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7th Grade Outline 17.1
Vocabulary
Biosphere:
part of Earth that
supports organisms, is the highest level of biological organization, and is
made up of all Earth’s ecosystems.
Ecology:
the study of the
interactions that take place among organisms and the physical features of the
environment.
Abiotic factor:
all the nonliving,
physical features of the environment, including light, soil, water, and
temperature that help determine which species can survive in an area.
Biotic factor:
living or once living
organisms in the environment.
Population:
all the individuals
of one species that live in the same area at the same time and compete with
each other for food, water, mates and space.Community:
consists of groups of
populations that interact with each other in a given area and depend on each
other for food, shelter, and for other needs.
Ecosystem:
consists of a biotic
community and the abiotic factors that affect it.
Outline: The Living and Nonliving Environment 17.1
The Biosphere
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The biosphere includes the
topmost portion of Earth’s crust; all the water’s that cover the surface and
the surrounding atmosphere.
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All organisms interact with the
environment.
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Ecologists are scientists who
study interactions between organisms and their environment
Abiotic Factors
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Abiotic have effects on living
things and often determine the organisms that are able to live in certain
environments.
Water
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bodies of most organisms are 50
to 90 percent water
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Respiration, photosynthesis,
digestion and other life processes only take place in the presence of water.
Soil
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Type of soil helps in a
particular location helps determine which plants and animals live there.
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Soil type is determined by the
relative amount of sand, clay and humus in the soil.
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Humus is the decayed remains of
dead organisms, the more hums in the soil the more fertile it is.
Light and Temperature
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The availability of sunlight is
a major factor in determining where green plants and other organisms live.
Biotic Factors
Levels of Biological
Organization
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biotic and abiotic factors
studied by ecologists can be arranges into layers of organization
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Organisms, population,
community, ecosystem and biosphere
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The resources of the environment
and how the organisms use these resources determine how large a population can
be.
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Most populations of organisms do
not live alone; they interact with populations of organisms forming a
community.
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An ecosystem looks at the biotic
community and the abiotic factors that affect it.
17.2 Interactions among Living Organisms
Vocabulary
Population Density:
The size of a population
that occupies an area of limited size.
Limiting Factor:
Any biotic or abiotic
factor that restricts the number of individuals in a population
Carrying Capacity:
Largest number of
individuals an environment can support and maintain for a long period of time.
Symbiosis:
Any close
relationship between two or more species
Habitat:
Physical location
where an organism lives
Niche:
The role of an
organism in an ecosystem
Outline
Interactions Among Living
Things
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The size of a population is
always changing, some more rapidly than others
Population density
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The more individuals there are
in a given amount of space, the more dense it is
Limiting Factors
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Populations cannot grow
unlimitedly
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There are limits to: food,
water, living space, mates, nesting sites and other resources.
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As population increases, so does
competition among individuals
Carrying Capacity
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Once a population exceeds its
carrying capacity, individuals are forced to move or they die.
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At some point through population
growth resources get scarce
Biotic Potential
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The maximum rate at which a
population increases when there is a plenty of food, water, ideal weather, no
disease is it’s biotic potential
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Most populations never reach
their biotic potential
Interactions in Communities
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Populations are regulated by
actions of other populations
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Predators are biotic factors
that limit the size of populations.
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Predators also help maintain the
health of a prey population
Symbiosis
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Many species have a close,
complex relationship
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If the relationship benefits
both it is called mutualism
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If the relationship benefits one
but not the other it is called commensalism
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If the relationship benefits one
organism, but harms another it is called parasitism
Habitats and Niches
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What species eats, how it gets
its food and interactions with other organisms is part of its niche.
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Every species plays a particular
role in its ecosystem.
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Outline 17.3 Energy
flowing through Ecosystems
Vocabulary
Food Chain:
How energy in the form of
food passes from one organism to the next.
Food Web:
Series of overlapping
food chains.
Ecological Pyramid:
A model of the transfer
of energy through the food chain
Producer:
An organism that can
make its own food and release energy through chemical processes
Consumer: An
organism that eats other organisms to gain energy for itself.
Outline:
Energy Flows through
Ecosystems
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Organisms interact with other
members of that species.
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Most interactions with other
species are feeding relationships.
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Interactions involve the
transfer of energy from one organism to another.
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Energy moves through an
ecosystem in the form of food.
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Producers capture energy from
the sun and produce carbohydrates.
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Consumers feed on producers and
other consumers.
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Decomposers obtain energy when
they break down the bodies of dead organisms.
Food Chains and Food Webs
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Food chain is a simple way of
showing how energy in food passes from one organism to another.
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Food chains usually only have 3
to 4 links, due to the decrease in energy at every link.
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At each transfer of energy a
portion is lost due to activities of the organism and heat.
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A food web is a series of
overlapping food chains.
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Food web shows a more accurate
representation of the way energy moves through a community within an ecosystem.
Ecological Pyramid
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The bottom of the pyramid
represents producers.
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The rest of the levels represent
successive organisms in the food chain.
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Most energy transfer is given
off to the atmosphere as heat.
Energy Pyramid
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Energy pyramid compares the
energy available at each level in a food chain and food web
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Pyramid usually only has 3 or 4
levels
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Only 10% of the energy from that
level is available for the next level.
The Cycle of Mater
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Matter on earth is never lost or
created, it is just recycled.
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