Transcript ppt

Organisms and Their Environment
Ecology is the study of how organisms
interact with their environments.
The environment includes abiotic
(nonliving) and biotic (living) components.
We study ecology at many levels, including
the individual, population, community, and
ecosystem.
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Organisms and Their Environment
CHECK YOUR NEIGHBOR
Prairie dogs living in Nebraska represent:
A. A species
B. A population
C. A community
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Organisms and Their Environment
CHECK YOUR ANSWER
Prairie dogs living in Nebraska represent:
A. A species
B. A population
C. A community
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Species Interactions
Food chains and food webs describe which
species eat which other species. These feeding
levels—called trophic levels—include
producers and consumers.
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Species Interactions
Other types of species interactions include:
• Competition—species compete when their
niches overlap.
• Symbiosis—species may live in close
association with one another. A symbiotic
relationship may involve parasitism,
commensalism, or mutualism.
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Kinds of Ecosystems
There are terrestrial and aquatic ecosystems.
Terrestrial ecosystems are called biomes.
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Energy Flow in Ecosystems
All organisms need energy in order to grow, reproduce, and perform
the activities necessary for survival.
The amount of organic matter in an ecosystem is its biomass.
The rate at which an ecosystem’s producers build biomass is the
ecosystem’s primary productivity.
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Energy Flow in Ecosystems
On average, only about 10 percent of the energy at one
trophic level becomes available to the next level. The
other 90 percent is:
• Uneaten organisms
• Heat lost to the environment
• Feces
• Maintenance
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Integrated Science: Energy Leaks
Where Trophic Levels Meet
• Moving energy from one trophic level to another involves
a long series of chemical reactions.
• Because every chemical reaction involves some energy
loss to the environment, we see why so much energy
leaks from one trophic level to the next.
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Kinds of Ecosystems
There are eight biomes on Earth:
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Tropical forests
Temperate forests
Coniferous forests
Tundra
Savannas
Temperate grasslands
Chaparral
Deserts
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Kinds of Ecosystems
Aquatic ecosystems include freshwater and
saltwater environments as well as
estuaries where freshwater and saltwater
meet.
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Kinds of Ecosystems
All lakes and ponds can be divided into three zones:
• The littoral zone—close to the water surface and to shore, relatively
warm because of its exposure to sunlight.
• The limnetic zone—close to the water surface but far from shore,
occupied largely by plankton, organisms that float in the water rather
than swim actively.
• The profundal zone—deep water habitats in ponds and lakes. Most
organisms in the profundal zone consume organic debris that drifts
down from above.
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Kinds of Ecosystems
Species that live in the flowing waters of
rivers and streams usually have
adaptations that allow them to keep from
being washed away: hooks, suckers,
strong swimming ability.
Algae often occupy the base of the food
chain in river and stream habitats.
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Kinds of Ecosystems
Estuaries are habitats where freshwater rivers join
oceans.
Estuarine plants, such as certain seaweeds, marsh
grasses, and mangroves, have adaptations that
allow them to deal with changing salinity
conditions.
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Integrated Science: Materials
Cycling
Many substances on Earth travel through a
continuous cycle from living organisms to
the abiotic environment and back—these
are biogeochemical cycles.
Three of these cycles involve water, carbon,
and nitrogen.
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Integrated Science: Materials
Cycling
The water cycle:
• Water evaporates from the
oceans into the atmosphere.
• Water is moved around the
atmosphere by winds.
• Water precipitates as rain or
snow over ocean or land.
• Water moves into the biotic
world when it is absorbed or
swallowed by organisms. Some
of this water then passes up the
food chain. The rest is returned
to the abiotic environment in a
variety of ways, including
through animal respiration,
perspiration, excretion, and
elimination, and evaporation
from plant tissue.
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Integrated Science: Materials
Cycling
The carbon cycle:
• Most of the inorganic carbon on
earth exists as carbon dioxide and is
found either in the atmosphere or
dissolved in ocean waters.
• Plants and other producers convert
carbon dioxide to glucose during
photosynthesis.
• Carbon is returned to the
environment by living organisms as
carbon dioxide, a product of cellular
respiration.
• Because atmospheric carbon
dioxide traps heat on the planet, this
has resulted in global warming.
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Integrated Science: Materials
Cycling
The nitrogen cycle:
• Nitrogen is found primarily as
nitrogen gas, the dominant
component of the Earth’s
atmosphere.
• In order for living organisms to
make use of nitrogen, it has to
be converted into usable form.
Living organisms rely on
bacteria to accomplish this
transformation. Nitrogen is
converted to ammonium by
nitrogen-fixing bacteria in soil,
and then to nitrates by
nitrifying bacteria.
• Nitrogen returns to the abiotic
environment when it is
converted back to nitrogen gas
by denitrifying bacteria.
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