Currently, legal and illegal immigration account for _____ of U.S. population growth.

Detritivores are consumers that release nutrients from the dead bodies of living organisms and return them to the soil, water, and air.

Of Earth’s remaining wilderness areas, about ____ are strictly or partially protected by law from human activities.

A chemical element cannot be broken down into simpler substances by chemical means.

Some United States cities are attempting to be more livable and more environmentally sustainable. Examples are:

In the United States, ____ of all urban transportation is by car.

The United States is the clear leader in total area of forests approved by the Forest Stewardship Council.

If you visited Curitiba, Brazil, you would expect to find

The world population increases by about ____ people each day.

Strip cutting of timber is a method of harvesting that