Chapter 2
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Ecology
Biosphere
Biotic Factor
Abiotic Factor
Population
Biological Community
Ecosystem
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Biome
Habitat
Niche
Predation
Symbiosis
Mutualism
Commensalism
Parasitism
I.
Ecology
A. Each organism depends on both living and
nonliving factors in their environment for survival
B. Scientists who study ecology are called ecologists
C. Science models are a way of creating a visual
representation of a hypothesis to test in a lab
setting
The Biosphere
II.
A. Biotic Factors
1.
2.
B.
1.
2.
3.
4.
All living things in an environment
Interactions among organisms are necessary for the
health of all species in the same geographic location
Abiotic Factors
Nonliving factors in the environment
Factors may include temperature, air or water
currents, sunlight, soil type, rainfall, or available
nutrients
Organisms depend on both abiotic and biotic factors
for survival
If an organism moves to another location with
different abiotic factors, it must adapt or it dies
III.
Levels of Organization
Organism, Population, Biological Community,
Ecosystem, Biome, Biosphere
A. Organisms, populations, and biological
communities
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1.
2.
3.
4.
Lowest level is the organism
Individual organisms often compete for the same
resources; if resources are plentiful, the population
grows
Usually there are factors that prevent a population
from becoming extremely large
Organisms may or may not compete for the same
resources in a biological community
B. Ecosystems, biomes, and the biosphere
1. Ecosystem is similar to a biological community,
except that it also includes abiotic factors
2. Ecosystem can be large or small and even overlap
3. Biome is a large group of ecosystems
4. The biosphere consists of all of the biomes; the
highest level of organization on Earth
IV.
Ecosystem Interactions
A. Interactions between organisms are important to
survival in an ecosystem (ex. Tree)
B. Habitat could be one tree or a grove of trees
C. An organism’s niche is it’s role or job
V.
Community Interactions
A. Competition
1.
2.
3.
4.
Occurs when more than one organism uses a
resource at the same time
Strong directly compete with the weak
Usually the strong survive; the weak could move to
another location
If the resource is plentiful, them competition is not
very fierce
B. Predation
1. Many species get their food by eating (predator)
other species (prey)
2. Ladybug and praying mantises are insect predators,
but also called beneficial insects (used for garden
control)
C. Symbiotic Relationships
1. Mutualism: both benefit (algae and fungi form
lichens through a mutualistic behavior
2. Commensalism: one benefits and the other gets
neither hurt or helped (clownfish and sea anemones;
clownfish get protected)
3. Parasitism: one benefits at the expense of the other
(ticks or fleas)
4. In parasitism if the host dies, so can the parasite
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Autotroph
Heterotroph
Herbivore
Carnivore
Omnivore
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Detritivore
Trophic Level
Food Chain
Food Web
Biomass
Energy in an Ecosystem
I.
A. Autotrophs
1.
2.
B.
1.
2.
3.
4.
Green plants and other organisms that produce their
own food (primary producers)
Are the foundations for all ecosystems because they
make energy available for all organisms
Heterotrophs
Also called consumers
Gets energy from consuming other organisms
Decomposers break down dead organisms
Decomposers are the primary method used to make
nutrients available for producers to reuse
Models of Energy Flow
II.
A. Food Chains
1.
2.
B.
1.
2.
Arrows normally start with autotrophs and move to
heterotrophs
Remaining energy is released into environment and
not available to organisms
Food Webs
Usually more complex than a food chain
Food webs are the most common
C. Ecological Pyramids
1.
2.
3.
Shows the relative amounts of energy, biomass, or
numbers of organisms at each trophic level in an
ecosystem
Only 10% of all energy is transferred to level above
Number of organisms at each level gets less, as you
move up the energy pyramid
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Matter
Nutrient
Biogeochemical cycle
Nitrogen fixation
Denitrification
I.
Cycles in the Biosphere
A. Connection to Chemistry
1.
In most ecosystems, plants obtain nutrients, in the
form of elements and compounds, from the air, soil,
or water
B. The Water Cycle
1.
2.
3.
4.
Constant recycling
Same water today that was here when Earth began
Approximately 90% of water vapor evaporates from
oceans, lakes, and rivers, 10% from the surfaces of
plants through transpiration
All living organisms rely on fresh water
5.
6.
7.
8.
Freshwater constitutes only about 3% of all water
Water available to living organisms is about 31%
The remaining 69% of freshwater is frozen
Processes in the water cycle are evaporation,
condensation, precipitation, transpiration, and
percolation (seepage)
C. The Carbon and Oxygen Cycle
1. All living things are composed of carbon molecules
2. Carbon and oxygen make up the molecules essential
for life
3. Green plants convert carbon dioxide and water into
carbohydrates and release oxygen back into the
atmosphere (photosynthesis)
4. Carbon dioxide is recycled when autotrophs and
heterotrophs release it back into the air during
cellular respiration
5. Carbon enters a long cycle when organic matter is
buried
6. Carbon is released from fossil fuels when they are
burned
7. Carbon and oxygen can also combine with calcium to
create calcium carbonate
D. The Nitrogen Cycle
1. Largest concentration of nitrogen is found in the
atmosphere
2. Plants and animals can’t use nitrogen directly from
the atmosphere; only from the soil
3. Nitrogen can be fixed (converted) during an electrical
storm
4. Nitrogen is often a factor that limits the growth of
producers
5. Nitrogen gets returned to the soil in several ways:
animals urinate, organisms die, or denitrification
E. The Phosphorus Cycle
1. Phosphorus is essential for the growth and
development of organisms; limits the growth of
producers
2. Short term and long term cycles
3. Producers obtain it from the soil and consumers by
eating the producers
4. When organisms die or produce wastes,
decomposers return the phosphorus to the soil
where it can be used again
5. Moves from the short term to the long term through
precipitation and sedimentation to form rocks
6. In the long term cycle, erosion and weathering of
rocks that contain phosphorus, adds it back to the
soil