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STUDY GUIDE
Chapter 18 Test
18.1: Everything is Connected
Ecology: the study of the relationships of organisms with one another and with their environment.
Biotic: Living factors. Includes anything alive in the environment.
Abiotic: Nonliving factors. Abiotic factors include water, soil, light, and temperature.
Organization in the Environment
Organism: 1 single living thing.
Population: a group of individuals of the same species that live together.
Communities: all the different types of species that live and interact in an area.
Ecosystems: include the different types of organisms within the community and the abiotic environment.
Biosphere: the part of the Earth where life exists. The biosphere extends from the deepest parts of the ocean to
high up in the air.
18.2: Living Things Need Energy
Organisms can be divided into 3 groups based on how they obtain energy:
1.
2.
Producers: use sunlight directly to make food. They do this through the process of photosynthesis.
Consumers: eat other organisms to get energy.
a.
b.
c.
d.
3.
Herbivore: eat plants
Carnivore: eat animals
Omnivore: eat both plants and animals
Scavenger: eat dead animals
Decomposers: break down dead organisms. They are nature’s recyclers, fungus and bacteria.
Food Chains, Food Webs, and Energy Pyramids
Food Chain: a diagram that shows how energy in food flows from one organism to another.
Food Web: a diagram that shows the food relationships between organisms in an ecosystem.
Energy Pyramid: Triangular diagram that shows an ecosystem’s loss of energy, which results as energy passes
through the ecosystem’s food chain.
Limiting Factor: A resource that is so scarce, it limits the size of a population. For example, if there is enough water
for 5 lions, then 5 lions or less will live there. The limiting factor is water.
Carrying Capacity: the largest population that an environment can support. For example, if there is enough water
for 5 lions, then 5 lions or less will live there. The carrying capacity is 5 lions.
Competition: When 2 or more individuals or populations try to use the same resource. For example, two lions
compete for the same mate.
Predator: Animal that does the hunting. For example: Owl
Predators have adaptations which help them to catch their food.
Prey: Animal that gets eaten. For example: Mouse
Prey have adaptations which help them to escape predators.
Symbiosis: A close, long-term association between two or more species. At least one species benefits from this
relationship. There are 3 types of symbiosis.
1.
Mutualism: both species benefit
2.
Commensalism: one species benefits and the other is not affected.
3. Parasitism: one species benefits and the other is harmed.