Orientation in Time Flashcards
What are biological rhythms
they are rhythmic activities that occur at regular time periods within animals
they are linked to many environmental factors
describe what are circadian rhythms i.e what kind of rhythm are they what is the length of the rhythm what environmental cycle are they linked to and what factor are they triggered by
a type of daily rhythms
length of 24 hours
linked to the day and night cycle
triggered by light availability
what is an example of circadian rhythms
humans have circadian rhythms as we got to sleep at night and are awake during the day time.
other examples include nocturnal animals who stay awake during the night time and go to sleep during the day.
describe what are circANNUAL rhythms i.e what kind of rhythm are they what is the length of the rhythm what environmental cycle are they linked to and what factor are they triggered by
circannual are yearly rhythms
length of 365.25 days ( the amount of time it takes for the earth to orbit the sun)
linked to seasons
the seasons affect day length and so circannual rhythms are triggered by day length
what is an example of circannual rhythms
animals that experience migration and hibernation at certain times of the year which is linked to the seasons
an example of this is when bears hibernate during the winter
describe what are circTIDAL rhythms i.e what kind of rhythm are they what is the length of the rhythm what environmental cycle are they linked to and what factor are they triggered by
circatidal rhythms are related to tides
length of 12 hours
linked to tidal changes (which are controlled by the gravitational pull of the moon on the earth)
who has circatidal rhythms are how do tidal changes affect them
only animals living in tidal zones have circatidal rhythms are they will become active when the tide is high or in and inactive when the tide is low or out,
this is because when the tide is in the animals are submerged under water and this is the time for feeding and reproduction so they are active, where as when the tide is out, the organisms are exposed to air and threatened by drying out and therefore become inactive
what causes the changes in tides
the gravitational pull of the moon on the earth
the pull creates the tides
but the rise and the fall of tides are caused by earths rotation relative to the moon
describe what are circaLUNAR rhythms i.e what kind of rhythm are they what is the length of the rhythm what environmental cycle are they linked to and what factor are they triggered by
they are monthly rhythms
length of 29.5 days
that are related to the orbit of the moon around the earth
they are linked and triggered by the moon cycle
what is an example of circalunar rhythms
werewolves!!!! during a full moon werewolves turn from man to beast, this is a circalunar rhythm.
what are long day plants
they only flower during the long day lengths, and therefore only flower during summer
what are short day plants
they only flower during the short day lengths, and therefore only flower during winters
what are day neutral plants
these plants are not affected by the day length and flower during any day length and therefore any time of the year
what is phytochrome and how does it work
phytochrome is a type of plant pigment that comes in two forms, red and far red
phytochrome controls the photoperiodism repsonse, during the day there is lots of red light which is absorbed by the red pigment and converted to far red, then at night time the far red converts to red (and the cycle continues?)
how does phytochrome affect long day and short day plants
long day plants require a lot of far red pigment to flower and so therefore requires longer day lengths so that more red can convert into far red
short day plants require a lot of red pigment to flower and therefore requires shorter day lengths so that less red can convert to far red and there is more red for the plant to use to flower.
when do plants reproduce and why
plants try to flower at the same time each year so that their seeds will germinate at the same time and they do this when the chance of survival is the HIGHEST
for example if the flowers are pollinated by insects the flowering would need to occur when insects are most active.
what are exogenous rhythms
exogenous rhythms are rhythms that are externally driven, this means they are controlled by something outside of the body
what are controls and factors of exogenous rhythms
light availability
tide length
changing day length
what are endogenous rhythms
endogenous rhythms are internally driven meaning they are controlled by something within the body, (an internal clock), the internal clock regulates the rhythms of activities
what is the difference between endogenous rhythms and exogenous rhythms
endogenous rhythms are no affected by the environment and can continue even when the environment remains constant, where are exogenous rhythms are affected by the environment and when they it changes.
what are zeitgebers
environmental cues that reset the internal clock (light availability, temperature, humidity)
what is an example of zeitgebers
sunrise and sunset, a thing of the environment that tells our body when to wake up and start activity and when to go to bed and become inactive. this is controlled by light availability
what is entrainment
the act of resetting internal clock to match the environment
what is phase shifting
when an internal clock has been entrained, phase shifting occurs, it is when the time of activity or inactivity has been pushed backwards of forwards
what is an actogramy
actograms are graphs that show hen an organism is active or inactive over the course of one day, as well as the changes in an environment
what is an actogram
actograms are graphs that show hen an organism is active or inactive over the course of one day, as well as the changes in an environment
what are actograms used for
they are used to find out when a rhythm is exogenous or endogenous, the length of the rhythm and any phase shifting occurring
what is the purpose of photoperiodism
Photoperiodism is the regulation of seasonal activity by
day length.
