Module 15: Ecological Principles

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Unit 6 Ecosystems

• Module 15 Ecological Principles

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I. What is the biosphere and how is it
organized? A. Biosphere Area of the earth
where life exists extends from oceans depths to
a few kilometers above land. B. Biomes An
extensive areas of similar climate and
vegetation there are six terrestrial biomes and
three aquatic biomes.
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C. Ecosystem 1. A physically distinct, self
supporting unit of interacting
organisms and their environment. Ex. Forest
or pond 2. Four important processes a.
Production of energy (usually from
sunlight) b. Energy transfer c.
Decomposition d. Reuse of nutrients 3.
Includes biotic and abiotic factors. a.
Biotic living things b. Abiotic
nonliving things Ex. Temperature, light,
nutrients
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D. Communities and Populations 1. Communities
all the ecosystems interacting biotic factors.
2. Communities may be broken down into smaller
units called populations. a. Populations A
group of individuals that belong to the same
species and occupy the same area and share
common resources. i. Each population
has a specific niche, which means total way
of life. ii. The niche includes habitat,
place in food web, competition,
interrelationships, and resource
needs (temperature, water) b. A community
may have 1000s of populations (tropical
rainforest) or relatively few (tundra)
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II. How is energy transferred in an ecosystem? A.
Trophic Levels 1. Organisms in a community
survive by either producing or consuming
food. 2. Trophic levels levels of feeding in a
community a. Producers produce food for
themselves (ex. plants). Other organisms may eat
producers. b. Consumers must take in food
(ex. fungi) i. Primary Consumers also called
herbivores (ex. cow) ii. Secondary and
Tertiary Consumers may be carnivores
(ex. lion) or omnivores (ex. bear)
iii. Decomposers as they consume, they
break down wastes and dead organisms and
return nutrients to the soil.
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B. Food Webs 1. Made up of overlapping food
chains. 2. Shows feeding connections arrows
illustrate energy transfer 3. Ex.
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C. Ecological Efficiency 1. Producers have
most available energy (sun). 2. Energy is lost
as it moves up through the food web 10
rule only 10 of the available energy is
passed to the next trophic level 3. The lost
energy is used to catch, eat, and digest
food.
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III. How is matter reused in an ecosystem? A.
Role of Decomposers 1. Decomposers break down
wastes and dead organisms 2.
Decomposition allows nutrients to be returned to
the soil and atmosphere this allows
nutrients to be reused. 3. Decomposers
include fungi, bacteria, and
invertebrates.
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B. Biogeochemical Cycles the pathway through
which a substance is recycled. 1. Water
Cycle a. Enters ecosystem by
precipitation may Infiltrate the soil (be
absorbed) or run-off into surface
water. b. Returned to atmosphere by
evaporation or transpiration (the loss of
water by plants)
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The Carbon Cycle 2. Carbon Cycle a. Powered by
two main processes i. Photosynthesis
plants and algae capture CO2 from the air
and change it into sugar (which have
carbon) ii. Respiration all living things
break down sugars for energy, which returns
CO2 to the atmosphere b. Other factors in
the carbon cycle i. Decomposition returns
carbon to the soil and atmosphere. ii.
Humans burn fossil fuels which adds CO2 to
the atmosphere.
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• Using the Carbon Cycle diagram
• What are the 4 sources /processes that ADD carbon
  to the atmosphere?
• What are the 2 sources / processes that REMOVE
  carbon from the atmosphere?
• What process do animals carry out that adds CO2
  to the atmosphere?
• What process do plants carry out that removes CO2
  from the atmosphere?
• The combustion of ___________________ by humans
  can add CO2 to the atmosphere.
• ____________________ of dead organisms may return
  carbon to the soil.
• How is carbon stored in plants transferred to
  animals?

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3. Nitrogen Cycle a. Nitrogen is essential for
living organisms so that they can build
proteins nitrogen is plentiful in the
atmosphere, but is not usable in this form. b.
Nitrogen fixation bacteria living in the root
nodules of bean plants (legumes) convert
nitrogen from the air into a more usable
form. c. Nitrogen fixation is the first of many
steps that involves bacteria and changing the
form of nitrogen.
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IV. How do living things interact in a
community? A. Competition a struggle for
resources among organisms. Ex. nesting space
for birds B. Predation 1. Predators are
organisms that consume other organisms.
Ex. Zebra eating grass 2. Prey are
the organisms that are consumed. Ex.
Earthworm being eaten by bird
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Symbiosis song! C. Symbiosis two organisms of
different species living together in a close,
permanent relationship 3 types 1. Mutualism
the two organisms benefit each other Ex.
Termite and protozoan Ex. Lichen an alga and
a fungus
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• 2. Parasitism one organism benefits and the
  other is harmed
• Ex. Tapeworm and human
• Ex. Mistletoe and tree
• Commensalism one organism benefits and the
  other is unaffected.
• Ex. Epiphytic plants on trees
• Ex. Shark and remora

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V. How do communities change over time? A.
Population growth 1. Populations will grown
until they reach their biotic potential, unless
they are limited by factors in the environment
this type of growth is known as a J-curve.
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• Limiting factors, such as availability of food,
  water, and
• space establish a carrying capacity for
  populations this type of growth is known as an
  S-curve

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3. Carrying capacity is defined as the number of
individuals an environment can support. Limiting
factors in the environment help to maintain
ecosystem stability by allowing populations to
fluctuate around the carrying capacity. This is
called dynamic equilibrium.

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a. Density dependent factors have a greater
effect on a population when there is a higher
population density (the number of individuals in
a given space). For example, competition,
predation, and the spread of infectious disease
are density-dependent factors. b. Density
independent factors influence the size of a
population regardless of its density. For
example, natural disasters such as forest fires
are density independent factors.

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• Succession is the idea that communities will
  replace other communities in a predictable,
  orderly way this happens because every community
  alters the physical factors of the environment.
• Ex. As trees grow, they produce shade.