) makes up 78% of the
◦ This Nitrogen is not in a form usable by organisms
◦ Nitrogen Fixation – rhizobacteria and mycorrhizae
 Convert nitrogen gas into ammonia (NH3)
 Other bacteria convert the ammonia to nitrites (NO2-)
and nitrates (NO3-) that are usable by autotrophs
◦ Denitrification – accomplished by bacteria
 Convert nitrates into nitrogen gas
NH3 or NH4+
(nitrogen fixing bacteria)
Atmospheric nitrogen is converted to ammonia or ammonium ion by nitrogen-fixing bacteria
that live in legume root nodules or in soil, or atmospheric nitrogen is converted to nitrogen
oxides by lightening.
NH3 or NH4+
(soil bacteria)
NO2- + H2O
Ammonia and Ammonium are oxidized by soil bacteria first to nitrite ions and then to nitrate
NH3 or NO3- or NO2
NO3- + 2H+
(denitrifying bacteria)
After plants have taken up nitrogen from the soil in the form of nitrate ions, the nitrogen is
passed along the food chain. When those plants and animals dies, bacteria and fungi take up
and use some of the nitrogen from the plant/animal protein and other nitrogen containing
molecules. The remaining nitrogen is released as ammonium ions or ammonia gas.
Denitrifying bacteria convert some ammonia, nitrite, and nitrate back to nitrogen gas, which
returns to the atmosphere.
N2 + 3H2
Heat + CH4 + H2O
CO + H2O
3H2 + CO
H2 + CO2
The phosphorus cycle does not have a
significant atmospheric component
Phosphorus remains mostly on land in the
form of phosphate rock and soil minerals and
in the ocean as dissolved phosphate and
phosphate sediment
Phosphorus is not as abundant as C, H, O, N,
and S
Phosphorus is found in the macromolecules
Lipids, Proteins, and Nucleic Acids

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