Chapter 3
3.1 – What is Ecology?
Interactions and Interdependence
 Ecology – the study of interactions among organisms and their environment
 Oikos (ec) – Greek word meaning house
 Ology – means study of
Levels of Organization
 The levels of organization that ecologists study include:
 Individuals
 Species – group of similar organisms that can breed and produce fertile offspring
 Populations – group of individuals of the same species that live in the same area
and interbreed
 Communities – different populations that live together in a defined area
 Ecosystem – The interaction of all the organisms and the environment in a given
area
 Biome – a group of ecosystems that have the same climate
 Biosphere – part of Earth in which life exists including land, water and
atmosphere
 It extends about 8km above the Earth’s surface to about 11km below
 If you could shrink earth to the size of an apple, the biosphere would be
thinner than the apple’s peel
Biotic and Abiotic Factors
 Biotic Factors – all the living organisms in an ecosystem
 Example: tree, bird, bacteria, fungi
 Abiotic Factors – nonliving factors in an ecosystems
 Example: temperature, precipitation, wind, soil, sunlight, humidity
 Habitat – area where an organism lives
 Includes both biotic and abiotic factors
 Niche – the role and position a species has in its environment
 No two species can share the same niche in the same habitat
3.2 – Energy Flow
 Sunlight is the main energy source for life
 Autotrophs
 Make their own energy
 Convert sun energy into chemical energy
 Also called a producer
 Plants are the main autotrophs on land
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 Algae are the main autotrophs in water
 Some autotrophs can produce food in the absence of light
 Chemoautotrophs – organisms use chemical energy to produce carbohydrates
 Performed by several types of bacteria
 Live in…
 Volcanic vents
 Deep ocean
 Hot springs
 Marshes
 Heterotrophs
 Get energy from other organisms
 Unable to make its own energy
 Also called consumers
 Types of Heterotrophs
 Herbivores
 Eats only plants
 Example: cows, deer, rabbits, bees, elephants, squirrels
 Carnivores
 Eats only animals
 Example: snakes, dogs, lions, crocodiles
 Omnivores
 Eats plants and animals
 Example: humans, bears, crows
 Detrivores
 Eat decomposing bits of organic matter
 Example: mites, earthworms, snails, crabs
 Decomposers
 Break down organic matter
 Example: bacteria and fungi
 Scavenger
 Ingest nonliving plants and animals
 Example: vulture, termite, beetle
Feeding Relationships
 Food Chain – a straight line series of steps by which energy is stored and passed on
to higher trophic levels
 Food Web – a network of crossing interlinked food chains that shows all the possible
feeding relationships at each trophic level
 Energy is passed through no more than four or five trophic levels
 Trophic Levels – step in a food chain or food wed
 Plants and other producers are 1st trophic level
 Consumers make up the 2nd, 3rd, or higher trophic levels
 Each consumer depends on the trophic level below it for energy
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 Energy is transferred from one trophic level to another and is never 100%
 At each trophic level only 10% of the energy taken in by the organism is stored.
The rest is used up during metabolism to process the energy
Community Interactions
 Competition – occurs when organisms of the same or different species attempt to
use the same resources
 Predator – eat other animals
 Prey – the animal a predator eats
 Symbiosis – relationship in which two species live closely together
 Three Types of Symbiosis
1. Mutualism
 Both species benefit from the relationship
 Example: plants and bacteria on roots
Shark and fish
2. Commensalism
 One organism benefits and the other is neither helped nor harmed
 Example: tree and bird nest
3. Parasitism
 One organism lives on or inside another organism and harms it
 Example: tick, ringworm
Ecological Pyramids
 Ecological Pyramid – a diagram that shows the relative amounts of energy or matter
contained within each trophic level in a food chain or food web
 Example: Ecological Pyramids
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3-3 Cycles of Matter
 Biogeochemical Cycles – process in which elements, chemical, and other forms of
matter are passed from one organism to another and from one part of the biosphere
to another
The Water Cycle
 Evaporation – process by which water changes from a liquid to a gas
 Transpiration – loss of water from plants by the process of evaporation
 Condensation – water vapor changes to a liquid
 Precipitation – water returns to the earth (rain, snow, hail)
The Carbon Cycle
 Carbon is released into the atmosphere by…
 Respiration
 Burning fossil fuels
 Volcanic activity
 Burning trees
 Carbon is taken out of the atmosphere by…
 Photosynthesis performed by plants
 Carbon is released into the ground by…
 Decomposition of plants and animals
 Carbon is taken out of the ground by…
 Mining
 Roots of plants
Nitrogen Cycle
 Gaseous nitrogen (N2)makes up 80% of the atmosphere
 Nitrogen Fixation
 Bacteria convert N2 to ammonia (NH3)
 This dissolves forming ammonium (NH4)
 Ammonification
 Bacteria degrade nitrogenous wastes and remains of organisms
 Convert NH3 to NH4+
 Nitrification
 Bacteria convert NH4 to nitrite (NO2) to nitrate (NO3)
 Denitrification
 Bacteria convert nitrate or nitrite (NO3, NO2) to N2
 N2 is released back into the atmosphere
 Humans are harming the nitrogen cycle by:
 Deforestation
 Conversion of grasslands for agriculture
 Sewage enters waterways
 Fossil fuel burning
 Vehicles having combustion engines releases NO2
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4-2 What Shapes an Ecosystem?
Ecological Succession
 Succession – changes that occurs in a community over time
 Pioneer Species – first species to populate the area
 Climax Community – a stable mature community that undergoes little or no
change in species
 Two Types of Succession
1. Primary Succession
 Succession that occurs on surfaces where no soil exists
 Example: rock surfaces formed after volcanoes erupt
2. Secondary Succession
 Succession following a disturbance that destroys a community without
destroying the soil
 Because soil already exists, secondary succession usually takes less time
than primary succession
 Example: fires, floods, farming, construction, hurricanes, tornadoes
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Gaseous Nitrogen
N2
Nitrogen Fixation
Ammonification
Denitrification
Bacteria in the soil convert
N2 → NH3 → NH4
Bacteria convert wastes and
decomposing organics to
NH3 → NH4
Bacteria convert
NO3 → N2
Autotrophs can take up
NH4 and NO3
Nitrification
Bacteria convert
NH4 → NO2 → NO3
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CO2
Organism eats plants
C6H12O6
Decomposition
Oil
Coal
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Chapter 3
3.1 – What is Ecology?
Interactions and Interdependence
 Ecology –
 Oikos (ec) – Greek word meaning ____________
 Ology – means __________ _____
Levels of Organization
 The levels of organization that ecologists study include:
 Individuals
 Species –
 Populations –
 Communities –
 Ecosystem –
 Biome –
 Biosphere –
 It extends about _____km above the Earth’s surface to about _____km below
 If you could shrink earth to the size of an apple, the biosphere would be
thinner than the apple’s peel
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Biotic and Abiotic Factors
 Biotic Factors –
 Example:
 Abiotic Factors –
 Example:
 Habitat –
 Includes both biotic and abiotic factors
 Niche –
 No two species can share the same niche in the same habitat
3.2 – Energy Flow
 _______________ is the main energy source for life
 Autotrophs

 Convert __________ energy into ____________ energy
 Also called a _______________
 ____________ are the main autotrophs on land
 ____________ are the main autotrophs in water
 Some autotrophs can produce food in the absence of light
 Chemoautotrophs –
 Performed by several types of bacteria
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 Live in…




 Heterotrophs


 Also called _______________
 Types of Heterotrophs
 Herbivores

 Example:
 Carnivores

 Example:
 Omnivores

 Example:
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 Detrivores

 Example:
 Decomposers

 Example:
 Scavenger

 Example:
Feeding Relationships
 Food Chain –
 Food Web –
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 Energy is passed through no more than ________ or ________ trophic levels
 Trophic Level –
 _______________and other producers are 1st trophic level
 _______________make up the second, third, or higher trophic levels
 Each consumer depends on the trophic level below it for energy
 Energy is transferred from one trophic level to another and is never ________
 At each trophic level only ________ of the energy taken in by the organism is
stored. The rest is used up during _______________ to process the energy.
Community Interactions
 Competition –
 Predator –
 Prey –
 Symbiosis –
 Three Types of Symbiosis
1. Mutualism

 Example:
2. Commensalism

 Example:
3. Parasitism

 Example:
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Ecological Pyramids
 Ecological Pyramid –
3-3 Cycles of Matter
 Biogeochemical Cycles –
The Water Cycle
 Evaporation –
 Transpiration –
 Condensation –
 Precipitation –
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The Carbon Cycle
 Carbon is released into the atmosphere by …




 Carbon is taken out of the atmosphere by …

 Carbon is released into the ground by …

 Carbon is taken out the ground by …


Nitrogen Cycle
 Gaseous nitrogen (N2) makes up ________% of the atmosphere
 Nitrogen Fixation

 This dissolves forming _______________ ________
 Ammonification
 ____________ degrade nitrogenous wastes and remains of organisms
 Convert _______ to _______
 Nitrification
 Bacteria convert ________ to ____________ (NO2) to ____________ (NO3)
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 Denitrification
 Bacteria convert ____________ or ____________ (NO2 and NO3) to N2
 N2 is released back into the ______________
 Humans are harming the nitrogen cycle by:





Ecological Succession
 Succession –
 Pioneer Species –
 Climax Community –
 Two Types of Succession
1. Primary Succession

 Example:
2. Secondary Succession
 Succession following a disturbance that
 Because soil already exists, secondary succession usually takes ________
time than primary succession
 Example:
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