Problem : To what does the German term Zeitgeber refer?A Zeitgeber is an environmental agent (such as light or temperature) that entrains an individual's behavior to that environment. Zeitgeber is German for "time-giver".
Problem : What is the difference between an endogenous stimulus and an exogenous stimulus?
An endogenous stimulus comes from within the body of an animal. An exogenous comes from the external environment of the animal.
What are behaviors that occur based on daily, monthly, and yearly cycles called?
Behaviors based on a daily cycle are called circadian. Month-based behaviors are called lunar and year-based behaviors are called circannual.
What stimuli can be used as Zeitgebers for circadian, lunar, and circannual behaviors?
Common circadian zeitgebers include sun and starlight. Lunar behaviors are often timed to tides. Circannual behaviors can be timed to seasonal temperature differences and the length of the day.