Transcript Unit 8: Ecology

UNIT 8: ECOLOGY
KEYSTONE REVIEW
UNIT 8: ECOLOGY
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Describe the levels of ecological organization
(from small to big)
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Organism: A form of life; an animal, plant, fungus, protist
or bacterium.
Population: A group of individuals of the same species
living in a specific geographical area and reproducing.
Community: Different populations of organisms interacting
in a shared environment.
Ecosystem: A system composed of organisms and nonliving
components of an environment.
Biome: A large area or geographical region with distinct
plant and animal groups adapted to that environment.
Biosphere: The zone of life on Earth; sum total of all
ecosystems on Earth.
UNIT 8: ECOLOGY
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Describe characteristic biotic and abiotic
components of aquatic and terrestrial
ecosystems
Abiotic: A term that describes a nonliving factor in an
ecosystem. Abiotic factors determine the plants and
vegetation.
 Biotic: A term that describes a living or once‐living
organism in an ecosystem.
 Aquatic (water ecosystem)
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Biotic: all living things
Abiotic: water, temperature, pH, water movement, salinity,
dissolved oxygen etc.
Terrestrial (land ecosystem)
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Biotic: all living things.
Abiotic: temperature, rainfall, wind, fires, elevation, land, etc.
UNIT 8: ECOLOGY
 Describe
how energy flows through an
ecosystem
Energy is not created or destroyed.
 Energy can be transferred.
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Every time energy is transferred some is lost as heat.
To trace the flow of energy start from bottom to top.
Producers are at the base.
 Primary consumers (herbivores) are next.
 Secondary consumers (carnivores) are next.
 Tertiary consumers (top level).
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UNIT 8: ECOLOGY
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Describe how energy flows through an
ecosystem
Food chains: A simplified path illustrating the
passing of potential chemical energy (food) from one
organism to another organism.
 Food webs: A complex arrangement of interrelated
food chains illustrating the flow of energy between
interdependent organisms.
 Energy pyramids: A model that illustrates the
biomass productivity at multiple trophic levels in a
given ecosystem.
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UNIT 8: ECOLOGY
 Describe
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biotic interactions in an ecosystem
Symbiosis: a relationship between two organisms.
Mutualism: both organisms benefit. (ex. Flowers and
insects)
 Parasitism: one organism benefits and the other is harmed.
(Ex. Humans and a tapeworm).
 Commensalism: one organism benefits and the other does
not benefit or is not harmed. (ex. Shark and remora)
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UNIT 8: ECOLOGY
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Competition: When individuals or groups of
organisms compete for similar resources such as
territory, mates, water, and food in the same
environment. Both organisms lose out since there are
limited resources.
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Predator-prey relationship: The populations of predators
and prey follow each other in a cycle like so:
Prey
Predator
UNIT 8: ECOLOGY
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Describe how matter recycles through an
ecosystem
Water cycle: most water is in the oceans. Evaporation
moves it into the atmosphere and sometimes onto land. It
is powered by the sun.
 Carbon cycle: carbon dioxide is absorbed by plants and
forms organic molecules through photosynthesis. Cellular
respiration releases it back into the atmosphere.
 Oxygen cycle: there is a fast exchange of oxygen between
living things and the atmosphere. There is a slow exchange
between living things rocks and soil.
 Nitrogen cycle: huge amounts of nitrogen are in the
atmosphere. Most organisms can’t use atmospheric
nitrogen. Some bacteria have to “fix” the nitrogen and
make it available in the food web.
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UNIT 8: ECOLOGY
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Describe how ecosystems change in response to
natural and human disturbances
Stable ecosystems may change very slowly. Disturbances
can cause drastic changes.
 Disturbances can be natural (fire, pioneer species, disease,
natural weather anomalies, and population fluctuations).
Humans can cause many disturbances (fire, introduced
species, climate change, and pollution).
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Climate changes: humans have introduced excess greenhouse
gasses (water vapor, carbon dioxide, methane, nitrous oxide,
and ozone) into the atmosphere. It appears to be trapping more
heat in our atmosphere. It is affecting ecosystems through
climate fluctuations and ocean levels.
Introduction of nonnative species: A species normally living
outside a distribution range that has been introduced through
either deliberate or accidental human activity; also can be
known as introduced, invasive, alien, nonindigenous, or exotic.
 Sometimes organisms that are brought into a new ecosystem
are too successful and displace native organisms. This can
lead to the native species dying out.
UNIT 8: ECOLOGY
 Describe
how ecosystems change in
response to natural and human
disturbances
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Pollution: air, water, light, thermal, noise
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SOME CHEMICALS MAY ACT AS POLLUTANTS
IF THEY:
-trap heat in the atmosphere causing the
greenhouse effect.
-fertilizer in water, causing an increase in algae and
a decrease in O2. (Nutrient/nitrogen pollution)
-mess up the hormones of organisms. (Endocrine
disrupters)
-lower the pH of rain. (Acid rain)
UNIT 8: ECOLOGY
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Describe the effects of limiting factors on
population dynamics and potential species
extinction
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Limiting factors: Chemical or physical factor that limits the
existence, growth, abundance, or distribution of an individual
organism or a population. Limiting factors determine the
carrying capacity.
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Examples:
 Predators: little or no predators will cause an increase; too many
predators will cause a decrease.
 Nitrogen: plants and animals cannot use nitrogen in gas form; it has
to go through nitrogen fixation by bacteria first. Without enough
useable nitrogen plants cannot grow well which would limit the food
available to animals. So too little nitrogen would lower the capacity,
excess nitrogen would raise the capacity.
 Food availability: too little food causes a decrease; excessive food will
cause an increase.
 Weather: storms, droughts, frosts, etc. can all decrease the carrying
capacity by decreasing things like food. Good weather can increase
the amount of food available which would increase the capacity.
 Disease: generally diseases lower the carrying capacity.
VIDEO REVIEW
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Levels of Organization
VIDEO REVIEW
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Biotic and abiotic
VIDEO REVIEW
Energy Flow
 Trophic levels
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VIDEO REVIEW
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Symbiosis
VIDEO REVIEW
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Matter Cycles
VIDEO REVIEW
Human Impact
 Threats to Biodiversity
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VIDEO REVIEW
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Limiting Factors