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Transcript
Science 7 Unit A Interactions and Ecosystems 3.0 Changes can be observed and monitored in ecosystems 3.1 Investigating the Distribution of Living Things in an Environment Read pages 50 and 51 and answer the following questions: 1. It is believed that the Tyrannosaurus rex died about _______ millions years ago by a dramatic, _____________ change in its ecosystem. The “great auk” died around the year ___________, and its’ death was caused by _____________________ by the Europeans. 2. Ecosystems are always changing: some changes are natural changes, like ____________ or _______________ that can cause massive, long-term changes to ecosystems. Sometimes the changes are caused by ___________ activity, like building dams and clearing ______________. 3. Think about our schoolyard here at Delburne School. List some changes you have noticed in the years you have been here. ____________________________ ________________________ ____________________________ _________________________ Have these changes been “natural” changes, or have they been caused by human impact? ________________________________________________________ 4. To help with counting, scientists estimate the _______________ of living things in an area by a technique called _________________. This technique is used when it is too ______________ to count each living thing. Page 52 has a “mathLink” section that talks about a specific kind of sample. A staked out area that is to be studied is called a ______________, and can be square, rectangular or _______________ in shape. Studying the area inside is called _____________ _______________. Science 7 Unit A Interactions and Ecosystems 3.2 Interactions and Changes Occur in Ecosystems Read pages 55 – 60 and answer the following questions 5. Imbalances in ecosystems may create problems in that ecosystem. Sometimes, human _____________ has caused imbalance. For example, humans in the past have destroyed wetland ecosystems by draining them to be replaced by _________________ and __________________. Others were ______________ by pollution. We now recognize the importance of wetlands, and many steps have been taken to _____________ and preserve them. 6. The infoBIT on page 56 talks about the importance of dragonflies as indicators of problems in a wetland ecosystem. If dragonflies disappear from a pond, what should we be concerned about? __________________________ 7. Everything changes, including ecosystems. Some ways that changes can occur are through ___________________, _______________________, predation and weather. Bioinvasion 8. Remember, “bio” means “life”, or “living”. Think of what the word “invasion” means. Do you think you have a little understanding of what “bioinvasion” might mean? _________ Many plants and animals that we might think are common to Canada have actually come from _______________ else. ______________ settlers brought many of these with them from their home countries. Scientists call this species introduction __________________. Some of these species that were brought here were stronger than the native species (species that were here already), or they had no natural ______________. Therefore, the new species could quickly ________________. 9. European starlings are an example of bioinvasion. They were put into New York’s ______________________ and now number over 200 _____________ in North America. They cause problems in _____________ fields and are hazards at _________________. They compete with __________________, woodpeckers and __________________ for nesting sites. 10.Zebra mussels were first noticed in our Great Lakes in 1988. They probably came over on ships from ______________. House sparrows were also released in ___________________’s Central Park over 100 years ago. They complete for food and ________________ sites with many native birds. And more than ____________ of Canada’s plant species are not native. Competition 11.All living things compete with all other living things in their community for resources like ___________, water, and __________ to live. There is only so much of each resource, so all living things are always trying to get enough to meet their ___________. Now tell me, what happens if a living thing cannot compete and meet their needs? ______________________________ Predation 12.Predation occurs when an animal ________ other animals for ________. Hunted organisms are called the ______. What are the ones doing the hunting called? ________________. The interactions of these two (predator and prey) can affect an ecosystem. If there are too many predators, the __________ population will _________. This may then increase _______________ for food among predators’ populations. If so, one or more will either _________ or ___________ to a new location. If there are not enough predators, the _________ population will ___________, creating competition for food among the __________ species. Therefore, one or more will either die out or move to a new ______________. Weather 13.Good weather will help ecosystems grow, but poor weather conditions can cause plant populations growth to __________ or _________. Natural ____________ also change ecosystems, like bad storms, ____________ and lightning. 14.Answer the Check and Reflect questions on page 60, #1 and 2