Drug is when the body has become accustomed to a medication after being on it for a length of time, and higher doses are required to achieve the desired effect.

Directions: read the descriptions of the four islands presented in the lesson. 1. list two new traits that each new species of rat might demonstrate as it adapts to the conditions on each island. 2. introduce one of the four new rat species to another island and describe one challenge it would encounter and one success as it adapts to its new environment.