Week 2 (Modules 3-4) Flashcards

1
Q

Proximate causality = ____ or ______ questions

A
  • how

- mechanism

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2
Q

Ultimate causality = _____ or ______ questions

A
  • why

- function

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3
Q

When did life arise on Earth?

A

~3.5 billion years ago

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4
Q

In which domains of life are circadian rhythms found?

A

all 3 (eukaryote, bacteria, archaea)

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5
Q

Circadian clocks have ______ several times

A

evolved

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6
Q

What is the ‘escape from light’ hypothesis?

A

Ancient organisms may have evolved to perform vulnerable cellular processes at night, so UV rays do not disrupt them

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7
Q

What are the two hypotheses for the origins of circadian rhythms?

A
  • escape from light/oxygen (external coordination)

- internal biochemical coordination

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8
Q

What is the ‘escape from oxygen’ hypothesis?

A

Ancient anaerobic organisms may have evolved circadian rhythms in order to produce antioxidants during the day, when photosynthesizing organisms produce oxygen

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9
Q

What is the ‘internal biochemical coordination’ hypothesis?

A

Organisms evolved circadian rhythms in order to be able to temporally separate internal processes that cannot occur at the same time

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10
Q

One of the most important functions of clocks is to anticipate _____

A

the change from day to night and back

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11
Q

Two uses of being able to predict the changes from night to day are:

A
  • organisms are able to predict when food will be readily available
  • organisms can predict when the best time to perform a biological function is
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12
Q

What is FAA?

A

Food-anticipatory activity - the emergence of activity prior to mealtime

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13
Q

At what time of day can rats and mice anticipate meals?

A

Any time of day

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14
Q

What are the two different modes of circadian clocks?

A
  • alarm clock mode

- wristwatch mode

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15
Q

What is time-place learning?

A

When animals can discriminate time of day by learning to go to a particular place at a particular time of day

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16
Q

What is time-compensated sun-compass orientation?

A

When animals use the location of the sun to navigate, also taking into account the movement of the sun throughout the day

17
Q

What is ‘swamping’?

A

When animals wait until a certain time using circadian clocks to perform an action that makes them vulnerable together

18
Q

What is temporal niche segregation?

A

When two competitor species in the same niche use a circadian clock to be active during different parts of the day

19
Q

What is photoperiodism?

A

When animals use circadian clocks to keep track of days passing, in order to anticipate yearly changes in the environment

20
Q

Disrupted circadian rhythms have been linked to higher mortality rates of ____

21
Q

Most organisms function optimally when _______

A

there is a match between the period of their circadian clock and the cycles of the environment

22
Q

Loss of circadian rhythms has been suggested to cause

A

reduced lifespan

23
Q

What is an oscillator?

A

Any device that produces a rhythm

24
Q

What is a pacemaker?

A

Controls other oscillators

25
What is an interval timer?
A clock that is limited to timing one interval, then must be reset
26
What two problems does entrainment solve?
- Adjusting the timing to fit with a 24-hour interval | - Synchronizing the rhythm with the environment
27
What is masking?
A direct effect of an environmental stimulus on behaviour
28
If synchrony to a changed LD cycle is instantaneous, this is probably due to ____
masking
29
What is the difference between positive and negative masking?
Negative masking suppresses a behaviour, while positive masking stimulates it
30
What is the non-parametric entrainment model?
The hypothesis that entrainment can occur with small daily phase adjustments (period of the rhythm is not a parameter)
31
What is a parameter?
A feature of a clock that can be set
32
What can you predict if you know the tau of a circadian clock and the shape of its phase response curve?
- limits to entrainment - phase of entrainment - gradual re-entrainment
33
What factors determine how long it takes to shift to a new time zone?
- the magnitude of the shift - the direction of travel - the timing of light exposure - parameters (wavelength, amplitude) of the light stimulus
34
What is the parametric entrainment model?
Hypothesizes that light entrains circadian rhythms by altering both the phase and period of the clock (period is a parameter of the rhythm)
35
Global environmental features are _______
- enduring - stable - nontrivial
36
From where did circadian clocks likely emerge?
primitive prokaryotic life forms
37
Where are local oscillators found?
In the specific body part they are responsible for providing a circadian rhythm for
38
What are three defining characteristics of circadian clocks?
- self-sustaining and have a ~24h period in consistent conditions - temperature compensated - entrainable by environmental stimuli