Good morning!! The purpose of both a dichotomous key and a field guide's purpose is to identify organisms. The only difference between the two is the a dichotomous key just uses descriptions to identify the animal with no pictures, but a field guide uses pictures to identify the organism. Another thing that separates the two is that the dichotomous key gives questions/descriptions that describe the organism, whereas the field guide uses a brief description of the animal. Hope I helped!!
Circadian rhythms ....its just behavior that is repeated over 24 hours
