Which are true of a hypothesis?

A) It is the same thing as a theory.
B) It is assumed to be true and requires no further examination.
C) None of these.

Elevation variations in the land's surface might best be represented by an) :

A) topographic profile
B) geologic map
C) outcrop

In which river zone are plants that are adapted to attach to rocks mostly found? 

A)  in the source zone 
B)  in the transition zone 
C)  in the limnetic zone 
D)  in the floodplain zone

A(n)___________________________________ is used to show the effects of various dosages of a toxic substance on test organisms.

Which substance is non-destructive in the ozone layer? 

A)  CFCs 
B)  methyl bromide 
C)  halons 
D)  PCBs

Which part of a tropical rain forest receives the least amount of solar radiation? 

A)  the emergent layer 
B)  the canopy 
C)  the understory 
D)  the forest floor