Chapter 2: Changing Populations
Completion requirements
Chapter 2: Changing Populations
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A large meteorite speeds toward Planet Earth. Upon impact with Earth, its deep impact throws so much dust up into the air that sunlight does not reach Earth’s plants for years. With sunlight blocked from the surface, mass extinctions occur, eliminating most of Earth’s species in a very short time. This event occurred at least once in Earth’s history. Nowadays, there are still many events that cause changes in the populations of living things but, from a global perspective, they are mostly on a small scale. An example of such a frequent population-changing event is a forest fire ravaging a natural landscape. |
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In this chapter you will study species survival and extinction within the natural environment over vast geological time spans. This study provides a basis for understanding the human impact on the present environment and for understanding global ecological issues.
- Turn to pages 468 and 469 of the textbook, and read the Chapter 2 introduction.
Have you ever lost something like, say, an MP3 player only to find it—after a long search—simply left on a chair? If the chair and MP3 player both have the same colour, the player can easily get lost. The outward appearance of things—including living things—affects the ease with which they can be found (or stay hidden). In the next activity you will study this phenomenon by using toothpicks. You might have fun trying it.
- Read the activity on page 469 of the textbook. Follow the directions, and answer the questions.
Note: As you race to pick up toothpicks, pick them up without trying to favour any colour. If you are working alone, have a friend or family member scatter the toothpicks and inform you when approximately a minute has passed.
Science 20 Textbook. Alberta Education