Biogeochemical Cycles

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Biogeochemical Cycles

• Mrs. Stewart
• Honors Biology

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CLE 3210.3.4 Describe the events which occur
during the major biogeochemical cycles.You will
know you have mastered this standard whenYou
can predict how changes in a biogeochemical cycle
can affect an ecosystem
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Objectives

• Analyze the flow of nutrients in each
  biogeochemical cycle.
• Evaluate the impact that humans have on the
  biogeochemical cycles.

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Why do we recycle?

• Think Pair - Share

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What sustains life on Earth?

• Solar energy
• The cycling of matter, energy nutrients
• Gravity

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Two Secrets of Survival Energy Flow and Matter
Recycle

• An ecosystem survives by a combination of energy
  flow and matter recycling.

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MATTER CYCLING IN ECOSYSTEMS

• Nutrient Cycles Global Recycling
• Global Cycles recycle nutrients through the
  earths air, land, water, and living organisms.
• Nutrients - the elements and compounds that
  organisms need to live, grow, and reproduce.

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Macromolecule Review

• What element does every organic organism contain?
• What are the 5 major elements that create all the
  macromolecules?

Carbon
Carbon Hydrogen Oxygen Nitrogen Phosphorous
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Think Pair Share

• What would happen to these elements if they were
  only capable of being used once?
• Think about every time an organism is created
  and/or destroyed

They would begin disappearing (dwindling in
supply) like fossil fuels
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Biogeochemical Cycles

• These are just illustrations or representations
  to show how substances move through air, water,
  soil, rock and living organisms.

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Decomposition

• Decomposers
• ultimately responsible for recycling of chemical
  nutrients
• releasing the nutrients in detritus
• This makes nutrients available again to the
  autotrophs in the ecosystem

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Recycling

• What nutrients get recycled?
• Carbon Dioxide
• Oxygen
• Water
• Carbon
• Nitrogen
• Phosphorous

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Water Cycle
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Movement of Water

• Three important processes
• Evaporation adds water as vapor to atmosphere
  (heat)
• Bodies of water, soil, animal bodies, etc.
• Transpiration water evaporates from the leaves
  of plants
• Precipitation water released from the
  atmosphere (temperature, air pressure)
• Rain, snow, sleet, hail or fog

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Water Cycle
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Think-pair-share

• What human activities effect the water cycle?
• What do we do as humans that could have positive
  or negative effects on this cycle
• 2 minutes

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Effects of Human Activities on Water Cycle

• We alter the water cycle by
• Withdrawing large amounts of freshwater.
• Clearing vegetation and eroding soils.
• Polluting surface and underground water.
• Contributing to climate change.
• How do these changes affect the surrounding
  ecosystems?

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Objectives

• Analyze the flow of nutrients in each
  biogeochemical cycle.
• Evaluate the impact that humans have on the
  biogeochemical cycles.

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Carbon Cycle
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Photosynthesis vs Cellular Respiration

• Photosynthesis absorbs CO2 from the
  atmosphere/biosphere and releases O2
• Cellular respiration absorbs O2 from the
  atmosphere/biosphere and releases CO2

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Carbon is found in 5 major places

1. Living and dead organisms
2. Carbon Dioxide (CO2) in atmosphere
3. Organic matter in the soil
4. Fossil fuels and rock deposits
5. Oceans dissolved CO2 and shells

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Do these plants contain Carbon?

• What happens to the carbon now?

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Where is the carbon?
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Think-pair-share

• What human activities effect the Carbon-Oxygen
  cycle?
• What do we do as humans that could have positive
  or negative effects on this cycle
• 2 minutes

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Effects of Human Activities on Carbon Cycle

• We alter the carbon cycle by adding excess CO2 to
  the atmosphere through
• Burning fossil fuels.
• Clearing vegetation faster than it is replaced.

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• How do those changes affect the surrounding
  ecosystems?

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Objectives

• Analyze the flow of nutrients in each
  biogeochemical cycle.
• Evaluate the impact that humans have on the
  biogeochemical cycles.

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Nitrogen Cycle
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Nitrogen Uses

• Proteins
• Enzymes, skin, muscles, etc.
• Nucleic Acids
• DNA
• RNA

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Forms of Nitrogen

• Nitrogen is found in many forms in the atmosphere
  / ecosystem
• N2 nitrogen gas (79 of atmosphere)
• N2O nitrous oxide
• NH3 ammonia
• NH4 ammonium
• NO3 nitrate
• NO2 nitrite

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Nitrogen Fixation

• Converting N2 gas to nitrate (only usable form of
  nitrogen for most plants)
• 2 types
• Natural lightning, fires and bacteria
• Human fossil fuel combustion, fertilizer
  manufacturing

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Nitrogen-fixing bacteria

• bacteria that transform Nitrogen gas into a
  usable form (Nitrate)
• Live in the soil
• May live in the swellings on the roots of some
  plants (ex. Beans, peas, clover)
• These plants provide sugars for the bacteria, and
  the bacteria provide usable nitrogen.

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Recycling Nitrogen

• Where is Nitrogen found?
• Dead organisms (as proteins nucleic acids)
• Urine dung
• Decomposers break down and release Nitrogen as
  NH3 (ammonia)

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Nitrogen Processes

• Ammonification converting NH3 (ammonia) to NH4
  (ammonium)
• Nitrification converting NH4 (ammonium) into
  NO2 (nitrite) or NO3 (nitrates)
• Denitrification anaerobic bacteria break down
  NO3 (nitrates) and release N2 (nitrogen gas) into
  the atmosphere

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Nitrogen Sources

• Plants Nitrates from the soil
• Use to form proteins
• Animals eating plants/organisms and digesting
  the proteins and nucleic acids
• Humans have doubled the amount of fixed N2 in
  the atmosphere in the last 100 years.
• HOW?

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Too much of a good thing?

• Too much nitrogen in aquatic ecosystems results
  in
• Eutrophication excess nutrients stimulate plant
  growth (algal blooms) when these plants die,
  decomposers use up the available oxygen during
  decomposition.

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Eutrophication
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Nitrogen Cycle
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Think-pair-share

• What human activities effect the Nitrogen cycle?
• What do we do as humans that could have positive
  or negative effects on this cycle
• 2 minutes

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Effects of Human Activities on the Nitrogen Cycle

• We alter the nitrogen cycle by
• Adding gases that contribute to acid rain.
• Adding nitrous oxide to the atmosphere through
  farming practices which can warm the atmosphere
  and deplete ozone.
• Contaminating ground water from nitrate ions in
  inorganic fertilizers.
• Releasing nitrogen into the troposphere through
  deforestation.

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Effects of Human Activities on the Nitrogen Cycle

• Human activities such as production of
  fertilizers now fix more nitrogen than all
  natural sources combined.

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How does this affect the surrounding ecosystems?

• Acid rain
• creation of ground level ozone
• groundwater contamination
• eutrophication.

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• Exploring the Nitrogen Cycle Activity

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Objectives

• Analyze the flow of nutrients in each
  biogeochemical cycle.
• Evaluate the impact that humans have on the
  biogeochemical cycles.

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Phosphorus Cycle
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Overview

• Movement of phosphorus from the environment, to
  organisms, and back to the environment
• Slow process
• Normally does not occur in atmosphere because
  phosphorus rarely occurs as a gas

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Phosphorus Uses

• Essential material for animals
• Form bones, teeth, molecules (DNA/RNA)

Where do organisms get phosphorus?

• Plants absorb from soil and water
• Animals eating plants other organisms

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Cycle

• Rocks erode, and small amounts of phosphorus
  dissolve as phosphate PO4 3-, in soil and water
• Excreted in wastes from organisms
• Released by decomposers from dead organisms
• Plants absorb from soil and water, through roots
• Animals eat plants/other organisms
• Some in fertilizers and applied to fields/crops
• Washes off into streams, groundwater and soil

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Phosphorus Cycle
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Think-pair-share

• What human activities effect the Phosphorus
  cycle?
• What do we do as humans that could have positive
  or negative effects on this cycle
• 3 minutes

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Effects of Human Activities on the Phosphorous
Cycle

• We remove large amounts of phosphate from the
  earth to make fertilizer.
• We reduce phosphorous in tropical soils by
  clearing forests.
• We add excess phosphates to aquatic systems from
  runoff of animal wastes and fertilizers.

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What determines population size?
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Environment vs Habitat

• Many species can survive in more than one
  environment.
• But each species has its home or habitat.
• Fish may be able to live in fish tanks, but would
  rather live in the wild

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What do organisms need to survive?

• Basic requirements for survival include
• Food
• Water
• Shelter

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Competition

• An important aspect of the struggle for survival
  involves competition for limited resources
• Food
• Water
• Shelter
• Sunlight

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Limiting Factors

• Limiting factors are factors that affect the
  population size of a species in a specific
  environment.
• They can be abiotic or biotic.

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Predator Prey relationship

• Predators are a biotic limiting factor.
• They control population size by feeding on prey.
• There is a delicate balance that needs to be
  maintained.

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Carrying Capacity

• When all the limiting factors are considered
  together we can determine the maximum number of
  organisms that can survive in an area.

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How do we determine the Carrying Capacity of a
Species?

• All limiting factors must be taken into
  consideration.
• It is very difficult to determine the actual
  carrying capacity.

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The Lesson of the Kaibab Deer

• Purpose
• to graph data on the Kaibab deer population of
  Arizona from 19051939
• to analyze the methods responsible for the
  changes in the deer population
• to propose a management plan for the Kaibab deer
  population

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How Many Bears??
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Kaibab Forest North Rim of the Grand Canyon
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Key Idea

• All organisms have the ability to produce
  populations of unlimited size
• But their environment keeps their numbers in
  check.

• THINK-PAIR-SHARE
• How?
• List examples of limiting factors.
• 3 minutes