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Chapter 3
The Biosphere
3.1 Vocabulary
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Biosphere
Species
Population
Community
Ecology
Ecosystem
Biome
Biotic Factor
Abiotic Factor
Section 1
What is Ecology?
Standards: 6A.1
Objectives:
• Explain the difference between abiotic factors
and biotic factors.
• Describe the levels of biological organization.
Biosphere
• Biosphere – consists of all life on Earth
– Earth  “Ball of Life”
– Includes land, water, and atmosphere
Ecology
• Ecology – study of the relationships among
living organisms and the interaction the
organisms have with their environment.
– Studying organisms in the field can be difficult 
too many variables to study.
Living & Nonliving Factors
• Environmental conditions include biotic and
abiotic factors:
– Biotic Factors – living organisms  (dead or alive)
– Abiotic Factors – nonliving parts  (physical
components such as temperature, air, water, wind,
humidity, sun, soil, rain, nutrients)
• Organisms depend on biotic & abiotic factors
for survival.
• Organisms are well adapted to the biotic &
abiotic factors in their environment ONLY.
Biotic and Abiotic Factors
Biotic
Environment
Abiotic
Review: Biotic or Abiotic Factors?
Levels of Organization
• Biosphere is too large and complex to study
relationships  ecologists study smaller
levels.
• Organism  lowest level
Least Complex
• Population
• Community
• Ecosystem
• Biome
Most Complex
• Biosphere  highest level
Organism
• An individual living thing.
Population
• Population – group of the same species that
share the same geographic location at the
same time.
– Same species compete for same resources
Community
• Community – groups of interacting
populations that occupy the same area at the
same time.
Ecosystem
• Ecosystem – community of interacting organisms
and the abiotic factors that affect them.
– No clear boundaries  overlap
– Changes in climate, migration, human activity 
impact stability of ecosystem
– Stable Ecosystem = Healthy  Homeostasis:
• Population of each organism & supply of resources
fluctuates at a predictable rate
• Constant flow of energy
Biome
• Biome – group of ecosystems that share the
same climate and have similar types of
communities.
– Examples: rainforest, desert, tundra, freshwater,
marine
Review: Level of Organization
A
B
D
E
Biome
Biosphere
C
F
Community
Ecosystem
Organism
Population
Ecological Methods
• Ecologists use 3 methods in their work:
1. Observation
2. Experimentation
3. Modeling
3.2 Vocabulary
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Autotroph
Primary Producer
Photosynthesis
Chemosynthesis
Heterotroph
Consumer
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Carnivore
Herbivore
Scavenger
Omnivore
Decomposer
Detritivore
Section 2
Energy, Producers, and Consumers
Standards: 3A.2, 6B.1
Objectives:
• Identify the ultimate energy source for
photosynthetic producers.
• Classify organisms as producers, consumers,
herbivores, scavengers, omnivores,
decomposers, or detritivores.
Review
• All organisms need ENERGY.
• Energy is the ability to do work.
• Energy is needed for growth, reproduction,
and other metabolic processes.
• Organisms do NOT create energy  organisms
use energy from other sources.
• Ultimate source of energy  SUN
Energy from the Sun
• Autotrophs – organisms that collect energy from
sunlight (or inorganic substances) to produce food.
– Also called PRIMARY PRODUCERS (first producers)
– Photosynthesis – captures light energy and uses it to
power chemical reactions that convert carbon dioxide and
water into oxygen and energy-rich carbohydrates (sugars
and starches)
• Used by plants, algae, phytoplankton, some bacteria
• Adds oxygen to atmosphere and removes carbon dioxide
Energy Without the Sun
• Chemosynthesis – chemical energy is used by
to produce carbohydrates
– Used by bacteria in deep-sea volcanic vents or hot
springs
Energy from Consuming
• Heterotrophs – organisms that get energy by
consuming other organisms.
– Also called CONSUMERS.
– Predator-Prey Relationship
– Examples: animals, fungus, bacteria
– Different types based on what they eat.
– Use sun indirectly
Types of Consumers
• Herbivores – eat only plants
– Examples: cow, rabbit, grasshopper
• Carnivores – eat only meat (or animals)
– Examples: lion, wolf, cat
• Omnivores – eat both plants and animals
– Examples: bears, humans
• Detritivores – eat dead plants & animals;
recycles nutrients; decomposers
– Examples: worms, fungus
Types of Heterotrophs
Herbivores
Omnivores
Carnivores
Insectivores
3.3 Vocabulary
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Food Chain
Phytoplankton
Food Web
Zooplankton
Trophic Level
Ecological Pyramid
Biomass
Section 3
Energy Flow in Ecosystems
Standards: 6B.1
Objectives:
• Describe the flow of energy through an
ecosystem.
• Model the flow of energy through an ecosystem
by creating a food chain or food web.
Energy Flow
• The sun’s energy enters Earth’s ecosystems through
photosynthetic organisms  plants & algae.
Tertiary
Consumer
3rd Trophic Level
Carnivores & Omnivores/
Heterotrophs/Secondary Consumers
2nd Trophic Level
Heterotrophs/Primary Consumers/Herbivores
1st Trophic Level
Autotrophs/Primary Producers
Models of Energy Flow
• Diagrams show the direction energy goes
between organisms.
• Trophic Level – each step in a food chain or
food web.
• Types of Models:
– Food Chain
– Food Web
– Energy Pyramid
Food Chain
• Food Chain – series of simple steps in which
organisms transfer energy by eating & being eaten.
– Aquatic Ecosystems:
• Phytoplankton – photosynthetic algae  ocean surface
• Zooplankton – small free-floating animals
Food Web
• Most organisms feed on
more than one species.
• Food Web – network of
complex interactions
formed by the feeding
relationships among the
various organisms in an
ecosystem
– More accurate
Food Web
Food Web
Food Web
Food Web Disturbances
• If krill population drops, HOW would that
affect the sizes of other populations?
Decomposers & Primary Producers
Decomposers
Primary
Producers
Ecological Pyramids
• Ecological Pyramids - shows the relative amount
of energy, biomass, or numbers of organisms at
each trophic level in an ecosystem.
– 90% of energy is utilized by organisms for cellular
processes (respiration, movement, growth, etc.)
and/or released back into the environment as heat.
– 10% of energy is available for the next trophic level.
Ecological Pyramids
• 3 Types: Energy, Population Size, & Biomass
(total mass of living organisms in a trophic level)
• Base represents producers and size decreases in
higher trophic levels.
3.4 Vocabulary
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Biogeochemical Cycle
Nutrient
Nitrogen Fixation
Denitrification
Section 4
Cycles of Matter
Standards: 3A.2, 6B.1
Objectives:
• Describe how nutrients move through the biotic
and abiotic parts of an ecosystem.
• Explain the importance of nutrients to living
organisms.
• Compare the biogeochemical cycles of nutrients.
Cycling of Matter
• Nutrients – chemical substances needed to live.
– Living organisms need specific nutrients to survive.
– Organisms composed mostly of 4 elements: carbon (C),
hydrogen (H), oxygen (O), nitrogen (N).
• Earth  closed system
• Matter changes form but neither created nor
destroyed  recycled in biosphere.
• Nutrients found in food, water, rocks, soil, air.
Cycling of Matter
• Biogeochemical Cycle – exchange of matter
through the biosphere.
– Elements pass from one organism to another and
among parts of the biosphere.
– 4 Biogeochemical Cycles
1. Hydrologic Cycle (Water Cycle)
2. Carbon Cycle
3. Nitrogen Cycle
4. Phosphorus Cycle
Water Cycle
• Life needs water
• Water is found in the atmosphere, Earth’s
surface & underground, & in living organisms.
– Evaporation – sun’s energy changes liquid  gas
– Transpiration – evaporation of water from plants
– Condensation – cold temps. changes gas  liquid
– Precipitation – liquid water falls from sky
– Respiration –organisms produce water
– Elimination – organisms need water to eliminate
waste
Water Cycle
Carbon Cycle
• Life needs carbon  macromolecules (lipids,
carbohydrates, proteins, nucleic acids).
• Carbon is found in the atmosphere, minerals &
rocks, fossil fuels, soil, & aquatic sediments.
• Organisms play a major role in recycling:
– Photosynthesis – plants take in CO2  sugar
– Respiration – organisms break down sugar  CO2
– Decomposition – decomposers break down carbon
compounds when organisms die  CO2
– Digestion - Producers  Consumers  CO2
– Combustion – burning wood/fossil fuels  CO2
– Weathering – bones & shells form rocks  CO2
Carbon Cycle
Nitrogen Cycle
• Life needs nitrogen  make proteins & nucleic
acids.
• Nitrogen is found in the atmosphere (N2), living
organisms, soil, & aquatic sediments.
• Organisms play a major role in recycling:
– Nitrogen-Fixation – nitrogen-fixing bacteria found in
soil, plant roots, or aquatic ecosystems convert
nitrogen into usable forms for plants such as ammonia
or nitrates.
– Decomposition – decomposers return nitrogen into soil.
– Denitrification – soil bacteria break down nitrogen
compounds in soil & release N2 back into atmosphere.
Nitrogen Cycle
Phosphorus Cycle
• Life needs phosphorus  DNA & RNA
• P does not cycle in atmosphere. P is found in
minerals & rocks, soil, & aquatic sediments.
• Organisms play a major role in recycling:
– Weathering of rocks & sediments  releases P
– Plants take in P  absorb from soil or water
– Decomposition – decomposers break down P
compounds when organisms die
– Digestion - Producers  Consumers
– P is mined  produce fertilizer for crops
Phosphorus Cycle