Ecology Unit Test
NTK/SG-Academic Biology
Keystone Eligible Content
B411 Describe the levels of ecological organization (ie organism, population, community, ecosystem, biome, and
biosphere).
B412 Describe the characteristic biotic and abiotic components of aquatic and terrestrial ecosystems.
B421 Describe how energy flows through an ecosystem (eg food chains, food webs, energy pyramids).
B422 Describe biotic interactions in an ecosystem (eg competition, predation, symbiosis).
B423 Describe how matter recycles through an ecosystem (ie water cycle, carbon cycle, nitrogen cycle, oxygen
cycle).
B424 Describe how ecosystems change in response to natural and human disturbances (eg climate changes,
introduction of nonnative species, pollution, fires).
B425 Describe the effects of limiting factors on population dynamics and potential species extinction.
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Ecology is the study of the interactions of organisms with one another and with their physical
environment.
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Biosphere - part of the Earth in which life exists.

Ecosystem - consists of an area’s physical features and living organisms.
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System- a set of interacting or interdependent components that form an integrated
whole
o
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Abiotic factors - physical features

Ex. elevation, humidity, rainfall

(SWATS: soil, water, air, temp, sunlight)
Biotic factors - living organisms

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Ex. snails, worms, plants, insects
Community - all the populations of organisms living in a given area.
o
Ecosystems rarely function independently of one another because they are connected by
both living and non-living features.

Ecological succession - an existing community of organisms is replaced by a different community
over time.
o
Can occur where no living community existed before (like a volcano arising from the sea).
o
Can also occur following a dramatic change (like a forest fire).
o
Succession leads to a collection of organisms called a climax community.
Biomes –see “Biomes Outlines Lab” for specifics of each Biome

Biome - an environment that has a characteristic climax community.
o Terrestrial- associated with a land environment
 Tropical
Ecology Unit Test
NTK/SG-Academic Biology
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 Tropical Rain Forest
 Grassland
 Tropical Grassland
 Temperate Grassland
 Desert
 Temperate
 Temperate Deciduous Forest
 Temperate Rain Forest
 Taiga
 Tundra
Aquatic- associated with a water environment
 Freshwater- (rivers, streams, ponds, lakes, wetlands)
 Estuaries
 Marine (intertidal zone, coastal ocean, open ocean)
Habitat- an area that provides an organisms with its basic needs for survival
Endemic species- a species found in its originating location and is generally restricted to that
geographic area
Non-native species – species introduced into an area outside of their rang by accidental or
deliberate human activity
-can also be called: introduced, invasive, alien, nonindigenous, or exotic
Energy Flow in Ecosystems

Of all the sun’s energy the reaches the Earth’s surface, only about 0.1% is used by living things.

Energy cannot be recycled or used again!

For this reason, we refer to the movement of energy through an ecosystem as a flow, not a cycle.
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Biochemical conversion- the changing of organic matter into other chemical forms such as fuels
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Bioenergetics- the study of energy flow (energy transformations) into and within a living system

The sun is the ultimate source of energy for living things.
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Producers - organisms that make their own food via photosynthesis.

Consumers - organisms that get their energy directly or indirectly from producers.
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o
Primary consumers - also called herbivores; plant eating animals.
o
Secondary consumers - animals that eat primary consumers.
Trophic level - each step in a series of organisms eating other organisms.
o
At each higher trophic level, less and less of the energy originally captured by the
producers is available.
o
Only about 10% of the energy from one trophic level can be used by the animals at the next
trophic level!

Herbivores - organisms that eat only plants.
Ecology Unit Test
NTK/SG-Academic Biology
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Carnivores - organisms that eat only animals.
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Omnivores - organisms that eat plants and animals.
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Decomposers - organisms that obtain energy from non-living organic matter
Ecosystem Relationships
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Food chain - simplest feeding relationship linking animals and plants in the biosphere.
o
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Usually contains 3-5 total organisms.
Food web - complex relationship formed by interconnecting and overlapping food chains.
o
Competition- finite amount of resources to compete over
o
Predation- one species uses another as food
o
Symbiosis-a close and usually obligatory association of two organisms of different species
that live together, often to their mutual benefit

Commensalism –one organism benefits without affecting the other

Parasitism –one organism benefits (the parasite), at the expense of the other (host)

Mutualism – each organism benefits
Nutrients are Recycle Through Ecosystems
– see “Biogeochemical Cycles
Lab” for examples of each cycle

nutrients are recycled and used again and again.

Biogeochemical cycle - nutrients use these processes to move through the biosphere.
o

Water cycle - movement of water between the atmosphere and Earth.
o
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Ex. Water, carbon, nitrogen, oxygen cycles
Consists of alternating cycles of evaporation and condensation.
Carbon Cycle- movement of Carbon through the biosphere
o
Carbon- required for all organic compounds
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Oxygen Cycle- movement of Oxygen through the biosphere
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Nitrogen cycle - movement of nitrogen through biosphere.
o
Most can’t be used directly by living organisms - it must be converted into more usable
forms.
o

Nitrogen - element required by living organisms to build proteins.
Limiting factor - the nutrient that is in short supply that limits an organism’s growth.