Name _________________________ECOLOGY
TEST STUDY GUIDE
What you should understand:
1. Energy enters an ecosystem in the form of sunlight and flows through the system to each cell and
organism.
2. Matter interacts, changes, and recycles through an ecosystem.
3. Populations of organisms survive by maintaining interdependent relationships with each other
and by using available biotic and abiotic resources from the environment.
4. Species depend upon one another and the environment for survival.
5. Energy is transferred through interdependent systems to support life.
Living Things and the Environment (Ch. 20:1)
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An organism's habitat provides food, water, shelter, and space necessary for the organism to live,
grow, and reproduce.
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An ecosystem includes Biotic and Abiotic factors.
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Abiotic factors include water, sunlight, oxygen, temperature and soil
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Biotic factors include all living things in an ecosystem.
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Given adequate biotic and abiotic resources, an ecosystem will maintain equilibrium and continue
indefinitely.
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A population consists of only one species
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Different populations living together make up a community
Ecosystem -All living and non living things interacting in an area
Habitat -The place where an organism lives and provides the things the organism needs
Biotic factor -A living part of an organism
Abiotic factor -A non- living part of an organism
Population -All the members of one species in a particular area
Community -All the different populations together in an area
Ecology -The study of how living things interact with each other and their environments
Biodiversity- The number of different species in an ecosystem. ( bio= life; diversity =different forms of)
Interactions Among Living Things (Ch. 20:3)
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Over time, species of organisms develop adaptations and behaviors that help them to succeed in their
environments.
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The three major types of interactions between organisms are competition, predation, and symbiosis
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Symbiosis is a close relationship between two species. The three types of symbiotic relationships are
mutualism, commensalism, and parasitism
Niche An organism’s particular role in an ecosystem or how it makes a living
Competition -The struggle between organisms for the limited resources in a habitat
Predation -An interaction in which one organism hunts another animal for food.
Predator -A carnivore that hunts and kills other animals for food and has adaptations that help the animal catch
the prey
Prey -An animal which a predator feeds upon
Symbiosis -A close relationship between two organisms in which al least one of the organisms benefits.
Mutualism -A type of symbiosis in which both partners benefit from living together.
Commensalism - A relationship between two species in which one species benefits and the other is neither
helped nor harmed.
Parasitism -A relationship in which one organism lives in or on a host and harms it.
Parasite -An organism that lives in or on a host, causing harm to the host.
Host -An organism that provides a source of energy or a suitable environment for another organism to live
Examples of the three types of symbiotic relationships:
1. Mutualism - There are birds that eat the fruits of plants and later deposit the seeds with a little bird
manure as fertilizer. The birds get nutrients and the plants get their seeds distributed in the environment.
2. Parasitism - A mosquito can take blood from another animal. The mosquito (parasite) may carry a
deadly virus and takes blood from the animal (host) and the animal is hurt by the relationship..
3. Commensalism - A bird builds a nest in a tree. The bird gets a nest, and the tree doesn’t mind.
Energy Flow in Ecosystems (Ch. 21:1)
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The energy role of an organism is that of a producer, a consumer, or a decomposer.
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Producers are the source of all life in an ecosystem.
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The four types of CONSUMERS are:
o herbivores- eat plants only
o carnivores- eat animals only
o omnivores- eat both plants and animals
o scavengers- eat things found already dead

DECOMPOSERS return nutrients (matter) back into the environment, where they can be used
again.
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A FOOD WEB shows the path energy and nutrients travel through an ecosystem.

At each level UP in an energy pyramid, there is less energy than the level lower. Only about 10%
of the energy is transferred up the energy pyramid. Most is transferred as heat to the abiotic parts of
the ecosystem.
Producer -An organism that can make it’s own food.
Consumer -An organism that obtains energy by feeding off another organism
Herbivore -an animal that only eats plants
Carnivore -An animal that only eats another animal
Omnivore -An organism that eats plants and other animals
Scavenger an animal that eats the remains of another animal
Decomposer -an organism that breaks down nutrients and returns them to the soil and water
food chain -A series of events in which one organism eats another
food web -The pattern of overlapping food chains in an ecosystem
energy pyramid -A diagram that shows the amount of energy that moves from one feeding level to
another in a food web
Cycles of Matter (Ch. 21:2)


Matter CYCLES through an ecosystem.
Energy does not make a complete cycle through living things in a food web. Only a small part is
passed between living organisms. Most energy is used by the organism or is transferred as heat.
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Nutrients are necessary building blocks of living things.
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The water cycle includes these three processes: evaporation , condensation ,precipitation, &
transpiration.
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Transpiration- evaporation of water through the leaves of plants
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The nitrogen cycle includes decomposers that break down wastes and put nutrients into the soil.
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The nitrogen cycle includes bacteria that live on the roots of some plants and “fix” the nitrogen into
compounds.
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When decomposers break down the matter contained in plants and animals, the molecules of matter
can be recycled through the ecosystem and used by plants to produce food or as building material for
all organisms.
oxygen cycle – the cycling of oxygen through the environment through photosynthesis and respiration.
carbon cycle – the cycling of carbon through the environment
decomposition / decay- the breakdown of living tissue, done by the FBI (fungus, bacteria, and
invertebrates)
nutrient- chemical building blocks of organisms; nutrients are recycled through cycles of matter
nitrogen fixation- the way bacteria in the soil convert nitrogen gas to a usable form for plants and animals
nitrogen cycle – the cycling of nitrogen through the environment by growth, consumption and decay.