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Chapter 7
Threats to
Survival
Lesson 2
How does a system of living
and non-living things operate
to meet the needs of the
organisms in an ecosystem?
MAIN IDEA
• Different species of plants and
animals face a number of threats
to their survival.
Vocabulary For Today
Page B68
• Extinct – When the last member of a
species has died
• Migrate – To move to another region
when seasons change and food is
scarce
• Species – A group of living things
that produces living things of the
same kind
How Organisms Change Environments
Pages B68 – B69
• Every living thing causes changes to its
environment.
• These changes affect other living things.
• An environmental change caused by
humans or other organisms can have
positive and negative effects.
• Nature and humans can threaten the
survival of living things.
Natural and Human Threats
Page B70
• Humans can be one of the biggest
threats to the survival of a species.
• A species is a group of living things that
produces living things of the same kind.
• Some animals migrate, or move to
another region when seasons change
and food becomes scarce.
Can you think of an animal that migrates?
Natural and Human Barriers
• Migrating animals face natural and human
barriers.
• Natural barriers include mountain ranges.
• Some migrating birds will not cross
mountains.
• Human barriers include highways.
• Migrating caribou usually will not cross
highways.
Lesson Wrap Up
• All living things cause changes in their
environment.
• Changes in a habitat, including changes
made by humans, can have both good
and bad effects.
• There are human and natural threats to
the survival of living things.
Movie Time
Threats to Biodiversity – Discovery
Education