If you watched the news on television last night, it's very likely that you saw a news story that talked about the environment. What do you think of when you hear the word environment? You probably think about efforts to protect wild animals, like tigers, or even about recycling aluminum cans, paper and plastics. What does the word environment mean? Why has it become such an important news topic?

The environment is the sum of all outside conditions that affect the life, development and survival of an organism.

In this first lesson we will look at the various roles that living organisms play and how they interact with their environment.  We'll also learn about how environmental  hazards effect these organisms.

By the end of this lesson you should be able to:

• Summarize the flow of energy from the sun through the various levels of the food chain
• Identify various elements of the carbon cycle, nitrogen cycle and water cycle
• Identify the relationship of dose and toxicity to the effects of exposure from environmental hazards and the relationship of exposure, toxicity and risk

Begin by clicking on the "Pre-Test" link to the left, then proceed with the rest of this unit by clicking on the "Lesson" link to the left.  When you get to the lesson guides, read each one.  When you are finished, return to this page to continue on to the activity and then to the post-test.