Biology 25th August

In Year 13 Biology class today we are given a task to rewrite a summary and include biological words that best describe this summary. A rabbit is active at dawn and dusk. It's normal activity is recorded in a lab for 6 days, then recorded in constant darkness for another 10 days. There is still a pattern to the rabbit's behaviour but it starts 20 minutes later each day. Describe / re-write what is happening using each of these words at least once: Zeitgeber entrained biological clock endogenous exogenous circadian circatidal phase shift period of nocturnal diurnal crepuscular biorhythm free-running A rabbit is active at dawn and dusk which has a biological word called crepuscular. The biorhythm for the rabbits is circadian not circatidal as the biorhythm only occurs near the beach involving the activity of tides. The zeitgeber is the rising and setting of the sun which is an exogenous cue. Rabbits are diurnal which means it is active during the day and sleeping during the night and is not nocturnal as that would mean rabbits are active during the night and sleeping during the day which isn't true. The rabbits normal activity is recorded in a lab over a period of 6 days including the zeitgeber which is entrained. Then they are recorded in constant darkness for another 10 days to analyse their activity. Now that the exogenous cue is eliminated their is no zeitgeber to reset the biological clock for rabbits therefore they have to rely on their endogenous cue. During the 10 days the rabbits were free-running which means there is no zeitgeber. There is still a pattern to the rabbit's behaviour but it starts 20 minutes later each day which means their is a phase shift.