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NZQA Plant and animal behaviour > Rhythms > Flashcards

Flashcards in Rhythms Deck (16)
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What are the two types of biological rhythms?

Exogenous (externally driven) and endogenous (internally driven)


What is the definition of an exogenous rhythm?

An exogenous rhythm is controlled by something outside the body "externally driven" eg. light availability.


What things may "drive" an exogenous rhythm?

Light availability, tide length, day length.


What is an endogenous rhythm?

Endogenous rhythms are controlled by internal biological clocks.


What is the difference between an exogenous rhythms and an endogenous rhythm?

Endogenous rhythms are internally driven and exogenous rhythms are externally driven.


What is a free-running period.

Where a biological rhythm is running during constant environmental conditions.


What drives an endogenous rhythm?

The internal clock.


Why so biological rhythms need to be "reset"?

The internal clock in humans is actually closer to 25 hours instead of 24 hours per day. So often endogenous rhythms in organisms are different lengths as the environment. Therefore the internal clock is reset, known as entrainment.


What are the purpose of zeitgebers?

Zeitgebers are the environmental cues that help reset an internal clock.


What are some common zeitgebers?

Light, temperature, humidity.


What does entrainment mean?

Reseting the internal/biological clock.


What does the term "phase shifting" mean?

Phase shifting is when the time of an activity or inactivity is pushed forwards or backwards. This occurs when an internal clock is entrained.


What is an actogram?

An actogram the the graphical display of the activity of an animal that has been isolated from environmental cues


What is the purpose of an actogram?

Using an actogram we are able to figure out whether a rhythm is endogenous or exogenous. They may also be used to determine the length of a biological rhythm.


What is shown on an actogram?

It shows when an organism is active and inactive over the course of usually a few selected days. It also shows any changes in the environment.


How do you determine the length of the biological rhythm using an actogram?

You look at the length of activity.