Why does our heart beat faster when we exercise?

What are four key elements of the study of economics?

Which kingdom includes some organisms that have no nucleus and can live in an environment with an extremely high salt content

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.