Why do scientists study the rainforest?

There are traits like blood type and eye color, and others like speaking english or having a scar. what are the terms used to describe these different types of traits? how are each defined?

Which of the following items would serve as a primary source for a historian studiying the american civil war

In the context of c. h. cooley's theory of groups, identify each attribute as either belonging to a primary group or a secondary group.