Chapter 3: The Biosphere

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Chapter 3 The Biosphere

• The Study of Ecology

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What is Ecology?

• Ecology is the scientific study of interactions
  among organisms and between organisms and their
  environment

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Why do we study ecology?

• We live in the natural world and use its
  resources (water, space,food, etc)
• The natural world effects our lives (weather,
  fire, economy)
• To protect biodiversity

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Levels of Organization

• Ecologists recognize there is a hierarchy of
  organization in the environment biosphere, biome
  ecosystem, community, population, and organisms

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Levels of Organization
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What is a Biosphere?

• Part of Earth in which life exists including
  land, water, and air or atmosphere

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What is a Biome?
Temperate Forest
Tundra

• A group of ecosystems that have the same climate
  and similar dominant communities

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What is an Ecosystem?

• A collection of all organisms that live in a
  particular place, which includes the nonliving,
  or physical, environment

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What is a Community and a Population?

• A community is assemblage of different
  populations that live together in a defined area

• A population is a group individuals that belong
  to the same species and live in the same area

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How Do We Study Ecology?

• Observing
• Experimenting
• Modeling (Ecological phenomena that occur over
  long periods of time)

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How Do Organisms Obtain Energy in an Ecosystem?

• Sunlight is the main energy source for life on
  Earth
• Autotrophs will then use the energy from the sun
  (or chemicals) to make their own food
• Autotrophs are also known as producers
• Examples of autotrophs plants, algae,
  cyanobacteria

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How Do Organisms Obtain Energy in an Ecosystem?

• Autotrophs use photosynthesis to convert
  sunlight, carbon dioxide, and water into oxygen
  and carbohydrates

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How Do Organisms Obtain Energy in an Ecosystem?

• What if there is no light in the ecosystem?
• The autotrophs will use chemosynthesis, which is
  a process that uses chemical energy to produce
  carbohydrates (ex bacteria living in volcanic
  vents)

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How Do Organisms Obtain Energy in an Ecosystem?

• Organisms that rely on other organisms for energy
  are known as consumers or heterotrophs

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Types of Heterotrophs

• Herbivores- consume only plants
• Carnivores- consume only meat
• Omnivores- consume both plants and animals
• Detritivores- consume plant and animal remains
  (earthworms, mites, crabs)
• Decomposer breaks down organic matter to obtain
  energy (bacteria fungi)

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Feeding Relationships

• Energy in an ecosystem flows in one direction
  (from sun to the heterotrophs)
• Food chain- a series of steps in which organisms
  transfer energy by eating and being eaten

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Food Chain
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Food Web
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Transfer of Energy

• Each step in a food chain or food web is called a
  trophic level
• Autotrophs make up the first trophic level,
  consumers make up 2nd, 3rd, 4th or higher levels
• Only about 10 of energy is transferred to
  organisms at the next trophic level

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Transfer of Energy

• If 10 of solar energy is captured by plants then
  animals who eat the grass gain only 10 of that
  energy (1), animals who those animals gain 10
  from that (.1)
• 10 --gt 1 --gt .1

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What is Biomass?

• Biomass is the total amount of living tissue
  within a given trophic level
• A biomass pyramid can show you much food is
  available to each trophic level

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Recycling Matter in the Biosphere

• Elements, chemical compounds, and other forms of
  matter are passed from one organism and from one
  part of the biosphere to another in
  biogeochemical cycles

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Important Biogeochemical Cycles

• Water cycle
• Carbon Cycle
• Nitrogen Cycle
• Phosphorus Cycle

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The Water Cycle
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The Water Cycle

• Water moves between the ocean, atmosphere, and
  land
• Water evaporates from bodies of water into the
  atmosphere
• Water can also enter the atmosphere through
  transpiration (process by which water is lost
  through the leaves of plants)

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Nutrient Cycles

• A nutrient is a chemical substance that an
  organism needs to sustain life
• Important nutrient cycles
• Carbon Cycle
• Nitrogen Cycle
• Phosphorus Cycle

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The Carbon Cycle

• Carbons Roles
• Ingredient in living tissue
• Important component of animal skeletons (CaCO3)
• Important component of the atmosphere (CO2)

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The Carbon Cycle

• Carbon enters the atmosphere by
• Respiration
• Geochemical processes
• Human activities
• Carbon is taken up by
• Photosynthesis
• Burial and decomposition of dead organisms
  (formation of fossil fuels)

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The Carbon Cycle
CO2 in Atmosphere
CO2 in Ocean
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The Nitrogen Cycle

• The roles of nitrogen
• Important component of amino acids
• Major component of fertilizer (NO3-)
• Major component of atmosphere (N2)

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The Nitrogen Cycle

• Nitrogen gas (N2) cannot be used by plants so it
  must be converted into a usable form
• Soil bacteria convert nitrogen gas into ammonia
  (NH3) in the process of nitrogen fixation
• More soil bacteria convert ammonia into nitrates
  (NO3-) and nitrites (NO2-) a usable form
• Other soil bacteria then convert nitrates and
  nitrites back into nitrogen gas, which is known
  as denitrification

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The Nitrogen Cycle
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The Phosphorus Cycle

• Roles of Phosphorus
• Important component of DNA and RNA
• Does not enter atmosphere (gas)
• Steps
• Phosphorus is found in rocks and sediment which
  gets moved by water
• Plants absorb phosphorus in the form of phosphate
  from soil and water
• Heterotrophs consume plants

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What is a Limiting Nutrient?

• A nutrient that is scarce of cycles very slowly
• When an aquatic ecosystem receives a large amount
  of a limiting nutrient it immediately increases
  the amount of algae, which is known as algal bloom

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Algal Bloom

• What is the result of algal bloom?