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4th Grade Science - Chapter 4 Changes In Ecosystems

Book: Science By Scott Foresman Changes In Ecosystems Vocabulary And Test Review
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Side ASide B
What are 3 key things about Ecosystems?
They are healthy when their parts are in balance. All living things are interrelated - what happens to one population affects the entire community. Balanced ecosystems are constantly...
What happens when the number of organisims in a population increases?
All of the other living things population in the ecosystem will increase.
What are two things that might prevent a plant population from growing in size?
There are too many plant eating animals in the ecosystem. There hasn't been enough rain to help the grass grow. Other animals may have eaten many more of the grass eating animals.
Competition
When two or more species must use the same limited resources.
What are two behaviors that help animals avoid or reduce competition?
Living in groups Hunting in the morning or evening. Two different organisms live together to assist each other.
Parasite
The organism in a relationship that is helped by the other.
Host
The organism in a relationship that is harmed by the other.
What might happen to a parasite if its host were to die?
The parasite may die because it does not have any food from the host.
Succession
Gradual Change from one community of organisms to another.
Give an example of succession. 
Usually occurs in stages. Example: Bare land becomes grassland, grassland becomes shrubs, shrub land becomes forest land. 
Extinct
When a species dies out and is gone forever.
What are 3 reasons that an animal may become extinct?
Changes in the earth's environment: Climate changes volcanoes hurricanes meteors, habitat destruction hunting
Endangered Species
Populations of a species that have been reduced so much that they are in danger of becoming extinct.
Can endangered and threatened species sometimes lave an area to search for a more suitable environment?
YES
What are some examples where rapid change can help an ecosystem?
A forest fire - clears away dead plant matter and assists trees to creat a new forest by forcing sealed cones to release seeds. Volcanic Ash - enriches the soil. Floods - create more...
Name two processes that change an environment over a very long period of time.
Erosion Forest regrowth canyons being created lakes being created
Name two processes that change an environment rapidly.
Forest Fires Hurricanes Floods Volcanic Eruptions
What are some of the examples of ways that people disturb the balance in the ecosystem?
Cutting down trees to make houses and paper. Clearing prairies to plant crops or build roads. Polluting the air and water.
What are some examples of air pollution?
Automobile fumes Large factories that produce smoke Chemicals that farmers spray on their fields.
What are some examples of water pollution?
Chemicals that get into the rivers, lakes and oceans. Sewage Oil Spills
Hazardous Waste
Substances that are harmful to humans and other organisms.

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