2.  Plants grow nearly everywhere on Earth but plants must adapt to their environment to survive.  In a tundra climate zone small plants and wildflowers grow  In an arid climate zone cacti can live for long periods without water.

3.  Geographers study where different plants grow by using vegetation zones  Each zone has a mix of plants that have adapted to the conditions of a particular area

5.  Tells us how crowded a place is.  To calculate population density: divide the total number of people living there by the location’s total land area  The higher the result, the more crowded Example: In 2000, New York City had a population density of more than 26,000 people per square mile. Bowling Green’s population density is 1,631 people per square mile

6.  Population density affects how people live.  Example: In Bowling Green most people use cars to get from place to place. In New York, people use subways, and ferries to get from place to place