Chapter 7 Threats to Survival Lesson 2

Science Essential Question How does a system of living and non-living things operate to meet the needs of the organisms in an ecosystem? Science Essential Question

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.

Threats to Biodiversity – Discovery Education Movie Time Threats to Biodiversity – Discovery Education