| A | B |
|---|
| natural resource | renewable or nonrenewable parts of the natural environment such as soil, crops, and water that are used by humans |
| renewable resource | resources replaced or recycled by natural processes; for example, oxygen is replenished during photosynthesis |
| nonrenewable resource | resource available in limited amounts that cannot be replaced and cannot be recycled quickly by natural means |
| fossil fuel | coal, oil, and natural gas formed from the buried remains of organisms |
| extinction | occurs when the last members of a species die; may be a natural process or the result of human activity such as hunting, urbanization, and the destruction of natural habitats |
| threatened species | species that have rapidly decreasing numbers of individuals; examples include African elephants and grizzly bears |
| endangered species | species with numbers of individuals so low that it is in danger of extinction; examples include manatees, the Florida panther, and loggerhead turtles |
| pollution | contamination of air, water, or land in such excess that they cannot be recycled by natural processes |
| particulate | solid particles of soot contained in smoke released by burning fossil fuels |
| smog | type of urban air pollution resulting from a combination of chemical pollutants, particulate matter, and sulfur dioxide |
| acid precipitation | rain or snow more acidic than unpolluted rainwater; leaches valuable nutrients from soil, causing tree death and plant tissue injury; damages some buildings and statues |
| ozone layer | protective layer of ozone at the top of the stratosphere; absorbs most of the sun's harmful radiation; chlorofluorocarbons (CFC's) have caused the ozone layer to thin |
| greenhouse effect | a natural phenomenon by which carbon dioxide and other atmospheric gases prevent heat from escaping into space; without the greenhouse effect, Earth would be too cold for life to exist |
| groundwater | fresh water from rain and surface streams that accumulates in underground reservoirs |
| biodegradable | solid wastes that can be broken down by natural processes; examples include wood products and food |
| nonbiodegradable | types of wastes that are not easily broken down and can exist in the environment for many years; examples include radioactive residues and plastics |
| preservation | keeping an organism or an area from harm or destruction by the establishment of parks, wildlife habitats, and other refuges |
| conservation | planned management of wildlife habitats and other natural areas to prevent exploitation or destruction |
