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Study Guide Ecosystem Test
Ecology is the study of interactions that take place between organisms and their environment.
Abiotic factors: non-living (physical) factors in the environment (air, temperature, light,
soil, water, rocks, and nutrients)
Biotic factors: living or dead organisms in the environment
Producer or autotroph: organisms that use sunlight to produce food (mostly plants)
Consumer or heterotroph: organisms that eat (consume) other organisms for energy
Decomposers: are organisms that get their food by breaking down the remains of dead
organisms or animal waste (“nature’s recyclers”) (bacteria and fungi)
Symbiosis- a close long term relationship between two different organisms
There are 3 types of symbiosis:
1. Mutualism (+/+): type of symbiosis in which both species benefit (Ants living in
the tropical acacia trees- trees are protected when ants attack animals that
try to feed on the tree and ants receive nectar and shelter from the tree.)
2.
Commensalism (+/0): type of symbiosis in which one species benefits and the
other species is neither harmed nor benefited (Spanish moss grows on the
branches of trees. The moss gets a habitat and the tree gets nothing.)
3. Parasitism (+/-): type of symbiosis in which one species benefits and the other
species is harmed (Ticks feed on dogs.)
Competition- when two or more individuals or populations try to use the same limited resource
such as food, water, shelter, space or sunlight
There are 2 major reasons for competition:
1. carrying capacity- the largest population that an environment can support at
any given time
2. limiting factor- a factor that limits population growth such as food, water,
shelter, space or sunlight
Predation-when one organism preys on another organism
There are 2 organisms involved:
1. predator- an animal that hunts other animals
2. prey- an animal that is hunted
3. Five Levels of Environmental Organization:
Organism (Level 1) any living thing that can live on its own
Population (Level 2) A population is a group of organisms of the same species living in one area.
(ex. penguins, oak trees)
Community (Level 3) A community is made up of all of the populations of different species in an
area but not the abiotic factors of that environment.
Ecosystem (Level 4) made up of a community of organisms and its abiotic environment
Biosphere (Level 5) the part of Earth where life exists
Definitions:
habitat- the part of an ecosystem in which an animal lives
niche- the role an organism plays in an ecosystem and how an organism interacts with the biotic
and abiotic factors in its environment.
A niche can include an organism’s habitat, its role in the environment and the
abiotic factors in the organism’s environment.
omnivore- consumer that eats a variety of meat, fruit and vegetables
herbivore- consumer that eats plants (cow)
carnivore- consumer that eats only animals (wolf)
food chain- diagram that shows the flow of energy/ The original source of energy for a food
chain is the sun.
scavenger- an organism that feeds on dead animals
energy pyramid- A diagram that shows the loss of energy, which results as energy passes
through the ecosystem's food chain, from the producers to the top predators. The base
(producers) contains the most energy; the top has the fewest organisms and the least
amount of energy. When moving up the pyramid the animals get larger in size.
food web- shows all the ways energy flows to and from all organisms in an ecosystem