Why learn about the environment? The more obvious reason is that we, as human beings, depend on the environment for our survival. Endangering our environment thus risks endangering human beings, not to mention other creatures. Better understanding our environment can also deepen our appreciation for life, and improve economic efficiency and productivity since societies depend on their environments for economic resources. The following questions deal with pollution, waste and species extinction.    


1. Carbon monoxide contributes significantly to air pollution in the United States. Which of the following is the largest source of carbon monoxide?


2. What is the most common cause of pollution of streams, rivers, and oceans?


3. Where does most of the garbage in the United States end up?


4. What is the most common reason that animal species become extinct?


5. Scientists have not determined the best solution for disposing of nuclear waste. What is done with nuclear waste now in the United States?