Biogeochemical Cycles:
The Flow of Matter
LS2.2
•Create a model tracking carbon atoms
between inorganic and organic molecules in
an ecosystem. Explain human impacts on
climate based on this model.
LS2.3
• Analyze through research the cycling of
matter in our biosphere and explain how
biogeochemical cycles are critical for
ecosystem function.
Biotic and Abiotic Factors
•Biotic factors: Living factors of the
environment
• Examples: animals, plants, fungi, bacteria, protists
•Abiotic factors: the nonliving parts of an
environment.
• Examples temperature, moisture, light, and soil.
2
ENERGY & MATTER
Energy flows through the ecosystem in one
direction and then gets used up.
But…other materials move through the
ecosystem too.
Atoms are never destroyed . . . Only
transformed.
Take a deep breath.
The atoms you just inhaled may
have been inhaled by a dinosaur
millions of years ago.
Four different elements (atoms) make up
95% of the body in most organisms
The same molecules are passed around
again and again within the biosphere (Earth’s
atmosphere) in Biogeochemical Cycles.
Biogeochemical Cycles
– Materials are recycled between the biotic and
abiotic environment.
– The same materials can be reused.
Examples of Cycles:
•
•
•
•
Carbon
Nitrogen
Phosphorus
Water
Carbon Cycle
Why is carbon important?
Found in all the building blocks of cells:
• carbohydrates, proteins, nucleic acids, lipids
CHO
CHON
CHONP
CHO
Carbon Cycle
Why is carbon important?
Carbon in CO2 provides the atoms for glucose
production during photosynthesis…
• glucose is the fuel that all living things depend on.
Carbon Cycle
Why is carbon important?
ALL living things break down carbohydrates during
cellular respiration (releasing CO2 & water)
Decomposers release CO2 into the atmosphere when
they break down organic molecules
4 main CARBON Reservoirs (storage):
1.In the atmosphere as CO2 gas
2.In ocean as dissolved CO2 gas
3.On land in organisms, rocks, soil
4.Underground as coal & petroleum (fossil fuels) and
calcium carbonate in rocks
CO2 in
atmosphere
CO2 in
Ocean
BIOLOGY; Miller and Levine; Prentice Hall; 2006
Where does CO2 in atmosphere come from?
1.Volcanic Activity
2.Human Activity
(burning fossil fuels,
deforestation etc.)
3.Cellular respiration
4.Decomposition of
dead organisms
CO2 in
atmosphere
CO2 in
Ocean
BIOLOGY; Miller and Levine; Prentice Hall; 2006
Human Impacts on the carbon cycle
• Greenhouse Gases – gases in the Earth’s
atmosphere that trap heat.
– They let sunlight pass through the atmosphere,
but they prevent the heat that the sunlight brings
from leaving the atmosphere.
• The main greenhouse gases are:
– Water vapor (H2O)
– Carbon dioxide (CO2)
Human Impacts on the carbon cycle
1. Fossil Fuel burning – releases CO2 to the
atmosphere.
– Examples: coal, oil
2. Human-driven changes in land use and land
cover:
– Deforestation (logging, clearing, burning trees)
– Urbanization
– shifts in vegetation patterns
Human Impacts on the carbon cycle
3. Increased biomass – human population is
growing exponentially
– more people doing cellular respiration (output is CO2)
Human Impacts on the carbon cycle
4. Ice caps melting – releases CO2
5. Oceans warming  less phytoplankton
(autotroph) less photosynthesis (less CO2
removed from atmosphere, less O2 for other
life.)
Human Impacts on Climate
(and the carbon cycle)
Why does this matter and what can we do???
1. Research how these human activities impact
climate change.
We know we are affecting the carbon cycle, but what is this
doing to earth’s climate?
2. Based on the human activities we talked
about, what can humans do to reduce (or even
reverse) these affects on climate change?
Biogeochemical Cycles:
The Flow of Matter
LS2.3
• Analyze through research the
cycling of matter in our
biosphere and explain how
biogeochemical cycles are
critical for ecosystem function.
Biogeochemical Cycles
– Remember, materials are recycled between the
biotic and abiotic environment.
– The same materials can be reused.
Examples of Cycles:
•
•
•
•
Carbon
Nitrogen
Phosphorus
Water
WHY IS NITROGEN IMPORTANT?
• Nitrogen bases make DNA and RNA
• Adenine is used in ATP
• Nitrogen makes the “amino” part of Amino
Acids (monomer of proteins).
79% of the atmosphere is made up of
NITROGEN gas (N2)
BUT we CAN’T use the nitrogen gas we
breathe!
The bond in N2 gas is so strong it can only
be broken by:
 Lightening
 Specialized bacteria
 Volcanic Activity
Bacteria that live in the soil and in symbiotic
relationships with plants, called legumes, take nitrogen
from the atmosphere and turn it into ammonia (NH3), a
form that is usable by plants.
This process is called:
Nitrogen Fixation
Other bacteria in the soil convert ammonia into nitrates
(NO3- ) & nitrites (NO2-) which plants can use, take up
through their roots.
The nitrogen animals need for proteins, ATP, and nucleic
acids comes from the food we eat, not the air we breathe!
Bacteria that live in the soil
also carry out the reverse process
Nitrates & nitrites → nitrogen gas
This is called
Denitrification
Nitrogen Cycle
• Nitrogen Cycle:
– Organisms must have nitrogen to produce amino
acids / proteins (CHON) and DNA (CHONP)
– Living things cannot use nitrogen gas in the air
– Life is possible due to nitrogen-fixation
• Nitrogen Fixation: Nitrogen gas is converted to
ammonia or other usable nitrogen source.
• Done by bacteria or lightening, and sometimes
volcanic activity
Nitrogen Cycle
WHY IS PHOSPHORUS
IMPORTANT?
Makes DNA and RNA
Transfers energy as ATP
Makes phospholipids for cell membranes
Phosphorous Cycle
The only biogeochemical cycle that DOES NOT involve the
atmosphere.
Biotic
• Plants – pulled up
through roots
• Animals – from
eating other living
things
Abiotic
• Most Phosphorous
is found in rocks and
sediment
• Dissolved in
freshwater
• Ocean sediments
Released by:
• Death and decay
Released by:
• Weathering/erosion
Water Cycle
• Cycle of processes by which water circulates
between the oceans, atmosphere, and land
• Involves precipitation as rain and snow
• Drainage into streams and rivers
• Return to the atmosphere by evaporation and
transpiration (loss of water from plant leaves).
Water Cycle